U.S. patent application number 14/392173 was filed with the patent office on 2016-07-07 for devices, systems and methods for monitoring knee replacements.
The applicant listed for this patent is William L. HUNTER. Invention is credited to William L. Hunter.
Application Number | 20160192878 14/392173 |
Document ID | / |
Family ID | 52142601 |
Filed Date | 2016-07-07 |
United States Patent
Application |
20160192878 |
Kind Code |
A1 |
Hunter; William L. |
July 7, 2016 |
DEVICES, SYSTEMS AND METHODS FOR MONITORING KNEE REPLACEMENTS
Abstract
Knee replacement prosthesis are provided, comprising a plurality
of sensors and at least one of a femoral component, a patellar
prosthesis and a tibial component.
Inventors: |
Hunter; William L.;
(US) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HUNTER; William L. |
Vancouver |
|
CA |
|
|
Family ID: |
52142601 |
Appl. No.: |
14/392173 |
Filed: |
June 23, 2014 |
PCT Filed: |
June 23, 2014 |
PCT NO: |
PCT/US2014/043736 |
371 Date: |
December 23, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61838317 |
Jun 23, 2013 |
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Current U.S.
Class: |
623/20.14 |
Current CPC
Class: |
A61B 5/0031 20130101;
A61F 2002/3067 20130101; A61F 2002/4668 20130101; A61B 5/4585
20130101; A61F 2/38 20130101; A61F 2/3877 20130101; A61F 2/389
20130101; A61B 5/01 20130101; A61F 2/3859 20130101; A61F 2002/4631
20130101; A61B 5/4851 20130101; A61F 2002/4674 20130101; A61F
2002/4666 20130101; A61B 5/686 20130101; A61B 2562/0219 20130101;
A61F 2002/488 20130101; A61B 5/11 20130101; A61B 5/4528 20130101;
A61B 5/112 20130101; A61F 2/4657 20130101 |
International
Class: |
A61B 5/00 20060101
A61B005/00; A61B 5/01 20060101 A61B005/01; A61F 2/38 20060101
A61F002/38; A61B 5/11 20060101 A61B005/11 |
Claims
1. A knee replacement prosthesis comprising: at least one of a
tibial component, a patellar prosthesis, and a femoral component;
and a plurality of sensors coupled to at least one of the tibial
component, patellar prosthesis, and femoral component.
2. The knee replacement prosthesis of claim 1 wherein the plurality
of sensors includes a sensor on the tibial component.
3. The knee replacement prosthesis of claim 1 wherein the plurality
of sensors includes a sensor on the patellar prosthesis.
4. The knee replacement prosthesis of claim 1 wherein the plurality
of sensors includes a sensor on the femoral component.
5. The knee replacement prosthesis according to any one of claims 1
to 4 wherein said sensor is selected from the group consisting of
accelerometers, pressure sensors, contact sensors, position
sensors, chemical microsensors, tissue metabolic sensors,
mechanical stress sensors and temperature sensors.
6. The knee replacement prosthesis according to claim 5 wherein
said accelerometer detects acceleration, tilt, vibration, shock and
or rotation.
7. The knee replacement prosthesis of claim 1 wherein the plurality
of sensors includes contact sensors positioned on the femoral
component.
8. The knee replacement prosthesis of claim 1 wherein the plurality
of sensors includes a plurality of contact sensors positioned on
the patellar component.
9. The knee replacement prosthesis of claim 1 wherein the plurality
of sensors includes a plurality of contact sensors positioned on
the tibial component.
10. A medical device, comprising a femoral component of a knee
replacement prosthesis and a plurality of sensors coupled to said
femoral component.
11. A medical device, comprising a patellar prosthesis of a knee
replacement prosthesis and a plurality of sensors coupled to said
patellar prosthesis.
12. A medical device, comprising a tibial component of a knee
replacement and a plurality of sensors coupled to said tibial
component.
13. The medical device according to any one of claims 10 to 12,
wherein said sensors appear within and/or on the surface of said
medical device.
14. The medical device according to any one of claims 10 to 13
wherein said sensor is selected from the group consisting of
accelerometers, pressure sensors, contact sensors, position
sensors, chemical microsensors, tissue metabolic sensors,
mechanical stress sensors and temperature sensors.
15. The medical device according to claim 14 wherein said
accelerometer detects acceleration, tilt, vibration, shock and or
rotation.
16. The knee replacement prosthesis according to any one of claims
1 to 9 or medical device according to any one of claims 10 to 15
further comprising: an electronic processor positioned upon and/or
inside at least one of the tibial component, patellar prosthesis
and/or the femoral component that is electrically coupled to
sensors.
17. The knee replacement prosthesis or medical device of claim 16
wherein the electric coupling is a wireless coupling.
18. The knee replacement prosthesis or medical device of claim 17
further including: a memory coupled to the electronic processor and
positioned upon and/or inside the at least one of tibial component,
patellar prosthesis and femoral component.
19. The knee replacement prosthesis or medical device according to
any one of claims 1 to 18 wherein said sensor is a plurality of
sensors which are positioned on or within said knee replacement at
a density of greater than 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 20
sensors per square centimeter.
20. The knee replacement or medical device according to any one of
claims 1 to 19 wherein said sensor is a plurality of sensors which
are positioned on or within said knee replacement at a density of
greater than 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 20 sensors per cubic
centimeter.
21. A method comprising: obtaining contact data from contact
sensors positioned at a plurality of locations between on and/or
within a knee replacement prosthesis or medical devices according
to any one of claims 1 to 20 of a patient; storing the data in a
memory device located on or within the knee replacement prosthesis
or medical device; and transferring the data from the memory to a
location outside the knee replacement prosthesis or medical
device.
22. The method according to claim 22 further including: obtaining
strain data from strain sensors positioned at a plurality of
locations on the knee replacement prosthesis or medical device of a
patient; storing the strain data in a memory located in said knee
replacement prosthesis or medical device; and transferring the
strain data from the memory to a memory in located outside the knee
replacement prosthesis or medical device.
23. The method according to claim 22 further including: obtaining
contact data from contact sensors positioned in a knee replacement
prosthesis or medical device according to any one of claims 1 to 19
of a patient; storing the contact data in a memory located in the
knee replacement prosthesis or medical device; and transferring the
data from the memory to a memory in a location outside of the knee
replacement prosthesis or medical device.
24. A method comprising: obtaining acceleration data from
accelerometers positioned at a plurality of locations on a knee
replacement prosthesis or medical device according to any one of
claims 1 to 19 located in-situ in the knee of a patient; storing
the acceleration data in a memory located in the knee replacement
prosthesis or medical device; and transferring the acceleration
data from the said memory in the knee replacement prosthesis or
medical device to a memory in a location outside the knee
replacement prosthesis or medical device.
25. A kit comprising the knee replacement prosthesis or medical
device according to any one of claims 1 to 19, further comprising
bone cement and/or bone screws comprising one or more sensors.
26. The kit according to claim 25 wherein said one or more sensors
are selected from the group consisting of accelerometers, pressure
sensors, contact sensors, position sensors, chemical microsensors,
tissue metabolic sensors, mechanical stress sensors and temperature
sensors.
27. The kit according to claim 25 or 26 wherein said sensors appear
on said prosthesis or medical device at a density of greater than
1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 20 sensors per square
centimeter.
28. The knee replacement, medical device, or kit according to any
one of claim 1-20 or 25-27 wherein the one or more of the sensors
are placed randomly within the knee replacement, medical device or
kit, and/or at specific locations within the knee replacement,
medical device or kit.
29. A method for detecting and/or recording an event in a subject
with a knee replacement or medical device as provided in any one of
claims 1 to 28, comprising the step of interrogating at a desired
point in time the activity of one or more sensors within the knee
replacement or medical device, and recording said activity.
30. The method according to claim 29 wherein the step of
interrogating is performed by a subject which has an implanted knee
replacement or medical device.
31. The method according to claim 30 wherein said recording is
performed on a wearable device.
32. The method according to any one of claims 29 to 31, wherein
said recording is provided to a health care provider.
33. A method for imaging a knee replacement, medical device or kit
according to any one of claims 1 to 20 or 25 to 27, comprising the
steps of (a) detecting the location of one or more sensors in a
knee replacement, medical device, or kit according to any one of
claims 1 to 20 or 25 to 27; and (b) visually displaying the
location of said one or more sensors, such that an image of the
knee replacement or medical device is created.
34. The method according to claim 33 wherein the step of detecting
occurs over time.
35. The method according to claim 34, wherein said visual display
shows changes in the positions of said sensors over time.
36. The method according to any one of claims 33 to 35 wherein said
visual display is a three-dimensional image of said knee
replacement or medical device.
37. A method for inserting a knee replacement, medical device or
kit according to any one of claims 1 to 20 or 25 to 27, comprising
the steps of (a) inserting a medical device according to any one of
claims 1 to 20 or 25 to 27 into a subject; and (b) imaging the
placement of said medical device according to the method of any one
of claims 33 to 36.
38. A method for examining a knee replacement, medical device or
kit according to any one of claims 1 to 20 or 25 to 27 which has
been previously inserted into a patient, comprising the step of
imaging the knee replacement or medical device according to the
method of any one of claims 33 to 36.
39. A method of monitoring a knee replacement, medical device, or
kit within a subject, comprising: transmitting a wireless
electrical signal from a location outside the body to a location
inside the subject's body; receiving the signal at a sensor
positioned on a knee replacement, medical device, or kit according
to any one of claims 1 to 20 or 25 to 27 located inside the body;
powering the sensor using the received signal; sensing data at the
sensor; and outputting the sensed data from the sensor to a
receiving unit located outside of the body.
40. The method according to claim 39 wherein said receiving unit is
a watch, wrist band, cell phone or glasses.
41. The method according to claim 39 or 40 wherein said receiving
unit is located within a subject's residence or office.
42. The method according to claims any one of claims 39 to 41
wherein said sensed data is provided to a health care provider.
43. The method according to any one of claims 39 to 42 wherein said
sensed data is posted to one or more websites.
44. A non-transitory computer-readable storage medium whose stored
contents configure a computing system to perform a method, the
method comprising: identifying a subject, the identified subject
having at least one wireless knee replacement, medical device, or
kit according to any one of claims 1 to 20 or 25 to 27, each
wireless knee replacement, medical device, or kit having one or
more wireless sensors; directing a wireless interrogation unit to
collect sensor data from at least one of the respective one or more
wireless sensors; and receiving the collected sensor data.
45. The non-transitory computer-readable storage medium of claim 44
whose stored contents configure a computing system to perform a
method, the method further comprising: identifying a plurality of
subjects, each identified subject having at least one wireless knee
replacement, medical device, or kit, each wireless knee
replacement, medical device, or kit having one or more wireless
sensors; directing a wireless interrogation unit associated with
each identified subject to collect sensor data from at least one of
the respective one or more wireless sensors; receiving the
collected sensor data; and aggregating the collected sensor
data.
46. The non-transitory computer-readable storage medium of claim 44
whose stored contents configure a computing system to perform a
method, the method further comprising: removing sensitive subject
data from the collected sensor data; and parsing the aggregated
data according to a type of sensor.
47. The non-transitory computer-readable storage medium of claim 44
whose stored contents configure a computing system to perform a
method, wherein directing the wireless interrogation unit includes
directing a control unit associated with the wireless interrogation
unit.
48. The non-transitory computer readable storage medium according
to any one of claims 44 to 47, wherein said knee replacement,
medical device, or kit is an assembly according to any one of
claims 1 to 20 or 25 to 27.
49. The storage medium according to any one of claims 44 to 48
wherein said collected sensor data is received on a watch, wrist
band, cell phone or glasses.
50. The storage medium according to any one of claims 44 to 49
wherein said collected sensor data is received within a subject's
residence or office.
51. The storage medium according to any one of claims 44 to 50
wherein said collected sensed data is provided to a health care
provider.
52. The storage medium according to any one of claims 44 to 51
wherein said sensed data is posted to one or more websites.
53. The method according to any one of claims 39 to 43, or storage
medium according to any one of claims 44 to 52, wherein said data
is analyzed.
54. The method or storage medium according to claim 53 wherein said
data is plotted to enable visualization of change over time.
55. The method or storage medium according to claim 53 or 54
wherein said data is plotted to provide a three-dimensional
image.
56. A method for determining degradation of a knee replacement,
medical device or kit, comprising the steps of a) providing to a
subject a knee replacement, medical device or kit according to any
one of claims 1 to 20 or 25 to 27, and b) detecting a change in a
sensor, and thus determining degradation of the knee replacement,
medical device or kit.
57. The method according to claim 56 wherein said sensor is capable
of detecting one or more physiological and/or locational
parameters.
58. The method according to claim 56 or 57 wherein said sensor
detects contact, fluid flow, pressure and/or temperature.
59. The method according to any one of claims 56 to 58 wherein said
sensor detects a location within the subject.
60. The method according to any one of claims 56 to 59 wherein said
sensor moves within the body upon degradation of the knee
replacement.
61. The method according to any one of claims 56 to 60 wherein the
step of detecting is a series of detections over time.
62. A method for determining an infection associated with a knee
replacement, medical device or kit comprising the steps of a)
providing to a subject a knee replacement, medical device or kit
according to any one of claims 1 to 20 or 25 to 27, wherein said
knee replacement, medical device or kit comprises at least one
temperature sensor and/or metabolic sensor, and b) detecting a
change in said temperature sensor and/or metabolic sensor, and thus
determining the presence of an infection.
63. The method according to claim 62 wherein the step of detecting
is a series of detections over time.
64. The method according to claim 62 or 63 wherein said change is
greater than a 1% change over the period of one hour.
65. The method according to claims 62 to 64 wherein said change is
a continually increasing temperature and/or metabolic activity over
the course of 4 hours.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit under 35 U.S.C.
.sctn.119(e) of U.S. Provisional Patent Application No. 61/838,317
filed Jun. 23, 2013, which application is incorporated herein by
reference in its entirety.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention relates generally to knee
replacements, and more specifically, to devices and methods for
monitoring the performance of total and partial knee
replacements
[0004] 2. Description of the Related Art
[0005] Knee replacement is one of the most common reconstructive
orthopedic surgical procedures. It may be carried out when the
patient loses sufficient use of the knee, typically as a result of
osteoarthritis, rheumatoid arthritis and other forms of arthritis
(lupus, psoriatic and others), a previous knee injury (knee
ligament tears (anterior cruciate, posterior cruciate, medial
collateral and/or lateral collateral ligaments) and meniscus tears)
and the sequellae of previous reconstructive surgery for the
treatment for these conditions, articular cartilage injuries, joint
dislocations, intra-articular fractures, and infections. Typically,
the surgery is indicated for the treatment of extreme or constant
joint pain, loss of range of motion, impaired ambulation and/or the
loss of function and impairment in the activities of normal daily
living; usually being indicated when there is evidence of
significant loss or degeneration of the articular cartilage of all
or parts of the knee.
[0006] The knee is generally divided into three "compartments",
medial (the joint surface on the inside of the knee), lateral (the
joint surface on outside of the knee), and patellofemoral (the
joint between the kneecap and the thighbone or femur). Knee
replacement can take a variety of different forms, depending on the
degree of injury and/or the extent of the disease. In total knee
replacement (TKR), both surfaces of the knee joint are replaced
(i.e., the femoral articular surface and the tibial articular
surface of the joint are replaced by a prosthesis); the patellar
(kneecap) surface may/or may not be replaced depending on the
degree of damage to the patella. In a partial or unicompartmental
knee replacement, only one or two of the medial, lateral or
patellofemoral portions of the joint are replaced (medial
compartment replacement is the most common).
[0007] The various components of a TKR typically include femoral
implant and a tibial implant (with or without replacing the surface
of the patella). The femoral component consists of a rounded
femoral condyle (often metal, but can be ceramic), the tibial
component consists of a flat metal shell (with or without a stem
that extends into the medullary canal of the tibia) that attaches
to the tibia with an inner polymeric (often polyethylene, but
ceramic and metal can be used) surface liner, and the patellar
component (if present) consists of a polymeric "button" cemented to
the posterior surface of the patella. Currently, the various
components of a TKR can be made from a variety of different
materials, including for example, polyethylene, ultrahigh molecular
weight polyethylene, ceramic, surgical-grade stainless steel,
cobalt chromium, titanium, and various ceramic materials. Within
certain devices, the femoral implant (typically made of a metal
such as stainless steel, titanium, or cobalt chromium) and the
metal portion of the tibial component (typically also made of a
metal such as stainless steel, titanium, or cobalt chromium) can be
designed with a surface coating to encourage incorporation of the
implant within the bone of the femur and the tibia. The prosthesis
may or may not be held in place with the use of bone cement
(PMMA--polymethylmethacrylate). Representative examples of the
various components of a knee replacement are described in U.S. Pat.
Nos. 5,413,604, 5,906,643, 6,019,794 and 7,922,771.
[0008] FIG. 1 shows a total knee joint of a type known in the art,
as well as a unicompartmental (medial compartment) knee
replacement. FIG. 2 illustrates the components and materials of a
typical artificial joint (10), including a metallic tibial plate
(5) and tibial stem (2) (present in this Figure, although some
tibial plate components do not have stems), a polyethylene
articulating surface (7), cement used to hold the various
components in place (4), patellar "button" prosthesis (8), and the
femoral knee component 9. FIG. 3 depicts another typical TKR, with
a femoral component, a tibial plate and a patellar button which may
be attached with screws and/or cement to the underlying bone (as
opposed to a stemmed tibial plate).
[0009] Unfortunately, when a total knee is inserted, various
complications may arise intra-operatively, in the post-operative
period and over time. For example, intra-operatively, the surgeon
may wish to confirm correct anatomical alignment of the prosthesis
and/or any motion between the prosthesis and the surrounding bone
so that adjustments can be made during the procedure.
Post-operatively, the patient may experience inflammation and pain
if there is slight movement, partial (subluxation) or full
dislocation of any of the components of the knee prosthesis. Longer
term, there may be progressive wear between the femoral surface and
the tibial surface, which leads to improper operation of the knee
joint. Depending on the types of materials used for the tibial
surface and the femoral surface, prolonged wear can result in the
generation of small debris particles which lead to inflammation and
bone erosion surrounding the implant. A related common complication
occurs when, over a period of time (for example 8-12 years), bone
loss occurs in the tissues surrounding the implant (due to a
process known as osteolysis) that leads to loosening and ultimately
failure of the prosthesis. All of the above acute and chronic
complications may degrade the performance of the knee, result in
difficulty in movement and ambulation, and may cause pain and
inflammation for the patient.
[0010] As mentioned, one of the most common and serious
complications of TKR is erosion of the bone around the implant
(osteolysis) which may be caused by material debris (metal,
ceramic, and/or polyurethane fragments) generated by friction, and
causing inflammation and bone loss. Other potential causes of
inflammation and osteolysis are implant vibration and motion,
improper patient usage/activities, improper alignment (including
improper tracking of the patella), subclinical dislocation
(subluxation) of the tibial-femoral joint and the patellar-femoral
joint, mechanical wear and tear, material failure or breakage,
loosening of the bond between the bone and the cement, lack of
biocompatibility between the implant materials and the surrounding
bone, metal allergy, and lack of biocompatibility between the bone
cement and the surrounding bone. The ability to detect these
changes early and institute corrective or preventative measures
would be of great utility in the management of TKR patients.
Additional complications that could benefit from early detection
and intervention include infection, bone fracture, implant
microfracture, nerve impingement, deep vein thrombosis, loss of
motion, and instability.
[0011] Currently, post-operative, in-hospital monitoring of knee
replacement surgery patients is conducted through personal visits
by the hospital staff and medical team, physical examination of the
patient, medical monitoring (vital signs, etc.), evaluation of knee
range of motion (ROM), physiotherapy (including early mobilization
and activity), and diagnostic imaging studies and blood work as
required. Once the patient is discharged from hospital, prosthesis
performance and patient satisfaction is checked during periodic
doctor's office visits where a thorough history, physical exam and
supplemental imaging and diagnostic studies are used to monitor
patient progress and identify the development of any potential
complications. During such visits, the surgeon typically evaluates
the range of motion of the knee, attempts to identify any pain that
occurs during certain motions or actions, and questions the patient
to determine activity levels, daily functioning, pain control, and
rehabilitation progress.
[0012] Unfortunately, most of the patient's recuperative period
occurs between hospital and/or office visits. It can, therefore, be
very difficult to accurately measure and follow full joint range of
motion (ROM can change depending on pain control, degree of
anti-inflammatory medication, time of day, recent activities,
and/or how the patient is feeling at the time of the examination),
"real life" prosthesis performance, patient activity levels,
exercise tolerance, and the effectiveness of rehabilitation efforts
(physiotherapy, medications, etc.) from the day of surgery through
to full recovery. For much of this information, the physician is
dependent upon patient self-reporting or third party observation to
obtain insight into post-operative treatment effectiveness and
recovery and rehabilitation progress; in many cases this is further
complicated by a patient who is uncertain what to look for, has no
knowledge of what "normal/expected" post-operative recovery should
be, is non-compliant, or is unable to effectively communicate their
symptoms. Furthermore, identifying and tracking complications (in
and out of hospital) prior to them becoming symptomatic, arising
between doctor visits, or those whose presence is difficult for the
patient (and/or the physician) to detect would also provide
beneficial, additional information to the management of TKR and
partial knee replacement patients. Currently, in all instances,
neither the physician nor the patient has access to the type of
"real time," continuous, objective, prosthesis performance
measurements that they might otherwise like to have.
[0013] The present invention discloses novel total and partial knee
replacements which overcome many of the difficulties of previous
knee prostheses, methods for constructing and monitoring these
novel knee replacements, and further provides other related
advantages.
SUMMARY
[0014] Briefly stated, full and partial knee prostheses are
provided with a number of sensors to monitor the integrity and
efficaciousness of the artificial knee joint within the patient.
The sensors may be positioned on the outer surface of the
prosthetic knee, on the inner surfaces of the prosthetic knee,
within the prosthetic material (stainless steel, titanium, cobalt
chromium, polyurethane, high molecular weight polyurethane,
ceramics, etc.) itself, between the various components that
comprise the prosthetic knee, the screws and/or fastening hardware
(if present) used to secure the prosthesis in place, within the
bone cement (e.g., PMMA, or PMMA and MMA copolymer blends) used to
secure the knee (if present), and/or within the tissues surrounding
the prosthesis. Within certain embodiments, the sensors are of the
type that are passive and thus do not require their own power
supply.
[0015] Within one aspect of the invention, assemblies are provided
for positioning and placement within a patient an implant
comprising a total or partial knee prosthesis; and one or more
sensors positioned on, in, or around the prosthesis, and/or within
the bone cement and/or bone screws or anchors utilized to attach
the prosthesis. Within other aspects of the invention, medical
devices are provided comprising at least one of: a tibial
component, patellar prosthesis, or femoral component, and one or
more sensors. For purpose of clarity, the one or more sensors may
be purposely placed at specific locations on the knee replacement
prosthesis, medical device, and/or bone screw or anchor, and/or
randomly dispersed across, upon and within the knee replacement
prosthesis, medical device, bone screw or anchor, and bone cement.
Hence, use of the terms or phrases "are placed", "appear" or
"utilized" should not be deemed to require specific placement,
unless a specific placement is required.
[0016] Within various embodiments the sensor can be positioned on
an outer surface of the prosthetic knee, on an inner surface of the
prosthetic knee, within the materials used to construct the
prosthetic knee, between the various components that make up the
prosthetic knee, the screws and/or fastening hardware (if present)
used to secure the prosthesis in place, on or in the bone cement
used to secure the prosthetic knee, on or in the tissues
surrounding the prosthetic knee (typically bone or bone marrow, but
also muscle, ligament, tendon, joint capsule and/or synovial
compartment), or any combination of these. Representative examples
of sensors suitable for use within the present invention include
accelerometers (acceleration, tilt, vibration, shock and rotation
sensors), pressure sensors, contact sensors, position sensors,
chemical microsensors, tissue metabolic sensors, mechanical stress
sensors and temperature sensors. Within particularly preferred
embodiments the sensor is a wireless sensor, or a sensor connected
to a wireless microprocessor.
[0017] Within further embodiments a plurality of the aforementioned
sensors are positioned on, within, or around (bone cement, bone
screws or tissue) the prosthetic knee, and within preferred
embodiments, the prosthetic knee can contain more than one type of
sensor (e.g., one or more of, or any combination of the following:
acceleration sensors, tilt sensors, vibration sensors, shock
sensors, rotation sensors, pressure sensors, contact sensors,
position sensors, chemical microsensors, tissue metabolic sensors,
and mechanical stress sensors).
[0018] According to various embodiments, sensors are placed at
different locations in a replacement knee joint in order to monitor
the operation, movement, medical imaging (both prosthesis and
surrounding tissues), function, wear, performance, potential side
effects, medical status of the patient and the medical status of
the artificial knee and its interface with the live tissue of the
patient. Live, continuous, in situ, monitoring of patient activity,
patient function, prosthesis activity, prosthesis function,
prosthesis performance, prosthesis and joint alignment, patellar
tracking, prosthesis and joint forces and mechanical stresses,
prosthesis and surrounding tissue anatomy (imaging), mechanical and
physical integrity of the prosthesis, patellar tracking and
potential side effects is provided. In addition, information is
available on many aspects of the knee replacement prosthesis and
its interaction with the patient's own body tissues, including
clinically important measurements not currently available through
physical examination, medical imaging and diagnostic medical
studies.
[0019] According to one embodiment, the sensors provide evaluation
data on the range of motion (ROM) of the knee. Currently, ROM is
usually measured clinically by the physician passively moving the
knee joint through a full range of motion during physical
examination and recording the results (degrees of flexion,
extension, anterior/posterior stability and medial/lateral
stability; see, e.g., FIG. 4). Motion sensors and accelerometers
can be used to accurately determine the full ROM of the prosthetic
knee joint both during physical examination and during normal daily
activities between visits. Similarly, motion sensors and
accelerometers can be used to accurately measure any
anterior/posterior or medial/lateral instability (including full,
partial or subclinical dislocation) of the prosthetic knee joint
both during physical examination and during normal daily activities
between visits. Additionally, motion sensors and accelerometers can
be used to accurately measure any improper tracking of the patella
and/or patellar instability (including full, partial or subclinical
subluxation) during physical examination and during normal daily
activities between visits.
[0020] According to one embodiment, contact sensors are provided
between the prosthesis and the surrounding bone, between the screws
and/or fastening hardware (if present) and the surrounding bone,
between the prosthesis and the surrounding bone cement (if
present), and/or between the bone cement (if present) and the
surrounding bone in order to measure bone erosion and loosening
around the implant. In other embodiments, vibration sensors are
provided to detect the vibration between the prosthesis and the
surrounding bone, between the screws and/or fastening hardware (if
present) and the surrounding bone, between the prosthesis and the
surrounding bone cement, between the bone cement and the
surrounding bone as an early indicator of motion and loosening. In
other embodiments, strain gauges are provided to detect the strain
between the prosthesis and the surrounding bone, between the screws
and/or fastening hardware (if present) and the surrounding bone,
between the prosthesis and the surrounding bone cement, between the
bone cement and the surrounding bone, and also the strain which is
exerted on the various portions of the prosthesis. Sudden increases
in strain may indicate that too much stress is being placed on the
replacement prosthesis, which may increase damage to the body. For
example, a gradual, long-term decrease in strain may cause bone
reabsorption around the implant, leading to loosening of the
prosthesis or fractures in the bone surrounding the prosthesis,
while a gradual, long-term increase in strain may lead to
microfractures of the prosthesis materials themselves.
[0021] According to other embodiments, accelerometers are provided
which detect vibration, shock, tilt and rotation. According to
other embodiments, sensors for measuring surface wear, such as
contact or pressure sensors, may be embedded at different depths
within the femoral articular surface, the tibial articular surface,
and/or the patellar articular surface in order to monitor articular
surface erosion. In other embodiments, position sensors, as well as
other types of sensors, are provided which indicate the range of
motion and monitor for partial (or complete) femoral-tibial knee
dislocation or subluxation in actual use over a period of time,
improper tracking of the patella and/or subluxation of the
patellar-femoral joint, or movement between the interconnected
components of the prosthesis (and the anchoring hardware)
itself.
[0022] Within further embodiments, the artificial knee (total or
partial) can contain sensors at specified densities in specific
locations. For example, the artificial knee can have a density of
sensors of greater than one, two, three, four, five, six, seven,
eight, nine, or ten sensors (e.g., acceleration sensors, tilt
sensors, vibration sensors, shock sensors, rotation sensors,
pressure sensors, contact sensors, position sensors, chemical
microsensors, tissue metabolic sensors, and mechanical stress
sensors, or any combination of these) per square centimeter of the
device. Within other embodiments, the artificial knee (total or
partial) can have a density of sensors of greater than one, two,
three, four, five, six, seven, eight, nine, or ten sensors (e.g.,
acceleration sensors, tilt sensors, vibration sensors, shock
sensors, rotation sensors, pressure sensors, contact sensors,
position sensors, chemical microsensors, tissue metabolic sensors,
and mechanical stress sensors, or any combination of these) per
cubic centimeter of the device. Within related embodiments, the
sensors (e.g., acceleration sensors, tilt sensors, vibration
sensors, shock sensors, rotation sensors, pressure sensors, contact
sensors, position sensors, chemical microsensors, tissue metabolic
sensors, and mechanical stress sensors) can be positioned at
particular locations on, within, or around the artificial knee,
including for example, the femoral component (medial, lateral or
both), the tibial plate, the tibial stem (if present), the tibial
lining, the prosthetic patellar lining, within portions of the
device which are to be connected (e.g., the connecting segments of
the tibial cup and the tibial lining), the screws and/or fastening
hardware (if present) used to secure the prosthesis in place, and
around the artificial knee (on or in the bone cement used to secure
the prosthetic knee, on or in the tissues surrounding the
prosthetic knee--typically bone or bone marrow, but also muscle,
ligament, tendon, joint capsule and/or synovial compartment).
[0023] Within certain embodiments of the invention, the total or
partial knee prosthesis is provided with a specific unique
identifying number, and within further embodiments, each of the
sensors on, in or around the prosthetic knee each have either a
specific unique identification number, or a group identification
number (e.g., an identification number that identifies the sensor
as an acceleration sensor, a tilt sensor, a vibration sensor, a
shock sensor, a rotation sensor, a pressure sensor, a contact
sensor, a position sensor, a chemical microsensor, a tissue
metabolic sensor, or a mechanical stress sensor). Within yet
further embodiments, the specific unique identification number or
group identification number is specifically associated with a
position on, in or around the prosthetic knee.
[0024] Within other aspects of the invention methods are provided
for monitoring an implanted total or partial knee prosthesis
comprising the steps of transmitting a wireless electrical signal
from a location outside the body to a location inside the body;
receiving the signal at a sensor positioned on, in or around an
artificial knee located inside the body; powering the sensor using
the received signal; sensing data at the sensor; and outputting the
sensed data from the sensor to a receiving unit located outside of
the body.
[0025] Within other aspects of the invention methods are provided
for imaging a knee replacement or medical device as provided
herein, comprising the steps of (a) detecting the location of one
or more sensors in a knee replacement or medical device; and (b)
visually displaying the location of said one or more sensors, such
that an image of the knee replacement or medical device is created.
Within various embodiments, the step of detecting may be done over
time, and the visual display may thus show positional movement over
time. Within certain embodiments the image which is displayed is a
two or three-dimensional image. Within preferred embodiments the
various images may be collected and displayed in a time-sequence
(e.g., as a moving image or `movie-like` image).
[0026] The imaging techniques provided herein may be utilized for a
wide variety of purposes. For example, within one aspect, the
imaging techniques may be utilized during a surgical procedure in
order to ensure proper placement and working of the knee
replacement or medical device. Within other embodiment, the imaging
techniques may be utilized post-operatively in order to examine the
knee replacement or medical device, and/or to compare operation
and/or movement of the device over time.
[0027] The integrity of the partial or total knee prosthesis can be
wirelessly interrogated and the results reported on a regular
basis. This permits the health of the patient to be checked on a
regular basis or at any time as desired by the patient and/or
physician. Furthermore, the prosthesis can be wirelessly
interrogated when signaled by the patient to do so (via an external
signaling/triggering device) as part of "event recording"--i.e.
when the patient experiences a particular event (e.g. pain, injury,
instability, etc.) she/he signals/triggers the device to obtain a
simultaneous reading in order to allow the comparison of
subjective/symptomatic data to objective/sensor data. Matching
event recording data with sensor data can be used as part of an
effort to better understand the underlying cause or specific
triggers of a patient's particular symptoms. Hence, within various
embodiments of the invention methods are provided for detecting
and/or recording an event in a subject with one of the total or
partial knee replacements provided herein, comprising the
interrogating at a desired point in time Hence, within one aspect
of the invention methods are provided for detecting and/or
recording an event in a subject with a knee replacement or medical
device as provided herein, comprising the step of interrogating at
a desired point in time the activity of one or more sensors within
the knee replacement or medical device, and recording said
activity. Within various embodiments, they may be accomplished by
the subject and/or by a health care professional. Within related
embodiments, the step of recording may be performed with one or
more wired devices, or, wireless devices that can be carried, or
worn (e.g., a cellphone, watch, wristband, and/or glasses). Within
further embodiments, the worn devices (e.g. cellphone, watch,
wristband and/or glasses may have sufficient processing power and
memory to be able to carry out further data collection and
analysis.
[0028] Within further embodiments, each of the sensors contains a
signal-receiving circuit and a signal output circuit. The
signal-receiving circuit receives an interrogation signal that
includes both power and data collection request components. Using
the power from the interrogation signal, the sensor powers up the
parts of the circuitry needed to conduct the sensing, carries out
the sensing, and then outputs the data to the interrogation module.
The interrogation module acts under control of a control unit which
contains the appropriate I/O circuitry, memory, a controller in the
form of a microprocessor, and other circuitry in order to drive the
interrogation module. Within yet other embodiments the sensor
(e.g., an acceleration sensor, a tilt sensor, a vibration sensor, a
shock sensor, a rotation sensor, a pressure sensor, a contact
sensor, a position sensor, a chemical microsensor, a tissue
metabolic sensor, or a mechanical stress sensor) are constructed
such that they may readily be incorporated into or otherwise
mechanically attached to the knee prosthesis (e.g., by way of a an
opening or other appendage that provides permanent attachment of
the sensor to the knee prosthesis) and/or readily incorporated into
the bone cement or the tissues that surround the knee
prosthesis.
[0029] Within yet other aspects of the invention methods devices
are provided suitable for transmitting a wireless electrical signal
from a location outside the body to a location inside the body;
receiving the signal at one of the aforementioned sensors
positioned on, in or around a prosthetic knee located inside the
body; powering the sensor using the received signal; sensing data
at the sensor; and outputting the sensed data from the sensor to a
receiving unit located outside of the body. Within certain
embodiments the receiving unit can provide an analysis of the
signal provided by the sensor.
[0030] The data collected by the sensors can be stored in a memory
located within the femoral component, the tibial plate and/or the
tibial stem. During a visit to the physician, the data can be
downloaded via a wireless sensor, and the doctor is able to obtain
data representative of real-time performance of the prosthesis.
[0031] The advantages obtained include more accurate monitoring of
the prosthesis and permitting medical reporting of accurate, in
situ, data that will contribute to the health of the patient. The
details of one or more embodiments are set forth in the description
below. Other features, objects and advantages will be apparent from
the description, the drawings, and the claims. In addition, the
disclosures of all patents and patent applications referenced
herein are incorporated by reference in their entirety.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is an illustration of a total knee replacement, and a
unicompartmental knee replacement.
[0033] FIG. 2 is an exploded view which illustrates various
components of a total knee replacement.
[0034] FIG. 3 illustrates the components of another total knee
replacement.
[0035] FIG. 4 illustrates a representative range of motion (ROM)
for a subject with a total knee replacement.
[0036] FIG. 5 illustrates a TKR with various contact sensors.
[0037] FIG. 6 illustrates a TKR with various strain gauges.
[0038] FIG. 7 illustrates a TKR with various accelerometers.
[0039] FIG. 8 illustrates a TKR with various positional
sensors.
[0040] FIG. 9 illustrates a TKR with sensors placed to detect
articular wear.
[0041] FIG. 10 illustrates an information and communication
technology system embodiment arranged to process sensor data.
[0042] FIG. 11 is a block diagram of a sensor, interrogation
module, and a control unit according to one embodiment of the
invention.
[0043] FIG. 12 is a schematic illustration of one or more sensors
positioned on a knee replacement within a subject which is being
probed for data and outputting data, according to one embodiment of
the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0044] Briefly stated the present invention provides a variety of
knee replacements that can be utilized to monitor the integrity and
efficaciousness of the device. Prior to setting forth the invention
however, it may be helpful to an understanding thereof to first set
forth definitions of certain terms that are used hereinafter.
[0045] "Knee replacement" or "knee prosthesis" as that term is
utilized herein, may take a variety of different forms and may
involve replacement of all (total knee replacement) or portions
(partial knee replacement) of the patient's knee joint with
synthetic materials. In total knee replacement (TKR), both the
femoral side and the tibial side are replaced. In a partial or
unicompartmental knee replacement, only one or two portions
(surfaces--tibial or femoral; or compartments--medial, lateral or
patellar) of the knee are replaced.
[0046] The various components of a TKR can typically include a
femoral implant, a patellar implant, and a tibial implant (which
can be composed of a tibial plate--with or without a stem--and a
tibial liner). Currently, the various components can be made from a
variety of different materials, including for example,
polyethylene, ultrahigh molecular weight polyethylene, ceramic,
surgical-grade stainless steel, cobalt chromium, titanium, and
various ceramic materials. Within certain devices, the femoral
implant (typically made of a metal such as stainless steel,
titanium, or cobalt chromium) can be designed with a bone surface
coating to encourage incorporation of the implant within the femur
and the tibial plate (and stem) can also have a surface coating to
encourage incorporation into the tibia. Representative examples of
the various components of a knee replacement are described in U.S.
Pat. Nos. 5,413,604, 5,906,643, 6,019,794 and 7,922,771.
[0047] "Bone Cement" refers to a material that can be administered
between the prosthetic hardware and the surrounding bone and
hardens in place when cooled (or otherwise activated); it is an
agent used to secure one or more of the components (the prosthetic
femur surface, the tibial plate/stem, the patellar "button") of the
prosthesis to the appropriate bony tissue (femur, tibia, tibial
medulla, patella). Bone cement is often composed of PMMA
(polymethylmethacrylate) or PMMA and MMA copolymer blends. It
should be noted that bone screws and/or other metallic (or
polymeric) securing devices can also be used to assist in anchoring
the prosthetic components to the surrounding bony tissues.
[0048] The present invention provides knee prosthesis (which may
include a full or a partial implant), medical devices (e.g., a
portion of a knee implant, and/or components or materials which are
useful in the process of implanting the device), and kits (e.g., a
knee prosthesis, medical device, and additional necessary materials
such as bone cement and any associated delivery devices), all of
which have sensors as described in further detail below. The knee
prosthesis, medical devices and kits as provided herein (including
related materials such as bone cement) are preferably sterile,
non-pyrogenic, and/or suitable for use and/or implantation into
humans. However, within certain embodiments of the invention the
knee prostheses, medical devices and/or kits can be made in a
non-sterilized environment (or even customized to an individual
subject), and sterilized at a later point in time.
[0049] "Sensor" refers to a device that can be utilized to measure
one or more different aspects of a body, of a knee prosthesis,
medical device or kit inserted within a body, and/or the integrity,
impact, efficaciousness or effect of the knee prosthesis, medical
device or kit inserted within a body. Representative examples of
sensors suitable for use within the present invention include, for
example, fluid pressure sensors, contact sensors, position sensors,
pulse pressure sensors, liquid (e.g., blood) volume sensors, liquid
(e.g., blood) flow sensors, chemistry sensors (e.g., for blood
and/or other fluids), metabolic sensors (e.g., for blood and/or
other fluids), accelerometers, mechanical stress sensors and
temperature sensors. Within certain embodiments the sensor can be a
wireless sensor, or, within other embodiments, a sensor connected
to a wireless microprocessor. Within further embodiments one or
more (including all) of the sensors can have a Unique Sensor
Identification number ("USI") which specifically identifies the
sensor.
[0050] A wide variety of sensors (also referred to as
Microelectromechanical Systems or "MEMS", or Nanoelectromechanical
Systems or "NEMS", and BioMEMS or BioNEMS, see generally
https://en.wikipedia.org/wiki/MEMS) can be utilized within the
present invention. Representative patents and patent applications
include U.S. Pat. Nos. 7,383,071 and 8,634,928, and U.S.
Publication Nos. 2010/0285082, and 2013/0215979. Representative
publications include "Introduction to BioMEMS" by Albert Foch, CRC
Press, 2013; "From MEMS to Bio-MEMS and Bio-NEMS: Manufacturing
Techniques and Applications by Marc J. Madou, CRC Press 2011;
"Bio-MEMS: Science and Engineering Perspectives, by Simona
Badilescu, CRC Press 2011; "Fundamentals of BioMEMS and Medical
Microdevices" by Steven S. Saliterman, SPIE--The International
Society of Optical Engineering, 2006; "Bio-MEMS: Technologies and
Applications", edited by Wanjun Wang and Steven A. Soper, CRC
Press, 2012; and "Inertial MEMS: Principles and Practice" by Volker
Kempe, Cambridge University Press, 2011; Polla, D. L., et al.,
"Microdevices in Medicine," Ann. Rev. Biomed. Eng. 2000,
02:551-576; Yun, K. S., et al., "A Surface-Tension Driven Micropump
for Low-voltage and Low-Power Operations," J.
Microelectromechanical Sys., 11:5, October 2002, 454-461; Yeh, R.,
et al., "Single Mask, Large Force, and Large Displacement
Electrostatic Linear Inchworm Motors," J. Microelectromechanical
Sys., 11:4, August 2002, 330-336; and Loh, N. C., et al., "Sub-10
cm.sup.3 Interferometric Accelerometer with Nano-g Resolution," J.
Microelectromechanical Sys., 11:3, June 2002, 182-187; all of the
above of which are incorporated by reference in their entirety.
[0051] Within various embodiments of the invention the sensors
described herein may be placed at a variety of locations and in a
variety of configurations, including on the inside, within, and/or
outer surface (or surfaces) of the knee prosthesis, medical device
or kit, as well as between the knee prosthesis, medical device or
kit and any device it might carry (e.g., a delivery or installation
device). As will be readily evident given the disclosure provided
herein, the sensors may be placed at multiple locations (i.e.,
inside, within and on the outer surface) of the knee prosthesis,
medical device or kit at the same time. Within certain embodiments
the knee prosthesis, medical device or kit, associated medical
device (e.g., delivery instrument) or kit comprises sensors at a
density of greater than 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or greater
than 10 sensors per square centimeter. Within other aspects the
knee prosthesis, medical device or kit, associated medical device
(e.g., delivery instrument) or kit comprises sensors at a density
of greater than 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or greater than 10
sensors per cubic centimeter. Within either of these embodiments
there can be less than 50, 75, 100, or 100 sensors per square
centimeter, or per cubic centimeter. Within various embodiments the
at least one or more of the sensors may be placed randomly, or at
one or more specific locations within the catheter, medical device,
or kit as described herein.
[0052] In various embodiments, the sensors may be placed within
specific locations and/or randomly throughout the knee prosthesis,
medical device or kit, associated medical device (e.g., delivery
instrument) or kit. In addition, the sensors may be placed in
specific patterns (e.g., they may be arranged in the pattern of an
X, as oval or concentric rings around the knee prosthesis, medical
device or kit, associated medical device (e.g., delivery
instrument) or kit.
Representative Embodiments of Knee Prosthesis, Medical Devices and
Kits
[0053] In order to further understand the various aspects of the
invention provided herein, the following sections are provided
below: A. Knee Prosthesis, Medical Devices and Kits and their Use;
B. Use of Knee Prosthesis, Medical Devices and Kits to Deliver
Therapeutic Agent(s); C. Use of a Knee Prosthesis, Medical Device
or Kit having Sensors to Measure Degradation or Wearing of an
Implant; D. Methods for Monitoring Infection in Knee Prosthesis,
Medical Devices and Kits; E. Further Uses of Sensor-containing Knee
Prosthesis, Medical Devices and Kits in Healthcare; F. Generation
of Power from Knee Prosthesis, Medical Devices and Kits; G. Medical
Imaging and Self-Diagnosis of Assemblies Comprising Knee
Prosthesis, Medical Devices and Kits, Predictive Analysis and
Predictive Maintenance; H. Methods of Monitoring Assemblies
Comprising Knee Prosthesis, Medical Devices and Kits; and I.
Collection, Transmission, Analysis, and Distribution of Data from
Assemblies Comprising Knee Prosthesis, Medical Devices and
Kits.
A. Knee Prosthesis, Medical Devices and Kits and their Use
[0054] Knee replacement is carried out when the patient loses
sufficient use of the knee so as to result in disability, loss of
movement and function, impaired ambulation, and/or continuous joint
pain and discomfort. Common causes of impaired knee function
leading to total or partial knee replacement include various types
of arthritis (such as rheumatoid arthritis or osteoarthritis, and
trauma (for example, previous knee ligament injuries or
cartilage/meniscus tears). In most patients, the operation is
successful in improving ambulation, restoring normal daily function
and reducing pain; as a result, it is a very common orthopedic
procedure in the Western World.
[0055] FIGS. 5, 6, 7, 8 and 9 illustrate several prosthesis 10 in
the form of a total knee replacement having one or more sensors
positioned in or on the prosthesis in order to monitor, in situ,
the real-time operation of the prosthesis, levels of patient
function and activity, and the prosthesis performance acutely and
over time. A variety of these sensors will now be described
according to various embodiments.
[0056] In one embodiment shown in FIG. 5, one or more contact
sensors 22 are provided throughout the implant, including contact
sensors 22A distributed on and within the femoral condyle
prosthesis-bone interface, contact sensors 22B distributed on and
within the tibial bone--metal plate (and stem if present)
interface, and contact sensors 22C distributed on within the
patellar prosthesis (patellar "button")--patellar bone interface.
In some embodiments, the contact sensors are on the prosthetic
components themselves (tibial, femur and patellar segments), while
in others the contact sensors are contained on/within the bone
cement (if present) used to secure the prosthesis to the
surrounding bone, and in still other embodiments the contact
sensors are contained on/within both the prosthetic components and
the bone cement (PMMA).
[0057] In various embodiments, these sensors may be positioned in a
variety of different patterns on the prosthetic components based on
their contact locations with respect to the surrounding bone
(femur, tibia and/or patella) and/or the surrounding bone cement
(if present). For example, they may be arranged in the pattern of
an X, as oval or concentric rings around the various components or
in various other patterns, in order to collect accurate data on the
physical contact between the tibial component and the tibia and/or
surrounding bone cement (if present), the femoral component and the
femur and/or surrounding bone cement (if present), and the patellar
component and the patella and/or surrounding bone cement (if
present). Contact sensors can also be dispersed within/arranged
within the bone cement (if present) so as to collect data on the
physical contact between the bone cement and the components of the
prosthesis (femoral, tibial and patellar) and/or between the bone
cement and the bone (femur, tibia, patella) itself.
[0058] Within various embodiments of the invention contact sensors
are placed on the tibial component, femoral component, and/or
patellar components of the knee prosthesis, and/or in the bone
cement securing the components of the prosthesis to the surrounding
bone, at a density of greater than one, two, three, four, five,
six, seven, eight, nine, or ten sensors per square centimeter, or,
per cubic centimeter of the prosthetic device component and/or per
cubic centimeter of bone cement.
[0059] Within other aspects of the invention methods are provided
for imaging a knee replacement or medical device as provided
herein, comprising the steps of (a) detecting the location of one
or more sensors in a knee replacement or medical device; and (b)
visually displaying the location of said one or more sensors, such
that an image of the knee replacement or medical device is created.
Within various embodiments, the step of detecting may be done over
time, and the visual display may thus show positional movement over
time. Within certain preferred embodiments the image which is
displayed is a three-dimensional image.
[0060] The imaging techniques provided herein may be utilized for a
wide variety of purposes. For example, within one aspect, the
imaging techniques may be utilized during a surgical procedure in
order to ensure proper placement and working of the knee
replacement or medical device. Within other embodiment, the imaging
techniques may be utilized post-operatively in order to examine the
knee replacement or medical device, and/or to compare operation
and/or movement of the device over time.
[0061] Within one embodiment the contact sensors 22 (22A, 22B, 22C)
can detect loosening of the prosthesis 10 and its connection to the
surrounding cement (if present) and/or bone. For example, the
contact sensors located on/in the tibial component and/or on/in the
bone cement around the tibial component (22B), can detect loosening
of the tibial component within the tibia; this can be detected
acutely during surgery and alert the surgeon that some
intra-operative adjustment is required. Progressive loosening of
the tibial component within the tibia over time (as compared to
post-operative levels) is a common complication that occurs when
bone loss takes place (e.g., due to a process known as osteolysis);
this too can be detected by the contact sensors on/in the tibial
component and/or on/in the surrounding bone cement. Furthermore,
contact sensors located between segments of the tibial component
(e.g. between the tibial plate and the tibial liner) can detect
abnormal movement, loosening, or wear between component segments;
these sensors can be "matching" (i.e. "paired" between adjacent
components) so as to also allow accurate fitting during (and after)
surgical placement.
[0062] Thus, in the embodiment of FIG. 5, a variety of contact
sensors are provided in order to monitor contact between the tibia
and the tibial component, between the femur and the femoral
component, between the patella and the patellar component, between
the complimentary segments of the individual prosthetic components,
and between the various articular surfaces present (medial and
lateral tibial-femoral joint; the patellar-femoral joint) of a
multi-compartmental or uni-compartmental prosthetic knee joint.
Specifically, full or partial dislocation (subluxation) of the
femoral prosthetic joint surface from the natural or synthetic
tibial joint surface (medial, lateral or both) of a prosthetic knee
is a common complication of knee replacement, often occurring
shortly after surgery (particularly during the post-operative
recovery period when the surrounding muscles and ligaments are
still healing from surgery). Contact sensors on the femoral
component articular surface and/or tibial component articular
surface can alert the patient and the healthcare provider if joint
dislocation or subluxation has occurred. This is of particular
value in the detection of subclinical partial or incomplete
dislocation (subluxation) of the knee joint which may not be
readily evident to the patient or the physician; this is of
greatest concern during early mobilization and post-operative
rehabilitation efforts. Additionally, contact sensors on the
various knee components can determine of the joint is functioning
and aligning (tracking) correctly during movement and activity.
This is particularly true with respect to the movement of the knee
cap, as accurate patellar tracking can be difficult to accurately
measure clinically; accurate measurement of patellar tracking, both
intra-operatively and post-operatively, would be beneficial.
[0063] In another embodiment shown in FIG. 6, one or more strain
gauges (or sensors) 26 are provided throughout the implant,
including strain gauges 26A distributed on and within the femoral
condyle prosthesis-bone interface, strain gauges 26B distributed on
and within the tibial bone--metal plate (and stem if present)
interface, and strain gauges 26C distributed on within the patellar
prosthesis (patellar "button")--patellar bone interface. In some
embodiments, the strain gauges are on the prosthetic components
themselves (tibial, femur and patellar segments), while in others
the strain gauges are contained on/within the bone cement (if
present) used to secure the prosthesis to the surrounding bone, and
in still other embodiments the strain gauges are contained
on/within both the prosthetic components and the bone cement
(PMMA).
[0064] In various embodiments, these strain gauges may be
positioned in a variety of different patterns on the prosthetic
components based on their contact locations with respect to the
surrounding bone (femur, tibia and/or patella) and/or the
surrounding bone cement (if present). For example, they may be
arranged in the pattern of an X, as oval or concentric rings around
the various components or in various other patterns, in order to
collect accurate data on the physical strain experienced by the
prosthetic components, the surrounding bone cement (if present),
and the surrounding bone (femur, tibia, patella) tissue.
[0065] Within various embodiments of the invention strain sensors
are placed on the tibial component, femoral component, patellar
prosthesis, and/or in the bone cement at a density of greater than
one, two, three, four, five, six, seven, eight, nine, or ten
sensors per square centimeter of the prosthetic components, or, per
cubic centimeter of PMMA bone cement.
[0066] The strain gauges 26 provide a different data point than the
contact sensors 22. The contact sensors 22 merely specify whether
there is current contact between adjacent structures and thus
provide a good indication of whether there is abutting contact
between two surfaces. However, they do not provide an indication of
the physical strain that is present in either the prosthetic
surfaces or the surrounding bone; on the other hand, the strain
sensors 26 output data is indicative of the mechanical strain
forces being applied across the implant which, if not corrected,
can be a harbinger of future loosening and prosthesis failure. In
addition, the strain gauges 26 may be of the type which indicates
the strain which is being exhibited between two surfaces, such as
between the tibial side and the bone, the femoral side and the
bone, the patellar side and the bone, between the prosthetic
components (tibial, femoral and patellar) and the bone cement, or
between the tibial, femoral, and patellar components
themselves.
[0067] As shown in FIG. 6, strain gauges 26 may be positioned at
various locations on the tibial component to detect strain
encountered between the tibial prosthesis and the surrounding
tibial bone (and/or bone cement if present). Many tibial prostheses
contain a stem that extends into the medullary canal of the tibia
to enhance anchoring and stability. A decrease in strain in the
tibial prosthesis and/or tibial bone cement may indicate that
conditions are present that could potentially lead to bone
resorbtion (loss) in all, or parts, of the tibial canal; bone
resorbtion can lead to loosening of the prosthesis, or to tibial
fracture (conversely, increased strain would favour bone growth in
the region). Therefore, the strain sensors can provide an
indication of the strain that is present in the tibial shaft and
measure the most important mechanical strain forces being applied
across the implant which, if mal-aligned or not corrected, have a
high probability of resulting in loosening and prosthesis failure.
An increase of strain may also indicate bone hypertrophy (growth),
which can be a source of pain. The same dynamic exists in the
interface between the femoral and patellar prosthetic components
(and/or bone cement) and the femur and patellar; strain gauges 26
of the present invention can be used to monitor for these purposes
as well. "Real life" strain information would not just be
beneficial to the doctor and patient, who could use the data to
determine the (positive and negative) effects of various activities
on prosthetic-bone health, but also to manufacturers who could use
it to design better prostheses.
[0068] In another embodiment shown in FIG. 7, one or more
accelerometers 27 are provided throughout the implant, including
accelerometers 27A distributed on and within the femoral condyle
prosthesis, accelerometers 26B distributed on and within the tibial
plate (and stem if present) and tibial liner, and accelerometers
27C distributed on within the patellar prosthesis (patellar
"button"). In some embodiments, the accelerometers are on/within
the prosthetic components themselves (tibial, femur and patellar
segments), while in others the accelerometers are contained
on/within the bone cement (if present) used to secure the
prosthesis to the surrounding bone, and in still other embodiments
the accelerometers are contained on/within both the prosthetic
components and the bone cement (PMMA).
[0069] In various embodiments, accelerometers may be positioned in
a variety of different patterns within/on the prosthetic components
based on their contact locations with respect to the surrounding
bone (femur, tibia and/or patella), the surrounding bone cement (if
present), the articular interface between the different prosthetic
components (tibial-femoral joint and the patellar-femoral joint),
and/or between sub-segments of a component (e.g. between the tibial
plate and the tibial liner). For example, they may be arranged in
the pattern of an X, as oval or concentric rings around, or within,
the various components or in various other patterns, in order to
collect accurate data experienced by the prosthetic components, the
surrounding bone cement (if present), and (by extension) the
surrounding bone (femur, tibia, patella) tissue.
[0070] Within various embodiments of the invention accelerometers
are placed on/within the tibial component, femoral component,
patellar prosthesis, and/or in the bone cement at a density of
greater than one, two, three, four, five, six, seven, eight, nine,
or ten sensors per square centimeter, or, per cubic centimeter of
the device and/or the bone cement.
[0071] Accelerometers provide the benefit of being able to detect
acceleration, vibration, shock, tilt, and rotation of various
components. They permit the ability to measure performance of the
prosthesis 10 under various conditions and over long periods of
time.
[0072] During knee replacement surgery, the prosthetic joint will
be moved through a full range of motion and stability testing to
assess prosthetic function and mobility prior to surgical closure.
The accelerometers 27 can provide the surgeon with accurate,
numeric, quantitative range of motion data at that time; this data
can be compared to expected values to assess efficacy of the
implantation surgery and can serve as a baseline value for
comparison to functional values obtained post-operatively. Any
abnormalities in vibration (indicative of an inadequate anchoring
of the prosthesis in the surrounding bone), tilt (indicative of
improper tracking and/or alignment of the tibial-femoral joint and
the patellar-femoral joint), rotation (indicative of dislocation or
subluxation), and/or range of motion can be addressed at this time
and allow the surgeon to make adjustments intra-operatively.
Shortly after the knee has been replaced, the leg will be mobilized
post-operatively, at first passively, then actively; shortly after
recovering from the procedure, the patient will begin gradual
weight bearing on the joint. The accelerometers 27 can measure the
movement and tracking of the knee joint during movement, including
during ambulation as the leg swings forward, hits the ground,
plants, is lifted off the ground, and the body is propelled
forward. In addition, the accelerometers can measure the impact of
the foot hitting the ground and the effect of the force being
transferred through the tibia to the knee joint and any vibration,
shock or rotation which may occur at different locations in the
prosthesis 10. As the patient continues to improve their range of
motion postoperatively, the acceleration experienced at different
locations in the prosthetic knee joint, can be monitored. It will
be expected that as the patient heals from the surgery, activity
levels will progressively increase, ambulation will improve and
increase, steps will be more rapid (and fluid) and, in addition,
greater stride length will be achieved with each step. The effects
of exercise and various activities can be monitored by the various
accelerometers 27 and can be compared to patient's subjective
experiences to determine which life activities are improving (or
inhibiting) post-operative recovery and rehabilitation.
[0073] In another embodiment shown in FIG. 8, one or more position
sensors 28 are provided throughout the implant, including position
sensors 28A distributed on and within the femoral condyle
prosthesis, position sensors 26B distributed on and within the
tibial plate (and stem if present) and tibial liner, and position
sensors 27C distributed on within the patellar prosthesis (patellar
"button"). In some embodiments, the position sensors are on/within
the prosthetic components themselves (tibial, femur and patellar
segments), while in others the position sensors are contained
on/within the bone cement (if present) used to secure the
prosthesis to the surrounding bone, and in still other embodiments
the position sensors are contained on/within both the prosthetic
components and the bone cement (PMMA).
[0074] In various embodiments, position sensors may be positioned
in a variety of different patterns within/on the prosthetic
components based on their contact locations with respect to the
surrounding bone (femur, tibia and/or patella), the surrounding
bone cement (if present), the articular interface between the
different prosthetic components (tibial-femoral joint and the
patellar-femoral joint), and/or between sub-segments of a component
(e.g. between the tibial plate and the tibial liner). For example,
they may be arranged in the pattern of an X, as oval or concentric
rings around, or within, the various components or in various other
patterns, in order to collect accurate data experienced by the
prosthetic components, the surrounding bone cement (if present),
and (by extension) the surrounding bone (femur, tibia, patella)
tissue.
[0075] Within various embodiments of the invention position sensors
28 are placed on the tibial component, femoral component, patellar
prosthesis, and/or in the bone cement at a density of greater than
one, two, three, four, five, six, seven, eight, nine, or ten
sensors per square centimeter, or, per cubic centimeter of the
device and/or bone cement.
[0076] Positional sensors 28 as described herein can be utilized to
provide accurate positional data (intra-operatively and
post-operatively), including the measurement of flexion and
extension, to enhance the accuracy of a physical exam by providing
3 dimensional data of the implant, to detect full and partial
dislocation (subluxation) of the tibial-femoral (knee) joint and/or
the patella-femoral joint, and to determine proper tracking of the
knee joint and the patella.
[0077] In another embodiment shown in FIG. 9, one or more contact
or pressure sensors 22 are provided throughout the implant,
including contact or pressure sensors 22A distributed on and within
(at various depths) the femoral condyle articular surface, contact
or pressure sensors 22B distributed on and within the tibial
articular liner (at various depths), and contact or pressure
sensors 27C distributed on within (at various depths) the patellar
articular prosthesis (patellar "button").
[0078] These sensors can also be utilized to detect progressive
erosion of the various articular surfaces. The sensors 22 may be
placed at progressive depths in the tibial, femoral and patellar
articular surface materials. They can also be activated when they
are uncovered (or when the covering surface is worn away), to
indicate the extent and depth of surface loss.
[0079] Such sensors can be utilized to estimate the effective
remaining lifespan of the implant, and to compare the performance
and design of different materials and implants.
B. Use of Knee Prosthesis, Medical Device or Kit to Deliver
Therapeutic Agent(s)
[0080] As noted above, the present invention also provides knee
prosthesis, medical devices and kits which comprise one or more
sensors, and which can be utilized to release a therapeutic agent
(e.g., a drug) to a desired location within the body. For example,
anti-restenotic drugs (e.g., paclitaxel, sirolimus, or an analog or
derivative of these), can be administered by a knee prosthesis,
medical device or kit. Within preferred embodiments one or more
sensors (e.g., pressure sensors, contact sensors, and/or position
sensors) can be utilized to determine appropriate placement of the
desired drug, as well as the quantity of drug that is released at
the desired site.
[0081] Within other embodiments of the invention a wide variety of
additional therapeutic agents may be delivered (e.g., to prevent or
treat an infection or to treat another disease state), including
for example: Anthracyclines (e.g., gentamycin, tobramycin,
doxorubicin and mitoxantrone); Fluoropyrimidines (e.g., 5-FU);
Folic acid antagonists (e.g., methotrexate); Podophylotoxins (e.g.,
etoposide); Camptothecins; Hydroxyureas, and Platinum complexes
(e.g., cisplatin) (see e.g., U.S. Pat. No. 8,372,420 which is
incorporated by reference in its entirety. Other therapeutic agents
include beta-lactam antibiotics (e.g., the penicillins,
cephalosporins, carbacephems and carbapenems); aminoglycosides
(e.g., sulfonamides, quinolones and the oxazolidinones);
glycopeptides (e.g., vancomycin); lincosamides (e.g, clindamycin);
lipopeptides; macrolides (e.g., azithromycin); monobactams;
nitrofurans; polypeptides (e.g, bacitracin); and tetracyclines.
C. Use of a Knee Prosthesis, Medical Device or Kit Having Sensors
to Measure Degradation or Wearing of an Implant
[0082] As noted above, within various aspects of the present
invention knee prosthesis, medical devices and kits which can
detect and monitor the degradation of an implant. For example,
within one embodiment of the invention a method is provided for
degradation of a knee replacement, medical device or kit,
comprising the steps of a) providing to a subject a knee
replacement, medical device or kit having sensors as described
herein, and b) detecting a change in a sensor, and thus determining
degradation of the knee replacement, medical device or kit. Within
various embodiments the sensor(s) can detect one or more
physiological and/or locational parameters. Within another
embodiment, the sensor(s) can detect contact, fluid flow, pressure
and/or temperature. Within yet another embodiment the sensors can
detect a location within the subject.
[0083] When a knee prosthesis degrades or is damaged, sensors can
detect a change so that a determination of damage and/or
degradation can be made. For example, a sensor that was previously
embedded within a polymer portion of a device, upon degradation may
be exposed to fluid forces, and pressures where none existed
before. If a sensor is eroded away, it may move within the synovial
cavity (i.e., away from where it had previously been implanted).
Hence, within preferred embodiments of the invention degradation
can be detected over a period of time.
D. Methods for Monitoring Infection in Knee Prosthesis, Medical
Devices and Kits
[0084] Within other embodiments knee prosthesis, medical devices
and kits are provided comprising one or more temperature and/or
metabolic sensors. Such knee prosthesis, medical device or kits can
be utilized to measure the temperature of the knee prosthesis,
medical device or kit, and in the local tissue adjacent to the knee
prosthesis, medical device or kit. Methods are also provided for
monitoring changes in temperature over time, in order to determine
and/or provide notice (e.g., to a patient and/or healthcare
provider) that an infection may be imminent.
[0085] In certain embodiments of the present invention, metabolic
and physical sensors can also be placed on or within the various
components of a total or partial knee prosthesis, medical device or
kit in order to monitor for rare, but potentially life-threatening
complications of knee prosthesis, medical device or kits. In some
patients, the knee prosthesis, medical device or kit and
surrounding tissues can become infected; typically from bacteria
colonizing the patient's own skin that contaminate the surgical
field (often Staphylococcus aureus or Staphylococcus epidermidis).
Sensors such as temperature sensors (detecting temperature
increases), pH sensors (detecting pH decreases), and other
metabolic sensors can be used to suggest the presence of infection
on or around the implant. For example, temperature sensors may be
included within one or more components of a knee prosthesis,
medical device or kit in order to allow early detection of
infection could allow preemptive treatment with antibiotics or
surgical drainage and eliminate the need to surgically remove the
knee prosthesis, medical device or kit.
[0086] Hence, within one embodiment of the invention methods are
provided for determining an infection associated with a knee
prosthesis, medical device or kit, comprising the steps of a)
providing to a subject a knee prosthesis, medical device or kit as
described herein, wherein the knee prosthesis, medical device or
kit comprises at least one temperature sensor and/or metabolic
sensor, and b) detecting a change in said temperature sensor and/or
metabolic sensor, and thus determining the presence of an
infection. Within various embodiments of the invention the step of
detecting may be a series of detections over time, and a change in
the sensor is utilized to assess the presence or development of an
infection. Within further embodiments a change of 0.5%, 1.0%, or
1.5% elevation of temperature or a metabolic factor over time
(e.g., 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4 hours, 12 hours, 1 day,
or 2 days) can be indicative of the presence of an infection (or a
developing infection).
[0087] Within various embodiments of the invention an antibiotic
may be delivered in order to prevent, inhibit or treat an infection
subsequent to its detection. Representative examples of suitable
antibiotics are well known, and are described above under Section B
(the "Therapeutic Agents").
E. Further Uses of Sensor-Containing Knee Prosthesis, Medical
Devices and Kits in Healthcare
[0088] Postoperative progress can be monitored (readings compared
from day-to-day, week-to-week, etc.) and the information compiled
and relayed to both the patient and the attending physician
allowing rehabilitation to be followed sequentially and compared to
expected (typical population) norms. Within certain embodiments, a
wearable device interrogates the sensors on a selected or
randomized basis, and captures and/or stores the collected sensor
data. This data may then be downloaded to another system or device
(as described in further detail below).
[0089] Integrating the data collected by the sensors described
herein (e.g., contact sensors, position sensors, strain gauges
and/or accelerometers) with simple, widely available, commercial
analytical technologies such as pedometers and global positioning
satellite (GPS) capability, allows further clinically important
data to be collected such as, but not restricted to: extent of
patient ambulation (time, distance, steps, speed, cadence), patient
activity levels (frequency of activity, duration, intensity),
exercise tolerance (work, calories, power, training effect), range
of motion (discussed later) and prosthesis performance under
various "real world" conditions. It is difficult to overstate the
value of this information in enabling better management of the
patient's recovery. An attending physician (or physiotherapist,
rehabilitation specialist) only observes the patient episodically
during scheduled visits; the degree of patient function at the
exact moment of examination can be impacted by a multitude of
disparate factors such as: the presence or absence of pain, the
presence or absence of inflammation, stiffness, time of day,
compliance and timing of medication use (pain medications,
anti-inflammatories), recent activity and exercise levels, patient
strength, mental status, language barriers, the nature of their
doctor-patient relations knee, or even the patient's ability to
accurately articulate their symptoms--to name just a few.
Continuous monitoring and data collection can allow the patient and
the physician to monitor progress objectively by supplying
objective information about patient function under numerous
conditions and circumstances, to evaluate how performance has been
affected by various interventions (pain control, exercise,
physiotherapy, anti-inflammatory medication, rest, etc.), and to
compare rehabilitation progress versus previous function and future
expected function. Better therapeutic decisions and better patient
compliance can be expected when both the doctor and the patient
have the benefit of observing the impact of various treatment
modalities on patient rehabilitation, activity, function and
overall performance.
[0090] The sensors used for the contact, strain, accelerometers and
position detection can be an acceptable type of those generally
available (see e.g., U.S. Pat. Nos. 7,450,332; 7,463,997 and
7,924,267 which describe various types of such sensors, including
MEMs sensors that can act as strain gauges, accelerometers and many
other sensing functions). The particular sensor described in U.S.
Pat. No. 7,450,332, which detects free fall of an object and motion
of an object with respect to a gravity field, would have particular
benefits in being able to detect and store all the forces acting on
the leg and the full motion of the leg, during passive and active
motion and when it is swinging in between steps, both before, after
and during impact with the ground.
[0091] As one example of the above, FIG. 4 illustrates the uses of
the sensors during a physical examination of the patient and the
different types of data which may be obtained from the sensors
which have been implanted according to the teachings herein. The
sensors provide evaluation data on the range of motion (ROM) of the
knee. Currently, ROM is usually measured clinically by the
physician passively moving the knee joint through a full range of
motion during physical examination and recording the results
(degrees of flexion, extension, abduction, adduction, external
rotation, internal rotation and rotation in flexion). Motion
sensors and accelerometers can be used to accurately determine the
full ROM of the prosthetic knee joint intra-operatively (in case
surgical adjustment is necessary), during post-operative physical
examination and during normal daily activities between visits. As
shown in FIG. 11A, one primary factor in the health of the knee is
the angle X that the patient is able to achieve at various times
during physical therapy as they recover from the surgery. As the
angle X becomes smaller and smaller, the doctor can be assured that
joint function is improving. By tracking angle X over time the
physical therapist can monitor the progress of the patient, assess
whether scar tissue formation, subluxation, or other pathology is
limiting/affecting ROM of the knee, and change/implement treatment
as needed. With the sensors installed as indicated herein, the
physical therapist or physician does not need to guess the angle
being achieved, rather, if the leg is positioned adjacent to a read
out computer, the exact angle can be known at the very moment that
the joint is being clinically evaluated. On the other hand, if X
does not continue to decrease, but remains large (or increases),
the physical therapist or physician can be alerted to problems
which the patient may be having in rehabilitation or delayed
recovery from the surgery and can investigate and/or take action
sooner rather than later. Similarly, the embodiment of FIG. 11B
indicates measurements that can be taken when the user holds the
leg at exactly a 90.degree. angle Y as shown. With the leg held
firmly at 90.degree., data can be collected from the various
sensors throughout the leg in order to determine the strain, the
contact locations, acceleration and other data. The position
sensors as used herein can alert the patient that the leg is held
at exactly 90.degree. so that the collecting of the data can be
accurate as data is collected at different times over several
months as the patient is monitored. While flexion and extension are
illustrated in the sited figures, it should be obvious to one of
skill in the art that data can also be collected for medial-lateral
joint stability and for anterior-posterior stability, subluxation
(if present) and tracking of the knee joint and the patella.
Additionally, ROM can also be monitored between patient visits by
interpreting ROM generated during daily activities when the patient
is at home.
[0092] As noted above, within other aspects of the invention
methods are provided for imaging a knee replacement or medical
device as provided herein, comprising the steps of (a) detecting
the location of one or more sensors in a knee replacement or
medical device; and (b) visually displaying the location of said
one or more sensors, such that an image of the knee replacement or
medical device is created. Within various embodiments, the step of
detecting may be done over time, and the visual display may thus
show positional movement over time. Within certain preferred
embodiments the image which is displayed is a three-dimensional
image. Within other embodiment, the imaging techniques may be
utilized post-operatively in order to examine the knee replacement
or medical device, and/or to compare operation and/or movement of
the device over time.
[0093] Certain exemplary embodiments will now be explained in more
detail. One particular benefit is the live and in-situ monitoring
of the patient's recovery and the implanted prosthesis 10. The
sensors as described herein are collecting data on a constant
basis, during normal daily activities and even during the night if
desired. Namely, the strain will be measured, collected and stored
on a regular basis over long periods of time with particular
measurements being taken at regular intervals. For example, the
contact sensors can obtain and report data once every 10 seconds,
once a minute, or once a day. Other sensors will collect data more
frequently, such as several times a second. For example, it would
be expected that the acceleration and position data would be
collected and stored several times a second. Other types of data
might only need to be collected by the minute or by the hour. Still
other sensors may collect data only when signaled by the patient to
do so (via an external signaling/triggering device) as part of
"event recording"--i.e. when the patient experiences a particular
event (e.g. pain, injury, instability, etc.)--and signals the
device to obtain a reading at that time in order to allow the
comparison of subjective/symptomatic data to objective/sensor data
in an effort to better understand the underlying cause or triggers
of the patient's symptoms. Since the tibial stem contains a large
internal portion which, might be hollow or a solid bar of metal,
this internal structure has more than sufficient space in order to
house one or more processor circuits, CPUs, memory chips and other
electrical circuits as well as antennas for sending and receiving
the data. The processors can be programmed to collect data from the
various sensors on any desired schedule as set by the medical
professional. All activity can be continuously monitored post
operation and the data collected and stored in the memory located
inside the implant.
[0094] A patient will generally have regular medical checkups. When
the patient goes to the doctor's office for a medical checkup, the
doctor will bring a reading device closely adjacent to the
prosthesis 10, in this example a knee replacement, in order to
transfer the data from the internal circuit inside the implant to
the database in the physician's office. The use of wireless
transmission using smartcards or other techniques is very well
known in the art and need not be described in detail. Examples of
such wireless transmission of data are provided in the published
patent applications and patents which have been described herein.
The data which has been collected based on the patient's movement
and use of the leg over the prior several weeks or even several
months is transferred in a few moments from the memory which is
positioned in the implant to the doctor's computer or wireless
device. The computer therefore analyzes the data for anomalies,
unexpected changes over time, positive or negative trends, and
other signs which may be indicative of the health of the patient
and the operability of the prosthesis. In addition, the physician
can collect data that details the record of all impacts to the
joint, including the magnitude and the direction of the
acceleration. If the physician locates a high acceleration event,
such as the patient falling, or other physical activities or
exercise, the physician can be alerted to inquire of the patient of
any problems they may have had during a fall or, alternatively,
warn the patient against too vigorous an activity which may
potentially cause damage to the knee implant. For example, if the
patient has decided to go skiing or jogging, the doctor will be
able to monitor the effect of such activity on the prosthesis 10,
including the accelerations and strains during the event itself.
The doctor can then look at the health of the prosthesis in the
hours and days after the event and compare it to data prior to the
event to determine if any particular event caused long term damage,
such a separation of the prosthesis from the surrounding bone
tissue or joint subluxation, or if the activities subjected the
prosthesis to stress/strain/impact forces beyond the manufacturer's
performance specifications for that particular artificial joint.
Data can be collected and compared with respect to the ongoing and
long term performance of the prosthesis from the strain gauges, the
contact sensors, the surface wear sensors, or other sensors which
may be present.
[0095] In one alternative, the patient may also have such a reading
device in their home which collates the data from the prosthesis on
a periodic basis, such as once per day or once per week. As
described above, the patient may also be able to "trigger" a device
reading (via an external signaling/triggering device) as part of
"event recording." Empowering the patient to follow their own
rehabilitation--and enabling them to see the positive (and
negative) effects of various lifestyle choices on their health and
rehabilitation--can be expected to improve compliance and improve
patient outcomes. Furthermore, their experience can be shared via
the web with other patients to compare their progress versus
expected "norms" for function and rehabilitation and alert them to
signs and symptoms that should be brought to their doctor's
attention. The performance of different implants can be compared in
different patients (different sexes, weights, activity levels,
etc.) to help manufacturers design better prostheses and assist
orthopedic surgeons in the selection of the right prosthesis for
specific patient types. Payers, patients, manufacturers and
physicians could all benefit from the collection of this
comparative information. Lastly, data accumulated at home can be
collected and transmitted via the Internet to the physician's
office for analysis--potentially eliminating unnecessary visits in
some cases and encouraging immediate medical follow-up in
others.
F. Generation of Power
[0096] Within certain aspects of the invention, a small electrical
generation unit can be positioned along an outer, or alternatively
an inner, surface of the implant. In particular, every time a user
takes a step, there is a release of pressure and an increase of
pressure inside the internal structure of the implant. Using the
appropriate piezoelectric materials or microelectric generators, a
small amount of electricity can be generated with each step that is
taken. The electricity can be stored in capacitors also mounted
inside the implant. The electricity can then be used to power the
sensors that are positioned at the various locations inside the
prosthesis.
[0097] A variety of techniques have been described for scavenging
power from small mechanical movements or mechanical vibration. See,
for example, the article entitled "Piezoelectric Power Scavenging
of Mechanical Vibration Energy," by U. K. Singh et al., as
published in the Australian Mining Technology Conference, Oct. 2-4,
2007, pp. 111-118. This paper provides examples of different types
of power scavengers which can produce electricity from very small
motion and store the electricity for later use. The above article
also describes embodiments in which pressure is applied and
released from the particular structure in order to produce
electricity without the need for motion, but rather as a result of
the application of high pressure. As explained in the embodiments
herein, force is applied to the internal structure of the implant
when the patient puts his weight on the leg during a step and such
force can produce more than enough electric power to operate all of
the sensors which are described herein. Other mechanisms that can
produce electricity from very small amounts of repetitive motion
are described U.S. Patent Application Publication No. 2010/0164705,
published on Jul. 1, 2010. This patent application describes
techniques by which energy can be harvested in the rotation of a
tire and then the harvested energy can be used to power a plurality
of different sensors and then, at selected time periods, the
selected sensors can output the collected data to a central
collection site. Other sensors of this type are described in issued
U.S. Pat. No. 7,603,894, entitled "Self-Powered Tire Monitoring
System."
[0098] In one preferred embodiment, the electrical generation
system is motionless and relies solely on pressure that is applied
during the step and the release of that pressure when the step is
completed and the leg swings free for the next step. Since there is
no motion, the patent will not feel any sensation due to small
changes in the position or length of the implant during the step.
Rather, the length is kept constant and the electricity is
generated by piezoelectric structures or by internal suspended
structures which do not form part of the support structure of the
implant.
[0099] After the electricity is generated by one or more
generators, the electricity is transmitted to any one of the
variety of sensors which is described herein. For example, it can
be transmitted to the contact sensors 22, the strain gauges 26, the
accelerometers 27, or the positional sensors 28. It may also be
transmitted to the other sensors described herein. The transmission
of the power can be carried out by any acceptable technique. For
example, if the sensor is physically coupled to the implant,
electric wires may run from the generator to the particular sensor.
Alternatively, the electricity can be transmitted wirelessly in the
same way that wireless smartcards receive power from closely
adjacent power sources using the appropriate send and receive
antennas. Such send and receive techniques of electric power are
also described in the publication and the patent applications and
issued U.S. patent previously described, all of which are
incorporated herein by reference.
G. Medical Imaging and Self-Diagnosis of Assemblies Comprising Knee
Replacements; Predictive Analysis and Predictive Maintenance
[0100] The present invention provides knee replacements which are
capable of imaging through the use of sensors over a wide variety
of conditions. For example, within various aspects of the invention
methods are provided for imaging a knee replacement (or portion
thereof (e.g., a medical device or kit as described herein) or an
assembly comprising a knee replacement, medical device or kit (as
described herein) with sensors, comprising the steps of detecting
the changes in sensors in, on, and or within a knee replacement,
medical device or kit over time, and wherein the knee replacement,
medical device or kit comprises sensors at a density of greater
than 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 10 sensors per square
centimeter. Within other aspects the knee replacement medical
device or kit comprises sensors at a density of greater than 1, 2,
3, 4, 5, 6, 7, 8, 9, 10 or 10 sensors per cubic centimeter. Within
either of these embodiments there can be less than 50, 75, 100, or
100 sensors per square centimeter, or per cubic centimeter. Within
various embodiments the at least one or more of the sensors may be
placed randomly, or at one or more specific locations within the
knee replacement, medical device, or kit as described herein. As
noted above, a wide variety of sensors can be utilized therein,
including for example, contact sensors, strain gauge sensors,
pressure sensors, fluid pressure sensors, position sensors, pulse
pressure sensors, blood volume sensors, blood flow sensors, blood
chemistry sensors, blood metabolic sensors, mechanical stress
sensors, and temperature sensors.
[0101] For example, a knee replacement, medical device, or kit
comprising sensors as described herein can be utilized to image
knee anatomy through sensors which can detect positional movement.
The sensors used can also include accelerometers and motion sensors
to detect movement of the knee replacement due to a variety of
physical changes. Changes in the position of the accelerometers
and/or motion sensors over time can be used as a measurement of
changes in the position of the knee replacement over time. Such
positional changes can be used as a surrogate marker of knee
anatomy--i.e. they can form an "image` of the knee replacement to
provide information on the size, shape and location of changes to
the knee replacement, and/or knee replacement movement/migration.
For example, loosening of the knee prosthesis can result in
unwanted movement of the prosthesis relative to bone in which it is
implanted during activity and weight bearing. By utilizing sensors
in the present invention, it is possible to determine the location
of the unwanted movement and the degree of movement present during
different motions and activities. Similarly, monitoring changes in
the joint space (i.e. the change in the space separating the
femoral and the tibial components) over time can be used as an
indicator of joint surface (femoral side and/or tibial side)
erosion and wear. Finally, following the movement of the sensors
throughout their range of motion can provide a dynamic "image" of
the joint; allowing the clinician to monitor both improvement and
decline in joint function (and surrounding tissues) over time.
H. Methods of Monitoring Assemblies Comprising Knee
Replacements
[0102] As noted above, the present invention also provides methods
for monitoring one or more of the knee replacement assemblies
provided herein. For example, FIG. 10 illustrates a monitoring
system usable with the knee replacement 10 as of the type shown in
any one of the Figures described above. The monitoring system
includes a sensor (e.g., 22, 26, 27 and/or 28) an interrogation
module 124, and a control unit 126. The sensor (e.g., 22, 26, 27
and/or 28) can be passive, wireless type which can operate on power
received from a wireless source. Such sensors of this type are well
known in the art and widely available. A pressure sensor of this
type might be a MEMS pressure sensor, for example, Part No.
LPS331AP, sold on the open market by STMicroelectronics. MEMS
pressure sensors are well known to operate on very low power and
suitable to remain unpowered and idle for long periods of time.
They can be provided power wirelessly on an RF signal and, based on
the power received wirelessly on the RF signal, perform the
pressure sensing and then output the sensed data.
[0103] In one embodiment, an electrical generation system (as
described above) is provided that can be utilized to power the
sensors described herein. During operation, as shown in FIG. 10, an
interrogation module 124 outputs a signal 128. The signal 128 is a
wireless signal, usually in the RF band, that contains power for
the sensor (e.g., 22, 26, 27 and/or 28) as well as an interrogation
request that the sensors perform a sensing. Upon being interrogated
with the signal 128, the sensor (e.g., 22, 26, 27 and/or 28) powers
up and stores power in onboard capacitors sufficient to maintain
operation during the sensing and data reporting. Such power
receiving circuits and storing on onboard capacitors are well known
in the art and therefore need not be shown in detail. The
appropriate sensing is carried out by the sensor (e.g., 22, 26, 27
and/or 28) and then the data is output from the sensor back to the
interrogation module 124 on a signal 130, where it is received at
an input port of the integration module.
[0104] According to one embodiment, sufficient signal strength is
provided in the initial signal 128 to provide power for the sensor
and to carry out the sensing operation and output the signal back
to the interrogation module 124. In other embodiments, two or more
signals 128 are sent, each signal providing additional power to the
sensor to permit it to complete the sensing operation and then
provide sufficient power to transfer the data via the signal path
130 back to the interrogation module 124. For example, the signal
128 can be sent continuously, with a sensing request component at
the first part of the signal and then continued providing, either
as a steady signal or pulses to provide power to operate the
sensor. When the sensor is ready to output the data, it sends a
signal alerting the interrogation module 124 that data is coming
and the signal 128 can be turned off to avoid interference.
Alternatively, the integration signal 128 can be at a first
frequency and the output signal 130 at a second frequency separated
sufficiently that they do not interfere with each other. In a
preferred embodiment, they are both the same frequency so that the
same antenna on the sensor can receive the signal 128 and send
signal 130.
[0105] The interrogation signal 128 may contain data to select
specific sensors on the knee replacement. For example, the signal
128 may power up all sensors on the knee replacement at the same
time and then send requests for data from each at different
selected times so that with one interrogation signal 128 provided
for a set time, such as 1-2 seconds, results in each of the sensors
on the knee replacement collecting data during this time period and
then, at the end of the period, reporting the data out on
respective signals 130 at different times over the next 0.5 to 2
seconds so that with one interrogation signal 128, the data from
all sensors 22 is collected.
[0106] The interrogation module 124 is operating under control of
the control unit 126 which has a microprocessor for the controller,
a memory, an I/O circuit to interface with the interrogation module
and a power supply. The control unit may output data to a computer
or other device for display and use by the physician to treat the
subject.
[0107] FIG. 11 illustrates the operation according to a preferred
embodiment within a subject. The subject has an outer skin 132. As
illustrated in FIG. 13, the interrogation module 124 and control
unit 126 are positioned outside the skin 132 of the subject. The
interrogation signal 128 passes through the skin of the subject
with a wireless RF signal, and the data is received on a wireless
RF signal 130 from the sensor (e.g., 22, 26, 27 and/or 28) back to
the interrogation module 124. While the wireless signal can be in
any frequency range, an RF range is preferred. A frequency in the
VLF to LF ranges of between 3-1300 kHz is preferred to permit the
signal to be carried to sufficient depth inside the body with low
power, but frequencies below 3 kHz and above 1300 kHz can also be
used. The sensing does not require a transfer of large amounts of
data and low power is preferred; therefore, a low frequency RF
signal is acceptable. This also avoids competition from and
inadvertent activation by other wireless signal generators, such as
blue tooth, cell phones and the like.
I. Collection, Transmission, Analysis, and Distribution of Data
from Assemblies Comprising Knee Replacements
[0108] FIG. 12 illustrates one embodiment of an information and
communication technology (ICT) system 800 arranged to process
sensor data (e.g., data from sensor (e.g., 22, 26, 27 and/or 28) of
any one of Figures provided herein). In FIG. 12, the ICT system 800
is illustrated to include computing devices that communicate via a
network 804, however in other embodiments, the computing devices
can communicate directly with each other or through other
intervening devices, and in some cases, the computing devices do
not communicate at all. The computing devices of FIG. 12 include
computing servers 802, control units 126, interrogation units 124,
and other devices that are not shown for simplicity.
[0109] In FIG. 12, one or more sensors (e.g., 22, 26, 27 and/or 28)
communicate with an interrogation module 124. The interrogation
module 124 of FIG. 12 is directed by a control unit 126, but in
other cases, interrogation modules 124 operates autonomously and
passes information to and from sensors 22. One or both of the
interrogation module 124 and control unit 126 can communicate with
the computing server 802.
[0110] Within certain embodiments, the interrogation module and/or
the control unit may be a wearable device on the subject. The
wearable device (e.g., a watch-like device, glasses, a wrist-band,
or other device that may be carried or worn by the subject) can
interrogate the sensors over a set (or random) period of time,
collect the data, and forward the data on to one or more networks
(804). Furthermore, the wearable device may collect data of its own
accord which can also be transmitted to the network. Representative
examples of data that may be collected include location (e.g., a
GPS), body or skin temperature, and other physiologic data (e.g.,
pulse). Within yet other embodiments, the wearable device may
notify the subject directly of any of a number of prescribed
conditions, including but not limited to possible or actual failure
of the device.
[0111] The information that is communicated between an
interrogation module 124 and a sensor (e.g., 22, 26, 27 and/or 28)
may be useful for many purposes as described herein. In some cases,
for example, sensor data information is collected and analyzed
expressly for the health of an individual subject. In other cases,
sensor data is collected and transmitted to another computing
device to be aggregated with other data (for example, the sensor
data from 22 may be collected and aggregated with other data
collected from a wearable device (e.g., a device that may, in
certain embodiments, include GPS data and the like).
[0112] FIG. 12 illustrates aspects of a computing server 802 as a
cooperative bank of servers further including computing servers
802a, 802b, and one or more other servers 802n. It is understood
that computing server 802 may include any number of computing
servers that operate individually or collectively to the benefit of
users of the computing servers.
[0113] In some embodiments, the computing servers 802 are arranged
as cloud computing devices created in one or more geographic
locations, such as the United States and Canada. The cloud
computing devices may be created as MICROSOFT AZURE cloud computing
devices or as some other virtually accessible remote computing
service.
[0114] An interrogation module 124 and a control unit 126 are
optionally illustrated as communicating with a computing server
802. Via the interrogation module 124 or control unit 126, sensor
data is transferred to (and in addition or alternatively from) a
computing server 802 through network 804.
[0115] The network 804 includes some or all of cellular
communication networks, conventional cable networks, satellite
networks, fiber-optic networks, and the like configured as one or
more local area networks, wide area networks, personal area
networks, and any other type of computing network. In a preferred
embodiment, the network 804 includes any communication hardware and
software that cooperatively works to permit users of computing
devices to view and interact with other computing devices.
[0116] Computing server 802 includes a central processing unit
(CPU) digital signal processing unit (DSP) 808, communication
modules 810, Input/Output (I/O) modules 812, and storage module
814. The components of computing server 802 are cooperatively
coupled by one or more buses 816 that facilitate transmission and
control of information in and through computing server 802.
Communication modules 810 are configurable to pass information
between the computer server 802 and other computing devices (e.g.,
computing servers 802a, 802b, 802n, control unit 126, interrogation
unit 124, and the like). I/O modules 812 are configurable to accept
input from devices such as keyboards, computer mice, trackballs,
and the like. I/O modules 812 are configurable to provide output to
devices such as displays, recorders, LEDs, audio devices, and the
like.
[0117] Storage module 814 may include one or more types of storage
media. For example, storage module 814 of FIG. 12 includes random
access memory (RAM) 818, read only memory (ROM) 810, disk based
memory 822, optical based memory 8124, and other types of memory
storage media 8126. In some embodiments one or more memory devices
of the storage module 814 has configured thereon one or more
database structures. The database structures may be used to store
data collected from sensors 22.
[0118] In some embodiments, the storage module 814 may further
include one or more portions of memory organized a non-transitory
computer-readable media (CRM). The CRM is configured to store
computing instructions executable by a CPU 808. The computing
instructions may be stored as one or more files, and each file may
include one or more computer programs. A computer program can be
standalone program or part of a larger computer program.
Alternatively or in addition, each file may include data or other
computational support material for an application that directs the
collection, analysis, processing, and/or distribution of data from
sensors (e.g., knee replacement sensors). The sensor data
application typically executes a set of instructions stored on
computer-readable media.
[0119] It will be appreciated that the computing servers shown in
the figures and described herein are merely illustrative and are
not intended to limit the scope of the present invention. Computing
server 802 may be connected to other devices that are not
illustrated, including through one or more networks such as the
Internet or via the Web that are incorporated into network 804.
More generally, a computing system or device (e.g., a "client" or
"server") or any part thereof may comprise any combination of
hardware that can interact and perform the described types of
functionality, optionally when programmed or otherwise configured
with software, including without limitation desktop or other
computers, database servers, network storage devices and other
network devices, PDAs, cell phones, wireless phones, glasses,
wrist-bands, pagers, electronic organizers, Internet appliances,
television-based systems (e.g., using set-top boxes and/or
personal/digital video recorders), and various other products that
include appropriate inter-communication capabilities. In addition,
the functionality provided by the illustrated system modules may in
some embodiments be combined in fewer modules or distributed in
additional modules. Similarly, in some embodiments the
functionality of some of the illustrated modules may not be
provided and/or other additional functionality may be
available.
[0120] In addition, while various items are illustrated as being
stored in memory or on storage while being used, these items or
portions of them can be transferred between memory and other
storage devices for purposes of memory management and/or data
integrity. In at least some embodiments, the illustrated modules
and/or systems are software modules/systems that include software
instructions which, when executed by the CPU/DSP 808 or other
processor, will program the processor to automatically perform the
described operations for a module/system. Alternatively, in other
embodiments, some or all of the software modules and/or systems may
execute in memory on another device and communicate with the
illustrated computing system/device via inter-computer
communication.
[0121] Furthermore, in some embodiments, some or all of the modules
and/or systems may be implemented or provided in other manners,
such as at least partially in firmware and/or hardware means,
including, but not limited to, one or more application-specific
integrated circuits (ASICs), standard integrated circuits,
controllers (e.g., by executing appropriate instructions, and
including microcontrollers and/or embedded controllers),
field-programmable gate arrays (FPGAs), complex programmable logic
devices (CPLDs), and the like. Some or all of the systems, modules,
or data structures may also be stored (e.g., as software
instructions or structured data) on a transitory or non-transitory
computer-readable storage medium 814, such as a hard disk 822 or
flash drive or other non-volatile storage device 8126, volatile 818
or non-volatile memory 810, a network storage device, or a portable
media article (e.g., a DVD disk, a CD disk, an optical disk, a
flash memory device, etc.) to be read by an appropriate input or
output system or via an appropriate connection. The systems,
modules, and data structures may also in some embodiments be
transmitted as generated data signals (e.g., as part of a carrier
wave or other analog or digital propagated signal) on a variety of
computer readable transmission mediums, including wireless-based
and wired/cable-based mediums. The data signals can take a variety
of forms such as part of a single or multiplexed analog signal, as
multiple discrete digital packets or frames, as a discrete or
streaming set of digital bits, or in some other form. Such computer
program products may also take other forms in other embodiments.
Accordingly, the present invention may be practiced with other
computer system configurations.
[0122] In FIG. 12, sensor data from, e.g., sensor (e.g., 22, 26, 27
and/or 28) is provided to computing server 802. Generally speaking,
the sensor data, represents data retrieved from a known subject and
from a known sensor. The sensor data may possess include or be
further associated with additional information such as the USI,
UDI, a time stamp, a location (e.g., GPS) stamp, a date stamp, and
other information. The differences between various sensors is that
some may include more or fewer data bits that associate the data
with a particular source, collection device, transmission
characteristic, or the like.
[0123] In some embodiments, the sensor data may comprise sensitive
information such as private health information associated with a
specific subject. Sensitive information, for example sensor data
from sensor (e.g., 22, 26, 27 and/or 28), may include any
information that an associated party desires to keep from wide or
easy dissemination. Sensitive information can stand alone or be
combined with other non-sensitive information. For example, a
subject's medical information is typically sensitive information.
In some cases, the storage and transmission of a subject's medical
information is protected by a government directive (e.g., law,
regulation, etc.) such as the U.S. Health Insurance Portability and
Accountability Act (KNEEPA).
[0124] As discussed herein, a reference to "sensitive" information
includes information that is entirely sensitive and information
that is some combination of sensitive and non-sensitive
information. The sensitive information may be represented in a data
file or in some other format. As used herein, a data file that
includes a subject's medical information may be referred to as
"sensitive information." Other information, such as employment
information, financial information, identity information, and many
other types of information may also be considered sensitive
information.
[0125] A computing system can represent sensitive information with
an encoding algorithm (e.g., ASCII), a well-recognized file format
(e.g., PDF), or by some other format. In a computing system,
sensitive information can be protected from wide or easy
dissemination with an encryption algorithm.
[0126] Generally speaking, sensitive information can be stored by a
computing system as a discrete set of data bits. The set of data
bits may be called "plaintext." Furthermore, a computing system can
use an encryption process to transform plaintext using an
encryption algorithm (i.e., a cipher) into a set of data bits
having a highly unreadable state (i.e., cipher text). A computing
system having knowledge of the encryption key used to create the
cipher text can restore the information to a plaintext readable
state. Accordingly, in some cases, sensitive data (e.g., sensor
data 806a, 806b) is optionally encrypted before being communicated
to a computing device.
[0127] In one embodiment, the operation of the information and
communication technology (ICT) system 800 of FIG. 12 includes one
or more sensor data computer programs stored on a computer-readable
medium. The computer program may optionally direct and/or receive
data from one or more knee replacement sensors implanted in one or
more subjects. A sensor data computer program may be executed in a
computing server 802. Alternatively, or in addition, a sensor data
computer program may be executed in a control unit 126, an
interrogation unit 124.
[0128] In one embodiment, a computer program to direct the
collection and use of knee replacement sensor data is stored on a
non-transitory computer-readable medium in storage module 814. The
computer program is configured to identify a subject who has a
wireless knee replacement inserted in his or her body. The wireless
knee replacement may include one or more wireless sensor
[0129] In some cases, the computer program identifies one subject,
and in other cases, two or more subjects are identified. The
subjects may each have one or more wireless knee replacements, and
each wireless knee replacement may have one or more wireless
sensors of the type described herein.
[0130] The computer program is arranged to direct the collection of
sensor data from the wireless knee replacement devices. The sensor
data is generally collected with a wireless interrogation unit 124.
In some cases, the program communicates with the wireless
interrogation unit 124. In other cases, the program communicates
with a control unit 126, which in turn directs a wireless
interrogation unit 124. In still other cases, some other mechanism
is used direct the collection of the sensor data.
[0131] Once the sensor data is collected, the data may be further
processed. For example, in some cases, the sensor data includes
sensitive subject data, which can be removed or disassociated with
the data. The sensor data can be individually stored (e.g., by
unique sensor identification number, device number, etc.) or
aggregated together with other sensor data by sensor type, time
stamp, location stamp, date stamp, subject type, other subject
characteristics, or by some other means.
[0132] The following pseudo-code description is used to generally
illustrate one exemplary algorithm executed by a computing server
802 and generally described herein with respect to FIG. 12:
TABLE-US-00001 Start Open a secure socket layer (SSL) Identify a
subject Communicate with a predetermined control unit Request
sensor data from the subject via the control unit Receive sensor
data If the sensor data is encrypted THEN decrypt the sensor data
Store encrypted data in the selected storage locations Aggregate
the sensor data with other sensor data Store encrypted data in the
selected storage locations Maintain a record of the storage
transaction Perform post storage actions End
[0133] Those skilled in the art will recognize that it is common
within the art to implement devices and/or processes and/or
systems, and thereafter use engineering and/or other practices to
integrate such implemented devices and/or processes and/or systems
into more comprehensive devices and/or processes and/or systems.
That is, at least a portion of the devices and/or processes and/or
systems described herein can be integrated into other devices
and/or processes and/or systems via a reasonable amount of
experimentation. Those having skill in the art will recognize that
examples of such other devices and/or processes and/or systems
might include--as appropriate to context and application--all or
part of devices and/or processes and/or systems of (a) an air
conveyance (e.g., an airplane, rocket, helicopter, etc.), (b) a
ground conveyance (e.g., a car, truck, locomotive, tank, armored
personnel carrier, etc.), (c) a building (e.g., a home, warehouse,
office, etc.), (d) an appliance (e.g., a refrigerator, a washing
machine, a dryer, etc.), (e) a communications system (e.g., a
networked system, a telephone system, a Voice over IP system,
etc.), (f) a business entity (e.g., an Internet Service Provider
(ISP) entity such as Comcast Cable, Qwest, Southwestern Bell,
etc.), or (g) a wired/wireless services entity (e.g., Sprint,
Cingular, Nextel, etc.), etc.
[0134] In certain cases, use of a system or method may occur in a
territory even if components are located outside the territory. For
example, in a distributed computing context, use of a distributed
computing system may occur in a territory even though parts of the
system may be located outside of the territory (e.g., relay,
server, processor, signal-bearing medium, transmitting computer,
receiving computer, etc. located outside the territory).
[0135] A sale of a system or method may likewise occur in a
territory even if components of the system or method are located
and/or used outside the territory. Further, implementation of at
least part of a system for performing a method in one territory
does not preclude use of the system in another territory.
[0136] In conclusion, prosthetic knee replacements utilizing a
variety of sensors can be utilized to serve a variety of critical
clinical functions, such as safe, accurate and less traumatic
placement and deployment of the knee replacement, procedural and
post-operative "real time" imaging of knee replacement and the
surrounding anatomy, the development of knee replacement
complications, and the patient's overall health status. Currently,
post-operative (both in hospital and out-patient) evaluation of
knee replacement patients is through patient history, physical
examination and medical monitoring that is supplemented with
diagnostic imaging studies as required. However, most of the
patient's recuperative period occurs between hospital and office
visits and the majority of data on daily function goes uncaptured;
furthermore, monitoring patient progress through the use of some
diagnostic imaging technology can be expensive, invasive and carry
its own health risks (the use of nuclear isotopes or certain dyes).
It can, therefore, be very difficult to accurately measure and
follow the development or worsening of symptoms and evaluate "real
life" knee replacement performance, particularly as they relate to
patient activity levels, exercise tolerance, and the effectiveness
of rehabilitation efforts and medications.
[0137] At present, neither the physician nor the patient has access
to the type of "real time," continuous, objective, knee replacement
performance measurements that they might otherwise like to have.
Being able to monitor in situ knee replacement function, integrity,
anatomy and physiology can provide the physician with valuable
objective information during office visits; furthermore, the
patient can take additional readings at home at various times (e.g.
when experiencing pain, during exercise, after taking medications,
etc.) to provide important complementary clinical information to
the doctor (which can be sent to the healthcare provider
electronically even from remote locations). From the perspective of
the patient, being able to monitor many of these same parameters at
home allows them to take a more proactive role in their care and
recovery and provide him or her with either an early warning
indicator to seek medical assistance or with reassurance.
[0138] In one alternative, the patient may have a reading device in
their home which collates the data from the knee replacement on a
periodic basis, such as once per day or once per week. In addition
to empowering the patient to follow their own rehabilitation--and
enabling them to see the positive (and negative) effects of various
lifestyle choices on their health and rehabilitation--such
information access can be expected to improve compliance and
improve patient outcomes. For example, within certain embodiments
the devices and systems provided herein can instruct or otherwise
notify the patient, or a permitted third-party as to deviations
(e.g., greater than 10%, 20%, 25%, 50%, 70%, and or 100%) from
normal, and/or, set parameters. Furthermore, their recovery
experience can be shared via the web with other patients to compare
their progress versus expected "norms" for function and
rehabilitation and alert them to signs and symptoms that should be
brought to their doctor's attention. From a public health
perspective, the performance of different knee replacements can be
compared in different patients (different sexes, disease severity,
activity levels, concurrent diseases such as hypertension and
diabetes, smoking status, obesity, etc.) to help manufacturers
design better knee replacements and assist physicians in the
selection of the right knee replacement for a specific patient
types. Payers, patients, manufacturers and physicians could all
benefit from the collection of this comparative information. Poor
and dangerous products could be identified and removed from the
market and objective long-term effectiveness data collected and
analyzed. Lastly, data accumulated at home can be collected and
transmitted via the Internet to the physician's office for
analysis--potentially eliminating unnecessary visits in some cases
and encouraging immediate medical follow-up in others.
[0139] The following are some specific numbered embodiments of the
systems and processes disclosed herein. These embodiments are
exemplary only. It will be understood that the invention is not
limited to the embodiments set forth herein for illustration, but
embraces all such forms thereof as come within the scope of the
above disclosure.
[0140] 1) A knee replacement prosthesis comprising:
[0141] at least one of a tibial component, a patellar prosthesis,
and a femoral component; and
[0142] a plurality of sensors coupled to at least one of the tibial
component, patellar prosthesis, and femoral component.
[0143] 2) The knee replacement prosthesis of embodiment 1 wherein
the plurality of sensors includes a sensor on the tibial
component.
[0144] 3) The knee replacement prosthesis of embodiment 1 wherein
the plurality of sensors includes a sensor on the patellar
prosthesis.
[0145] 4) The knee replacement prosthesis of embodiment 1 wherein
the plurality of sensors includes a sensor on the femoral
component.
[0146] 5) The knee replacement prosthesis according to any one of
embodiments 1 to 4 wherein said sensor is selected from the group
consisting of accelerometers, pressure sensors, contact sensors,
position sensors, chemical microsensors, tissue metabolic sensors,
mechanical stress sensors and temperature sensors.
[0147] 6) The knee replacement prosthesis according to embodiment 5
wherein said accelerometer detects acceleration, tilt, vibration,
shock and or rotation.
[0148] 7) The knee replacement prosthesis of embodiment 1 wherein
the plurality of sensors includes contact sensors positioned on the
femoral component.
[0149] 8) The knee replacement prosthesis of embodiment 1 wherein
the plurality of sensors includes a plurality of contact sensors
positioned on the patellar component.
[0150] 9) The knee replacement prosthesis of embodiment 1 wherein
the plurality of sensors includes a plurality of contact sensors
positioned on the tibial component.
[0151] 10) A medical device, comprising a femoral component of a
knee replacement prosthesis and a plurality of sensors coupled to
said femoral component.
[0152] 11) A medical device, comprising a patellar prosthesis of a
knee replacement prosthesis and a plurality of sensors coupled to
said patellar prosthesis.
[0153] 12) A medical device, comprising a tibial component of a
knee replacement and a plurality of sensors coupled to said tibial
component.
[0154] 13) The medical device according to any one of embodiments
10 to 12, wherein said sensors appear within and/or on the surface
of said medical device.
[0155] 14) The medical device according to any one of embodiments
10 to 13 wherein said sensor is selected from the group consisting
of accelerometers, pressure sensors, contact sensors, position
sensors, chemical microsensors, tissue metabolic sensors,
mechanical stress sensors and temperature sensors.
[0156] 15) The medical device according to embodiment 14 wherein
said accelerometer detects acceleration, tilt, vibration, shock and
or rotation.
[0157] 16) The knee replacement prosthesis according to any one of
embodiments 1 to 9 or medical device according to any one of
embodiments 10 to 15 further comprising:
[0158] an electronic processor positioned upon and/or inside at
least one of the tibial component, patellar prosthesis and/or the
femoral component that is electrically coupled to sensors.
[0159] 17) The knee replacement prosthesis or medical device of
embodiment 16 wherein the electric coupling is a wireless
coupling.
[0160] 18) The knee replacement prosthesis or medical device of
embodiment 17 further including:
[0161] a memory coupled to the electronic processor and positioned
upon and/or inside the at least one of tibial component, patellar
prosthesis and femoral component.
[0162] 19) The knee replacement prosthesis or medical device
according to any one of embodiments 1 to 18 wherein said sensor is
a plurality of sensors which are positioned on or within said knee
replacement at a density of greater than 1, 2, 3, 4, 5, 6, 7, 8, 9,
10 or 20 sensors per square centimeter.
[0163] 20) The knee replacement or medical device according to any
one of embodiments 1 to 19 wherein said sensor is a plurality of
sensors which are positioned on or within said knee replacement at
a density of greater than 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 20
sensors per cubic centimeter.
[0164] 21) A method comprising:
[0165] obtaining contact data from contact sensors positioned at a
plurality of locations between on and/or within a knee replacement
prosthesis or medical devices according to any one of embodiments 1
to 20 of a patient;
[0166] storing the data in a memory device located on or within the
knee replacement prosthesis or medical device; and
[0167] transferring the data from the memory to a location outside
the knee replacement prosthesis or medical device.
[0168] 22) The method according to embodiment 22 further
including:
[0169] obtaining strain data from strain sensors positioned at a
plurality of locations on the knee replacement prosthesis or
medical device of a patient;
[0170] storing the strain data in a memory located in said knee
replacement prosthesis or medical device; and
[0171] transferring the strain data from the memory to a memory in
located outside the knee replacement prosthesis or medical
device.
[0172] 23) The method according to embodiment 22 further
including:
[0173] obtaining contact data from contact sensors positioned in a
knee replacement prosthesis or medical device according to any one
of embodiments 1 to 19 of a patient;
[0174] storing the contact data in a memory located in the knee
replacement prosthesis or medical device; and
[0175] transferring the data from the memory to a memory in a
location outside of the knee replacement prosthesis or medical
device.
[0176] 24) A method comprising:
[0177] obtaining acceleration data from accelerometers positioned
at a plurality of locations on a knee replacement prosthesis or
medical device according to any one of embodiments 1 to 19 located
in-situ in the knee of a patient;
[0178] storing the acceleration data in a memory located in the
knee replacement prosthesis or medical device; and
[0179] transferring the acceleration data from the said memory in
the knee replacement prosthesis or medical device to a memory in a
location outside the knee replacement prosthesis or medical
device.
[0180] 25) A kit comprising the knee replacement prosthesis or
medical device according to any one of embodiments 1 to 19, further
comprising bone cement and/or bone screws comprising one or more
sensors.
[0181] 26) The kit according to embodiment 25 wherein said one or
more sensors are selected from the group consisting of
accelerometers, pressure sensors, contact sensors, position
sensors, chemical microsensors, tissue metabolic sensors,
mechanical stress sensors and temperature sensors.
[0182] 27) The kit according to embodiments 25 or 26 wherein said
sensors appear on said prosthesis or medical device at a density of
greater than 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 20 sensors per square
centimeter.
[0183] 28) The knee replacement, medical device, or kit according
to any one of embodiments 1-20 or 25-27 wherein the one or more of
the sensors are placed randomly within the knee replacement,
medical device or kit. Within other embodiments said sensors can be
placed at specific locations within the knee replacement, medical
device or kit.
[0184] 29) A method for detecting and/or recording an event in a
subject with a knee replacement or medical device as provided in
any one of embodiments 1 to 28, comprising the step of
interrogating at a desired point in time the activity of one or
more sensors within the knee replacement or medical device, and
recording said activity.
[0185] 30) The method according to embodiment 29 wherein the step
of interrogating is performed by a subject which has an implanted
knee replacement or medical device.
[0186] 31) The method according to embodiment 30 wherein said
recording is performed on a wearable device.
[0187] 32) The method according to any one of embodiments 29 to 31,
wherein said recording is provided to a health care provider.
[0188] 33) A method for imaging a knee replacement, medical device
or kit according to any one of embodiments 1 to 20 or 25 to 27,
comprising the steps of [0189] (a) detecting the location of one or
more sensors in a knee replacement, medical device, or kit
according to any one of embodiments 1 to 20 or 25 to 27; and [0190]
(b) visually displaying the location of said one or more sensors,
such that an image of the knee replacement or medical device is
created.
[0191] 34) The method according to embodiment 33 wherein the step
of detecting occurs over time.
[0192] 35) The method according to embodiment 34, wherein said
visual display shows changes in the positions of said sensors over
time.
[0193] 36) The method according to any one of embodiments 33 to 35
wherein said visual display is a three-dimensional image of said
knee replacement or medical device.
[0194] 37) A method for inserting a knee replacement, medical
device or kit according to any one of embodiments 1 to 20 or 25 to
27, comprising the steps of [0195] (a) inserting a medical device
according to any one of embodiments 1 to 20 or 25 to 27 into a
subject; and [0196] (b) imaging the placement of said medical
device according to the method of any one of embodiments 33 to
36.
[0197] 38) A method for examining a knee replacement, medical
device or kit according to any one of embodiments 1 to 20 or 25 to
27 which has been previously inserted into a patient, comprising
the step of imaging the knee replacement or medical device
according to the method of any one of embodiments 33 to 36.
[0198] 39) A method of monitoring a knee replacement, medical
device, or kit within a subject, comprising:
[0199] transmitting a wireless electrical signal from a location
outside the body to a location inside the subject's body;
[0200] receiving the signal at a sensor positioned on a knee
replacement, medical device, or kit according to any one of
embodiments 1 to 20 or 25 to 27 located inside the body;
[0201] powering the sensor using the received signal;
[0202] sensing data at the sensor; and
[0203] outputting the sensed data from the sensor to a receiving
unit located outside of the body.
[0204] 40) The method according to embodiment 39 wherein said
receiving unit is a watch, wrist band, cell phone or glasses.
[0205] 41) The method according to embodiments 39 or 40 wherein
said receiving unit is located within a subject's residence or
office.
[0206] 42) The method according to embodiments any one of
embodiments 39 to 41 wherein said sensed data is provided to a
health care provider.
[0207] 43) The method according to any one of embodiments 39 to 42
wherein said sensed data is posted to one or more websites.
[0208] 44) A non-transitory computer-readable storage medium whose
stored contents configure a computing system to perform a method,
the method comprising:
[0209] identifying a subject, the identified subject having at
least one wireless knee replacement, medical device, or kit
according to any one of embodiments 1 to 20 or 25 to 27, each
wireless knee replacement, medical device, or kit having one or
more wireless sensors;
[0210] directing a wireless interrogation unit to collect sensor
data from at least one of the respective one or more wireless
sensors; and
[0211] receiving the collected sensor data.
[0212] 45) The non-transitory computer-readable storage medium of
embodiment 44 whose stored contents configure a computing system to
perform a method, the method further comprising:
[0213] identifying a plurality of subjects, each identified subject
having at least one wireless knee replacement, medical device, or
kit, each wireless knee replacement, medical device, or kit having
one or more wireless sensors;
[0214] directing a wireless interrogation unit associated with each
identified subject to collect sensor data from at least one of the
respective one or more wireless sensors;
[0215] receiving the collected sensor data; and
[0216] aggregating the collected sensor data.
[0217] 46) The non-transitory computer-readable storage medium of
embodiment 44 whose stored contents configure a computing system to
perform a method, the method further comprising:
[0218] removing sensitive subject data from the collected sensor
data; and
[0219] parsing the aggregated data according to a type of
sensor.
[0220] 47) The non-transitory computer-readable storage medium of
embodiment 44 whose stored contents configure a computing system to
perform a method, wherein directing the wireless interrogation unit
includes directing a control unit associated with the wireless
interrogation unit.
[0221] 48) The non-transitory computer readable storage medium
according to any one of embodiments 44 to 47, wherein said knee
replacement, medical device, or kit is an assembly according to any
one of embodiments 1 to 20 or 25 to 27.
[0222] 49) The storage medium according to any one of embodiments
44 to 48 wherein said collected sensor data is received on a watch,
wrist band, cell phone or glasses.
[0223] 50) The storage medium according to any one of embodiments
44 to 49 wherein said collected sensor data is received within a
subject's residence or office.
[0224] 51) The storage medium according to any one of embodiments
44 to 50 wherein said collected sensed data is provided to a health
care provider.
[0225] 52) The storage medium according to any one of embodiments
44 to 51 wherein said sensed data is posted to one or more
websites.
[0226] 53) The method according to any one of embodiments 39 to 43,
or storage medium according to any one of embodiments 44 to 52,
wherein said data is analyzed. Within certain embodiments the data
can be analyzed to assess range of motion of a subject. Within
other embodiments, the data can be analyzed to assess or detect
bone erosion, inflammation, surface wear, and/or deterioration
and/or possible breakage or breakage of the knee prosthesis,
medical device or kit (or any portion thereof).
[0227] 54) The method or storage medium according to embodiment 53
wherein said data is plotted to enable visualization of change over
time.
[0228] 55) The method or storage medium according to embodiments 53
or 54 wherein said data is plotted to provide a three-dimensional
image.
[0229] 56) A method for determining degradation of a knee
replacement, medical device or kit, comprising the steps of a)
providing to a subject a knee replacement, medical device or kit
according to any one of embodiments 1 to 20 or 25 to 27, and b)
detecting a change in a sensor, and thus determining degradation of
the knee replacement, medical device or kit.
[0230] 57) The method according to embodiment 56 wherein said
sensor is capable of detecting one or more physiological and/or
locational parameters.
[0231] 58) The method according to embodiment 56 or 57 wherein said
sensor detects contact, fluid flow, pressure and/or
temperature.
[0232] 59) The method according to any one of embodiments 56 to 58
wherein said sensor detects a location within the subject.
[0233] 60) The method according to any one of embodiments 56 to 59
wherein said sensor moves within the body upon degradation of the
knee replacement.
[0234] 61) The method according to any one of embodiments 56 to 60
wherein the step of detecting is a series of detections over
time.
[0235] 62) A method for determining an infection associated with a
knee replacement, medical device or kit comprising the steps of a)
providing to a subject a knee replacement, medical device or kit
according to any one of embodiments 1 to 20 or 25 to 27, wherein
said knee replacement, medical device or kit comprises at least one
temperature sensor and/or metabolic sensor, and b) detecting a
change in said temperature sensor and/or metabolic sensor, and thus
determining the presence of an infection.
[0236] 63) The method according to embodiment 62 wherein the step
of detecting is a series of detections over time.
[0237] 64) The method according to embodiments 62 or 63 wherein
said change is greater than a 1% change over the period of one
hour.
[0238] 65) The method according to embodiments 62 to 64 wherein
said change is a continually increasing temperature and/or
metabolic activity over the course of 4 hours.
[0239] The various embodiments described above can be combined to
provide further embodiments. All of the U.S. patents, U.S. patent
application publications, U.S. patent applications, foreign
patents, foreign patent applications and non-patent publications
referred to in this specification are incorporated herein by
reference, in their entirety. Aspects of the embodiments can be
modified, if necessary to employ concepts of the various patents,
applications and publications to provide yet further
embodiments.
[0240] In general, in the following embodiments, the terms used
should not be construed to limit the embodiments to the specific
embodiments disclosed in the specification and the embodiments, but
should be construed to include all possible embodiments along with
the full scope of equivalents to which such embodiments are
entitled. Accordingly, the embodiments are not limited by the
disclosure.
* * * * *
References