U.S. patent application number 13/448318 was filed with the patent office on 2013-02-28 for precise femoral component positioning for hip replacement surgery.
The applicant listed for this patent is Brad L. Penenberg. Invention is credited to Brad L. Penenberg.
Application Number | 20130053904 13/448318 |
Document ID | / |
Family ID | 47744729 |
Filed Date | 2013-02-28 |
United States Patent
Application |
20130053904 |
Kind Code |
A1 |
Penenberg; Brad L. |
February 28, 2013 |
PRECISE FEMORAL COMPONENT POSITIONING FOR HIP REPLACEMENT
SURGERY
Abstract
A method for accurately positioning the acetabular cup in a
minimally invasive total hip arthroplasty (THA), comprising the
steps of (a) placing the cup in roughly the correct position in the
acetabulum using a acetabular component placement tool, (b) taking
a first abduction reading and a first anteversion reading using a
gyroscopic positioning unit aligned with the acetabular component
placement tool, (c) taking an image of at least a portion of the
cup using a radiography unit, (d) using the image to determine the
actual orientation of the cup and required position of the cup to
properly orient the acetabular component, (e) incrementally
altering the position of the cup by using a striking tool, (f)
taking new abduction and anteversion readings using the gyroscopic
unit to determine the relative movement of the cup caused by the
tapping, and (g) repeating any of the steps as necessary.
Inventors: |
Penenberg; Brad L.; (Los
Angeles, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Penenberg; Brad L. |
Los Angeles |
CA |
US |
|
|
Family ID: |
47744729 |
Appl. No.: |
13/448318 |
Filed: |
April 16, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13431944 |
Mar 27, 2012 |
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13448318 |
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61528744 |
Aug 29, 2011 |
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61567869 |
Dec 7, 2011 |
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Current U.S.
Class: |
606/86R |
Current CPC
Class: |
A61B 2034/2048 20160201;
A61B 17/32093 20130101; A61B 17/1703 20130101; A61B 2090/067
20160201; A61B 17/1746 20130101; A61B 17/320016 20130101; A61B
2017/320044 20130101; A61B 17/175 20130101; A61B 17/164 20130101;
A61B 17/3494 20130101; A61B 17/1668 20130101; A61F 2/4609 20130101;
A61B 17/1659 20130101 |
Class at
Publication: |
606/86.R |
International
Class: |
A61B 17/56 20060101
A61B017/56 |
Claims
1. A femoral broach tool, comprising: a. a connecting member
configured to receive a femoral broach, the connecting member
defining a central axis; b. a striking post connected to the
connecting member, the striking post defining a surface generally
perpendicular to the central axis; and c. a directional mount
attached to the connecting member to receive a directional device,
wherein the directional mount is configured to cause the
directional device to emit a visual guide parallel to the central
axis.
2. The femoral broach tool of claim 1 wherein the visual guide is
offset from the central axis and which offset can be adjusted
depending on the size of a patient and a thickness of soft tissues
adjacent to a wound.
3. The femoral broach tool of claim 1 wherein the directional mount
is angularly adjustable about the central axis.
4. The femoral broach tool of claim 1 wherein the directional
device is a laser pointer and the visual guide is a laser
light.
5. The femoral broach tool of claim 1 further comprising a
gyroscopic unit mountable to the connecting member.
6. The femoral broach tool of claim 1 wherein the femoral broach
tool is configured to receive a gyroscopic unit.
7. The femoral broach tool of claim 6 further comprising a
gyroscope mount attached to the connecting member, wherein the
gyroscope mount is angularly adjustable about the central axis.
8. A femoral broach tool, comprising: a. a connecting member
configured to receive a femoral broach, the connecting member
defining a central axis; and b. a directional mount attached to the
connecting member to receive a directional device, wherein the
directional mount is configured to cause the directional device to
emit a visual guide parallel to the central axis.
9. The femoral broach tool of claim 8 wherein the visual guide is
offset from the central axis and which offset can be adjusted
depending on the size of a patient and a thickness of soft tissues
adjacent to a wound.
10. The femoral broach tool of claim 8 wherein the directional
mount is angularly adjustable about the central axis.
11. The femoral broach tool of claim 8 wherein the directional
device is a laser point and the visual guide is a laser light.
12. The femoral broach tool of claim 8 further comprising a
gyroscopic unit mountable to the connecting member.
13. The femoral broach tool of claim 8 wherein the femoral broach
tool is configured to receive a gyroscopic unit.
14. The femoral broach tool of claim 8 further comprising a
gyroscope mount attached to the connecting member, wherein the
gyroscope mount is angularly adjustable about the central axis.
15. A method for preparing a femur for a total hip arthroplasty,
comprising: a. aligning a femoral broach tool along the femur with
a directional device emitting a guide to identify a line of attack
directed towards a chosen target; and b. displacing bone material
from the femur with the femoral broach tool by tapping the femoral
broach tool into the femur while maintaining the line of attack
according to the guide.
16. The method of claim 15 wherein the femoral broach tool
comprises: a. a femoral broach mounted to a broach handle, the
broach handle connected to a strike plate, and b. a mount connected
to the broach handle to support the directional device, wherein the
femoral broach tool defines a central axis and the line of attack
is parallel to the central axis.
17. The method of claim 15 wherein the mount is adjustably
connected to the broach handle in such a way as to allow the mount
to rotate about the broach handle as well as slide along the broach
handle.
18. The method of claim 15 wherein the mount comprises a lock to
fix the directional device in place.
19. The method of claim 15 further comprising adjusting the femoral
broach tool based on a reading from a gyroscopic unit.
20. The method of claim 15 wherein the femoral broach tool further
comprises a second mount to receive a gyroscopic unit.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This patent application is a continuation-in-part
application of U.S. patent application Ser. No. 13/431,944, filed
Mar. 27, 2012, entitled "Precision Hip Replacement Method," which
claims the benefit of U.S. Provisional Application No. 61/528,744,
filed Aug. 29, 2011, and U.S. Provisional Patent Application No.
61/567,869, filed Dec. 7, 2011. All applications are incorporated
herein by this reference thereto.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to the field of minimally invasive
surgical techniques for a joint replacement, and more particularly,
methods for accurately positioning components for hip or knee joint
replacement procedures.
[0004] 2. Description of the Related Art
[0005] During the course of total hip arthroplasty, acetabular and
femoral prostheses are placed. In order for the implants to
function up to their capacity, generally meaning greater than
twenty (20) years of clinical reliability, each component must be
placed in a specific position in relation to the patient's native
anatomy. Specifically, proper positioning of the acetabular
component in a hip replacement procedure appears to be crucial to
the long-term success of the surgery. What exactly constitutes
proper positioning of the acetabular component is the subject of
much debate. A commonly used range, established by Lewinnek et al.,
involves a cup position in which the abduction angle is within the
range of 30.degree. to 50.degree. and in which the anteversion
angle is within the range of 5.degree. to 25.degree.. Generally,
surgeons use radiographic techniques to achieve these angles.
[0006] Studies have shown, however, that a substantially large
percentage of surgeries result in cups that are not within this
range. This is especially true with respect to minimally invasive
surgical procedures. Callanan et al. surveyed 1952 hip
replacements, observing several prediction factors, and found that
only 48.7% resulted in acetabular cups within this range. Indeed,
of the 93 hip replacements in Callanan's survey that used minimally
invasive techniques, only 19.4% resulted in acetabular cups within
this range.
[0007] This supports the proposition that traditional techniques
have been considered by many to be unreliable for determining
proper positioning of the acetabular cup or femoral component.
[0008] A variety of tools are available, however, to assist the
surgeon in achieving correct component alignment. The so-called
traditional guides, or line-of-sight, have been in use for over 40
years and are very helpful, but not as reliable as one would
hope.
[0009] In the last 8-9 years, in an effort to improve reliability,
there have been attempts at using so-called navigation or computer
guidance systems relying on pre-operative CT scans to pre-load
information pertaining to the patient's anatomy, intraoperative
registration (a cumbersome and potentially tedious method to match
the patient's anatomy to the preloaded image), the placement of
multiple skeletal pins for orientation, and elaborate line-of-site
transmitters relying on complex computer algorithms to guide
component placement. Unfortunately, in spite of the promise of
improved results, the reluctance of patients to be exposed to a
significant amount of radiation during a CT scan, the significant
cost of such a test against a simple intraoperative x-ray
treatment, the total cost of the computer guidance system (many
hundreds of thousands of dollars plus the ongoing cost of support
annually as the machine is maintained and updated), the
incalculable cost to the healthcare system, and the patient of an
unpredictable workflow as system breakdown occurs frequently, add
operation time and potential risk to the patient, as well as
considerable cost. Consequently, this method has not been widely
adopted.
[0010] Furthermore, in spite of the existence of such tools, the
current success rate for acetabular component positioning is only
sixty percent (60%). Therefore, there is still a need to improve
the reliability and efficiency of instrumentation in achieving
these specific recognized optimal component positions.
SUMMARY OF THE INVENTION
[0011] One embodiment of the present invention comprises methods
for accurately positioning the acetabular cup in a minimally
invasive, or conventional, total hip arthroplasty (THA), comprising
the use of an elongated handle to place the cup in roughly the
correct position with respect to the acetabulum of the patient,
taking a first abduction reading and a first anteversion reading
using a gyroscopic positioning unit aligned with the handle, taking
an image of at least a portion of the cup using a radiography unit,
using the image to determine the actual orientation of the cup and
thereby the amount of movement in the abduction plane and in the
anteversion plane to properly orient the acetabular component,
incrementally altering the position of the cup by using a striking
tool and an elongated instrument to tap a contact surface at one or
more preformed impact receiving points, wherein the contact surface
is in mechanical communication with the cup, taking new abduction
and anteversion readings using the gyroscopic unit to determine the
relative movement of the cup caused by the tapping, and repeating
this striking step and this reading step until the cup has proper
abduction and anteversion readings.
[0012] In another embodiment of the present invention, the surgeon
may take additional intra-operative radiographic images during this
process as needed. Other embodiments may also involve taking
readings from a second gyroscopic unit aligned with a point on the
pelvis so that any movement of the pelvis in any direction during
surgery may be detected, quantified, and corrected. Such quantified
movements are then used to adjust the target abduction and
anteversion angles of the acetabular cup.
[0013] In some embodiments, a sterile surgical bag may be used to
enclose the gyroscopic unit(s) to allow them to be situated within
the operative field.
[0014] In further embodiments, employing the use of a portal
incision remote from the main incision to permit precise acetabular
bone preparation and cup implantation while employing a minimally
invasive surgical approach, the proper placement of the portal
incision is determined using an inside-out technique by using the
geometry of the acetabulum to direct a path along a trajectory
extending out from the plane formed by the face of the acetabulum
to a point on the skin that provides perpendicular access to the
acetabulum.
[0015] To assist with proper femoral bone preparation and
implantation, other embodiments may involve using a laser pointer
or other positioning device to more accurately verify that the
femoral broach is properly aligned with the femur while the surgeon
is preparing the femur to receive the femoral prosthetic. The laser
pointer may create a visible line or spot projecting generally
parallel to the line of attack of the femoral broach. This permits
more precise targeting of accepted anatomical landmarks such as the
center of the popliteal space.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Some elements in the drawings have been drawn not to scale
so that different features can be shown with better clarity.
[0017] FIG. 1 is a front view of an X-ray image of the pelvis
showing acetabular components on both sides of a patient in a
prescribed range of abduction angles as discussed above for
long-term wear and joint stability in keeping with one embodiment
of the present invention.
[0018] FIG. 2A is a perspective view of a tubular member in keeping
with one embodiment of the present invention utilizing a
directional device which is directed toward the center of the
acetabulum, trial cup, or attachment end of an acetabular component
placement tool, as discussed below, so that the directional device
may reliably point the tubular member away from the acetabulum
along a path that is generally perpendicular to the plane defined
by the face of the acetabulum. The cutting member may thereby be
directed through the tubular member and outward to the patient's
skin where the portal incision will be made effectively at the
optimal location, thereby creating access to the acetabulum along
this path through the newly created portal incision.
[0019] FIG. 2B is a diagram of a tubular member in keeping with
another embodiment in keeping with the present invention in which
the turn radius is minimized to reduce the size of the
cross-section necessary for the tubular member.
[0020] FIG. 2C is a perspective view of another embodiment of a
tubular member that does not require a flexible tool.
[0021] FIG. 3 is a diagram of an embodiment showing the tubular
member placed through a main incision in which the directional
device assists the surgeon by pointing to the middle of the
acetabulum (or trial cup, as discussed below, not shown). The
cutting member thereby optimally takes a path generally
perpendicular to the plane defined by the face of the acetabulum
while allowing the surgeon to avoid critical blood. Note, the
tissue such as nerves, tendons, ligaments, muscles, fat, and the
like have been removed for clarity.
[0022] FIG. 4 is a diagram of another embodiment showing a tubular
member in the vicinity of the pelvis bone and the acetabulum.
[0023] FIG. 5 is a diagram of a trough in keeping with one
embodiment in which a trough is used instead of or in conjunction
with a cannula.
[0024] FIG. 6 is a drawing showing an acetabular component
placement tool in keeping with one embodiment of the present
invention inserted into the main incision with a cannula (to permit
placement of, for example, an in-line impaction tool) resident in
the portal incision. The side hole in the handle of the acetabular
component tool is shown as round, but could readily be keyed or any
other shape to ensure the proper orientation of the gyroscope
holder that holds the gyroscopic unit.
[0025] FIG. 7 is a perspective view of another acetabular component
placement tool with a gyroscopic unit attached to the gyroscope
holder in keeping with one embodiment of the present invention.
[0026] FIG. 8 is a depiction of an acetabular component placement
tool in use.
[0027] FIG. 9 is a drawing of the surgeon observing an image from a
radiography unit in keeping with one embodiment of the present
invention showing one preferred viewpoint of the radiography unit
for use in combination with the gyroscopic unit in precisely
positioning the acetabular component about two axes, the abduction
angle and the anteversion angle.
[0028] FIG. 10A is a drawing of a strike plate in keeping with one
embodiment of the present invention.
[0029] FIG. 10B is a drawing of a strike plate placed within a
cavity of an acetabular component in keeping with one embodiment of
the present invention.
[0030] FIG. 11 is a drawing of another embodiment of the strike
plate showing a number of impact points to allow the selection of
the appropriate locations on the strike plate for the surgeon to
tap with a tapping instrument in order to achieve the desired
movement of the acetabular component in situ as it engages the
bone.
[0031] FIGS. 12A and 12B are diagrams of the relatively harder and
relatively softer bone regions that the acetabular component
encounters and that greatly add to the difficulty of precise
placement and positioning of the acetabular component. These
relatively hard and soft bone regions often cause the acetabular
component to move in a complex path in reaction to the tapping
described herein as part of one embodiment of the present
invention. As a result, these hard and soft bone regions are one
reason a strike plate having multiple impact points is particularly
critical to achieving proper orientation of the acetabular
component.
[0032] FIG. 13 is a perspective view of an embodiment of a
disengagement tool to remove an impaction tool.
[0033] FIG. 14A is a drawing of a smartphone being used as the
gyroscopic unit. It may have an open source or proprietary
gyroscope application. The unit may then be placed in a sterile bag
as shown for use during the surgical procedure.
[0034] FIG. 14B is a drawing of a smartphone gyroscopic unit in the
sterile bag of FIG. 10 wherein the bag is stretched tightly and any
excess is folded back and away from the screen so that the screen
of the smartphone (or iPod or the like) remains readily visible to
the surgeon and the touch-sensitive functionality of the screen
remains accessible through the bag membrane.
[0035] FIG. 15 is a perspective view of a second gyroscopic unit
fixed to a point on the patient's pelvis.
[0036] FIG. 16 is an image that may be produced by the combination
of the positional data from the first and second gyroscopic units
reflecting the position of the cup relative to the acetabulum and
the plane defined by the face of the acetabulum during a hip
replacement procedure in keeping with one embodiment of the present
invention.
[0037] FIG. 17 is a perspective view of a femoral broach handle
showing an adjustable mount for a pointer alignment device
extending laterally from the handle that can allow adjustments for
anteversion rotation of the broach and broach handle as it is
inserted and to maintain a pointer directed precisely along the
true posterior or true anterior surface of the femur. In keeping
with one embodiment of the present invention, this alignment
indicator--capable of indicating either or both of the broach
longitudinal direction and anteversion orientation--reduces the
risk of malposition of the femoral implant which can result in
incorrect sizing or femur fracture.
[0038] FIG. 18 is another perspective view of the femoral broach
handle of FIG. 17 in combination with a broach in place in keeping
with one embodiment of the present invention.
[0039] FIG. 19 is a side view of the femoral broach handle with a
laser pointer device attached in keeping with one embodiment of the
present invention.
[0040] FIG. 20 is a perspective view of the femoral broach tool in
use with a laser indicator light pointing toward the vicinity of
the popliteal space and a gyroscopic unit to read the anteversion
of the femoral broach in keeping with one embodiment of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0041] The detailed description set forth below in connection with
the appended drawings is intended as a description of
presently-preferred embodiments of the invention and is not
intended to represent the only forms in which the present invention
may be constructed and/or utilized. The description sets forth the
functions and the sequence of steps for constructing and operating
the invention in connection with the illustrated embodiments.
However, it is to be understood that the same or equivalent
functions and sequences may be accomplished by different
embodiments that are also intended to be encompassed within the
spirit and scope of the invention.
[0042] In general, minimally invasive techniques for total hip
arthroplasty require making a main incision in the hip area of the
patient to access the acetabulum of the pelvis, making a portal
incision (described by this author in prior disclosures) to
facilitate the proper positioning of an acetabular component,
properly positioning the acetabular component in the acetabulum by
making adjustments of the acetabular component through the main
incision and the portal incision, utilizing the main incision to
facilitate preparation of the femur to receive a femoral implant,
and preparing the femur with a femoral broach to receive the ball
that will be coupled with the acetabular component. One major goal
is to achieve the proper abduction angle and anteversion angle as
shown in FIG. 1.
[0043] One embodiment of the present invention involves an
intraoperative system and method of locating the optimal position
for the portal incision for a minimally invasive THA, properly
positioning the acetabular cup, and properly preparing the femur.
The portal incision in such an embodiment, the portal incision is
located by making a main incision to access an acetabulum of a
patient, using either a blunt or cutting member to forge a path
through the patient's tissues along a trajectory generally
perpendicular to the plane defined by the face of the acetabulum,
thereby identifying an appropriate portal incision location on the
patient's skin while allowing the surgeon to avoid numerous blood
vessels, muscles, tendons, and nerves in the process, making a
portal incision at this identified point on the patient's skin.
Then, the surgeon may use the direct, frontal access to the
acetabulum created by this portal incision and path to prepare the
acetabulum to receive an acetabular cup. This access may be further
secured and maintained by using a cannula, trough or spatula
device. In such instances, the surgeon may introduce the device to
maintain the channel and thereby protect the contiguous tissues
from additional injury by placing the device around the tip of the
blunt or cutting member and then guide the trough-like device
through the portal incision in into the forged path.
[0044] In some embodiments, the acetabular component or cup may
then be properly positioned to greatly improve the likelihood of
success and longevity of the component, including attaching the
acetabular cup to the end of an acetabular component placement tool
and using the acetabular component placement tool to place the cup
in roughly the correct position with respect to the pelvis of the
patient. Knowing the approximate position of the patient's pelvis
by virtue of the use of at least a semi-secure positioning device,
the surgeon may then take a first abduction and a first anteversion
reading using a gyroscopic positioning unit aligned with the
acetabular component placement tool. The surgeon may then use a
radiography unit to take an image of the pelvis containing the
newly placed cup and use this image to more accurately determine
the position of the cup.
[0045] In light of this true initial position, the surgeon may then
alter the position of the cup incrementally by using a striking
tool to tap a contact surface at one or more preformed impact
receiving points, wherein the contact surface is in mechanical
communication with the cup. The surgeon may taking new abduction
and anteversion readings to determine the how far the cup moved
relative to the initial position due to the tapping, and then
repeat the tapping and reading steps until the cup has reached a
proper abduction angle and anteversion angle as indicated by the
gyroscopic device display. The proper position for an acetabular
cup is defined as a position in which the abduction and anteversion
angles are within the predetermined acceptable ranges, as discussed
above and widely researched in the literature.
[0046] This method indeed, among other benefits, allows the surgeon
to properly position the cup without having to place any
positioning pins in or on the patient, thereby avoiding the pain,
risk of infection, and risk of pin movement that may accompany the
use of positioning pin. This technique also eliminates the use of
line of sight transmitters, e.g., RF type, which can be disrupted
during the typical movements of personnel in and around the
operative field, or by blood contacting the transmitters, or the
computer crashing.
[0047] In some embodiments of the present invention, the femur may
be prepared by a femoral broach mounted to a broach handle that
involves a striking post and a straight-line pointer means. The
means could be a light or laser pointer on an adjustable mount that
is mounted on the handle to allow moving the pointer around, toward
or away from, and/or along the handle or striking post. It can be
locked into place once properly positioned to point along an
optimal line, such as along the back of the patient's thigh
generally toward or medial to the popliteal space of the knee. The
surgeon then observes that the pointer continues to point at the
chosen target in the direction of this chosen line while he or she
repeatedly strikes the broach handle or striking post, thereby
ensuring that the femoral broach itself is properly oriented and
aligned with the femur.
I. Positioning the Portal Incision
[0048] In one embodiment of the present invention, the surgeon
locates the optimal position for the portal incision 244 by cutting
from the inside out, or from within the main incision, along a
trajectory away from the acetabulum 202 perpendicular to the plane
defined by the face of the acetabulum. This technique allows the
surgeon to locate a safe internal starting point and a safe path
directed out to the under surface of the patient's skin better
avoiding certain critical structures (veins, arteries, tendons,
muscle, sciatic nerve, other nerves), forging a safe path or course
around these structures while "sighting" or directing from inside
or from within the main incision 242. Then, once the starting
location is identified adjacent to these critical structures as
observed by the surgeon through the main incision 242, a rigid,
sharp or blunt or generally tubular body 100 is inserted adjacent
to and without damaging these structures. The body 100 may be
either curved as shown in FIGS. 2A and 2C, or angled as shown in
FIG. 2B. In some embodiments, the body 100 is generally tubular and
a flexible tool 108 is passed through the hollow of the body and
used to cut a path in the direction of the skin 240 distal to the
main incision 242 to create an acetabular portal incision 244 from
the inside out. In other embodiments, the body 100 itself has a
sharp or blunt front end that may be used to cut or forge a path in
the direction of the skin 240 distal to the main incision 242 to
create an acetabular portal incision 244 from the inside out. In
both scenarios, the path may be forged adjacent to and without
damaging these critical structures in a manner best achieved in
this inside-out method.
[0049] That is, by contrast, existing methods generally establish a
location for the acetabular portal incision from visual cues or
measurement made exclusively outside of the patient's body. With
such outside-in methods, however, a trajectory is created and
forged in which the surgeon cannot readily observe and avoid these
critical structures in order to alter the path to accommodate
variations in anatomy. These methods, therefore, typically cause
the surgeon to risk encountering critical blood vessels, muscles,
tendons, and nerves. Severing any of these can cause serious
complications and unnecessary bleeding. Indeed, most outside-in
methods lend to misjudging the proper location of the portal
incision due to the inaccuracies in the rotational orientation of
most common external visual guides. This error in rotation can even
lead to perforating the femur anteriorly or piercing the sciatic
nerve posteriorly. All of this may be avoided by the several
inside-out methods described herein in keeping with the present
invention.
[0050] In one embodiment of the present invention, therefore, a
tubular body 100 is equipped on one end with a linear sighting or
directional mechanism 104 to maintain a trajectory generally
perpendicular to the plane P of the face of the acetabulum 202. As
shown in FIG. 2A, in a preferred embodiment, the tubular body 100
is a hollow rod having a first portion 101 with a first opening
103, a second portion 102 adjacent to the first portion 103, the
second portion 102 having a second opening 107 in communication
with the first opening 103, and a bend 109 connecting the first and
second portions 101, 102. In other words, the first portion 101
bends into the second portion 102.
[0051] The first portion 101 of the tubular body 100 is generally
cylindrical and straight defining a first axis A and may serve as a
handle. The first opening 103 may be positioned at or near the top
or terminal end of the first portion 101 opposite the second
portion 102. In some embodiments, the first opening 103 may be on
the side surface of the first portion 101. In some embodiments, the
first opening 103 of the tubular body 100 may be on an auxiliary
shaft 111 protruding outwardly from the first portion 101 at an
acute angle. In some embodiments, the first portion may comprise
multiple openings for the surgeon to choose from.
[0052] The second portion 102 allows the tubular body 100 to be
properly positioned adjacent to the acetabulum in order to identify
and create a path towards the location of the portal incision 244.
The second portion 102 comprises a lead 115 and a directional tool
104 coaxially aligned with the lead, the lead and the directional
tool defining a second axis B. In some embodiments, the lead 115
comprises a second opening 107 perpendicular to the second axis B.
Due to the bend 109, the first axis A and the second axis B are
non-parallel to each other. In some embodiments, the first axis A
and the second axis B may form an acute angle with each other. In
some embodiments, the angle between axis A and axis B is between
25.degree. and 75.degree., in a preferred embodiment this angle is
within the range of 35.degree. and 65.degree.. In some embodiments,
the angle between axis A and axis B may be greater than 90.degree.
but less than 180.degree. as shown in FIG. 2C. This directs any
tool traveling parallel to or along the second axis to move towards
the surface of the skin 240 when the tubular body is properly
placed in the main incision 242.
[0053] In some embodiments, the bend 109 creates a tubular body 100
having an overall "J"-shape or hook-shape appearance as shown in
FIGS. 2A and 2B. Due to the small amount of space afforded by the
main incision in such surgeries, in some embodiments, the bend 109
may have a tighter curvature giving the external appearance of the
tubular body more of a "T"-, "L"-, or "V"-shape as shown in FIG.
2C.
[0054] That is, preferably, the main incision should be made as
small as possible. Therefore, utilizing a tubular body 100 with a
"tight" bend 109, such as in the "V"-shaped embodiment in FIG. 2C,
would minimize the overall lateral dimensions, or width, of the
tubular body 110; thereby, allowing for a smaller main incision.
With a "tight" bend, however, a flexible tool 118 may need to be
particularly flexible to make the turn as easily as in a hook
shaped bend. Therefore, the back wall of the bend 119 may instead
have a rounded or curved shape, gradually turning away from the
directional tool 114 and up toward the second opening 117 to guide
the flexible tool 118 to make the turn at the bend 119 and proceed
towards the second opening 117.
[0055] The tubular body 100 may further comprise a directional tool
104 attached to the second portion 102 in a way that it defines a
line of sight or a trajectory that is parallel to the second axis
B. In other words, the lead 115 and the directional tool 104 are
coaxially aligned. In some embodiments, the trajectory is along the
second axis B as shown in FIGS. 2A and 2B. In another embodiment,
the middle of the trial cup or the middle or the backside of the
attachment portion of the acetabular component placement tool may
comprise a feedback mechanism to facilitate this sighting by the
directional tool 104 of the tubular body 100 and ensure that the
tubular body 100 was in the correct position.
[0056] Alternatively, the directional tool 104 could be a laser
pointing device, emitting a visible laser light 106 or the like. In
some embodiments, the directional tool 104 may emit laser light 106
bidirectionally. For example, the directional tool 104 may be a
cylindrical device emitting laser light 106 from both ends in
opposite directions but along the same path. One end of the
directional tool 104 could then emit a laser light 106 pointing to
the middle of the acetabulum 202, the middle of the trial cup that
the surgeon may use for such positioning purposes, or the backside
of the attachment portion of the surgical tool 300 that attaches to
the trial cup and holds it in place for such positioning
purposes.
[0057] In such an embodiment, the opposite end of the directional
device 104 would then emit a laser light 106 along the trajectory
to illuminate a safe path to the portal incision 244 location.
Alternatively, the safe path may be illuminated by a lighting
device that is fed through the hollow of the tubular body 100, such
as an optical fiber or the like, and an imaging device may
similarly be fed through the tubular body 100.
[0058] In some embodiments, the directional tool 104 is configured
to be removable from the tubular body 100.
[0059] Due to the hollowness of the tubular body 100, the tubular
body 100 can receive a flexible tool 108 via the first opening 103
that can be fed through the first portion 101, to the second
portion 102, and out the second opening 107. Therefore, a diameter
of the flexible tool 108 is smaller than a diameter of the first
and second openings 103, 107. As the flexible tool 108 exits the
second opening 107 it follows the path of the trajectory
established by the directional tool 104 parallel to or along the
second axis B. The flexible tool 108 may comprise a cutting
instrument 150 at one end to cut through non-critical tissues or
move aside the critical tissues to create a path towards the skin
240 where the portal incision 244 is to be made. In some
embodiments, the flexible tool 108 may have a blunt end.
[0060] In addition, the flexible tool 108 may be a guide wire that
traverses the path established by the trajectory towards the portal
incision 244 while bypassing the critical tissue. A cannula,
scoopula, sleeve, spatula, or similar guide tool 120 can be passed
over or along the guide wire to maintain the path access to the
acetabulum and/or to put the guide tool 120 in the proper position
and orientation relative to the acetabulum for performing other
techniques in the surgery without damaging critical tissue. In this
embodiment, a cannulated, blunt, or sharp trocar, preferably
approximately 8-10 mm in diameter, or other suitable
tissue-protecting sleeve can be passed over this guide wire.
[0061] The flexible tool 108 can feed through the tubular body 100
and cut through the subcutaneous tissue and simply tent the skin
240, thereby identifying the portal location 244. While the skin
240 is tented, an apex is created and a 1-1.5 cm incision is made
at this apex. Alternatively, still in keeping with the present
invention, the surgeon may prefer to select a feed-through cutting
member that is sharp enough and rigid enough such that the cutting
member itself could actually cut through the skin at this optimal
incision point 244.
[0062] The cutting member 150 may then be fed through the skin a
short distance. This tubular body can be proportioned so that a
4-12 inch cannula 121, or a trough 120 as shown in FIGS. 3-5, can
then be placed over its tip at a distance of about 1 cm (or enough
to hold it in place) and the cannula 121 can then be led through
the same safe soft tissue path thus avoiding veins, which in the
common outside-in approach are typically severed and cause
unnecessary bleeding. In such embodiments, the tip 124 or cutting
member 150 of the flexible tool 108 may have a diameter that is
slightly smaller than the diameter of the remainder or main body of
the flexible tool 108 so that the junction where the main body
transitions into the tip 124 defines a rim or ledge 122 extending
radially outward from the outer surface of the tip 124, as
illustrated in FIG. 3.
[0063] The flange or ledge 122 may be slight, approximately 0.5 mm,
for example, and may be located about 1 inch or more or less from
the free end of the tip 124. The cannula 121 can be placed over the
pointed tip 124 as it penetrates the skin 240 or otherwise passes
through the portal incision until the cannula or spatula reaches
the ledge 122. The sharp edges of the thin metal or plastic spatula
or cannula 121 will thereby be covered as it is drawn through the
soft tissue pathway defined by the flexible tool 108.
[0064] In another embodiment, the working cannula can also simply
be fed over a smooth trocar that is directed along the safe
trajectory towards the skin. The skin is then tented, and an
incision is made to permit the trocar to be accessible for mounting
of and guidance of the cannula, spatula, or trough. In yet another
embodiment, the flexible tool 108 may be a thin-walled cannula or
tissue-protecting sleeve, such as having a wall thickness of
approximately 1-3 mm, an outer diameter of approximately 8-12 mm,
and a length of roughly 10-40 cm. In this way, the cannula or
trough member that maintains the just created path for use in
preparing the acetabulum may be introduced from the inside out.
[0065] In some embodiments, the tubular member 100 is indeed not
hollow but solid instead, as illustrated in FIG. 2C, having its own
pointed or blunt tip 126 projecting from the lead 115 that may be
used to forge the path along the generally perpendicular
trajectory. The second end 102 of the member 100 may then have a
ledge 128 between the lead 115 and the tip 126 that may then
receive the end of the cannula or spatula member 120 and thereby
act as a cannula introducer in a similar manner as discussed above.
In some embodiments, the ledge 128 of the second end 102 may taper
towards the tip 126. In such an embodiment, the main body of the
second end 102 may have a diameter that is slightly larger than a
cannula, scoopula, spatula, sleeve, or similar type of guide tool
120 and the tip 126 may have a diameter that is smaller than any
guide tool 120. This allows any guide tool 120 to slip over the end
126 and stop where the opening of the guide tool 120 is
substantially the same size as the diameter of the second end 102
(i.e., at the ledge 128). In this sense, a single second end 102
can be used for different guide tools 120 having different
sizes.
[0066] As mentioned above, the fixed trajectory created by the
outside-in technique does not afford the surgeon with the
opportunity to observe critical tissues and critical variations in
anatomy or a misjudged anteversion orientation of an externally
fixed sighting guide, all of which is avoided by the inside-out
technique disclosed herein with reference to one embodiment of the
present invention.
[0067] That is, this novel inside-out approach in this embodiment
of the present invention allows the surgeon to actually see these
vital structures from within and direct the potentially damaging
hook or trocar through less vital tissues, such as fatty tissues,
and particularly away from and around the vital structures and
tissues. This visualization of the soft tissue environment can be
additionally facilitated by optical fiber illumination and/or
digital imaging of the environment to determine the alternative
paths through the soft tissue along the trajectory generally
perpendicular to the plane defined by the face of the acetabulum.
In one embodiment, the illumination and imaging fibers can be
passed through the cannulated hook. The fiberoptic light may also
illuminate the skin from the inside out to indicate where to make
the portal incision. The incision can be made on the brightest
portion of the skin.
[0068] In some embodiments, the second portion 102 or 130 of the
tubular body 100 or 110 may further comprise a joint or a hinge 112
or 125 to connect the first portion 101 to the second portion 102.
The hinge 112 or 125 allows the directional device 104 or 114 and
the lead 115 or 127 (together defining axis B) to tilt in such a
way so as to change the angle between axis A and axis B. The tilt
of axis B relative to axis A may be controlled by a control
mechanism 113 or 129 to adjust the second portion 102 relative to
the first portion 101. Preferably, the control mechanism 113 or 129
is a dial located at the top of first portion 101 or 132 of the
tubular body 100 or 110 opposite the second portion 102 or 130. The
control mechanism 113 or 129 may also have a locking mechanism (not
shown) to lock the directional device 104 or 114 in place once the
proper angle has been established. The locking mechanism may
restrict or prohibit the movement of the control mechanism 113 or
129.
[0069] In other embodiments, the surgeon may tilt the first portion
101 or 132 of the tubular member during the procedure to manipulate
the blunt or cutting end through the soft tissue and create the
optimal path. In such embodiments, the surgeon may be able to
continuously or periodically adjust the directional device 104 or
114 using the control mechanism to insure that the blunt or cutting
end 150 continues to travel along the trajectory generally
perpendicular to the face of the acetabulum.
[0070] The control mechanism 113 or 129 may utilize a connecting
device (not shown), such as a flexible cable, rigid cable, rod, and
the like, to operatively connect to the directional device 104 or
114, the lead 115 or 127, and/or the hinge 112 or 125. Movement of
the control mechanism 113 or 129 can increase or decrease the
length of the connecting device so as to cause the directional
device 104 or 114 and the lead 115 or 127 to tilt. Use of the
control mechanism 113 or 129 allows the surgeon to make very
precise adjustments to the directional device 104 or 114 so as to
point the directional device 104 or 114 to the center of the
acetabulum 202 with minimal movement of the tubular body 100 or
110.
II. Positioning the Acetabular Component
[0071] As discussed above, proper positioning of the acetabular
component 400 is critical for the prosthesis to function up to its
capacity, but current methods are inaccurate, risky, and
time-consuming. An acetabular component 400 may be any device
designed to fit inside the acetabulum of a patient. By way of
example only, an acetabular component 400 may comprise a cup, a
trial cup, a reamer, a strike plate, and the like.
[0072] In one example, an acetabular component placement tool 300,
such as the standard cup holder/alignment guide shown in FIGS. 6
and 7, is commonly used in the medical profession to place and/or
align the acetabular component 400 in the typical "best guess"
position. Historically, because of the time consuming and
technically challenging nature of obtaining an intraoperative
x-ray, the true position of the component was not known until a
recovery room, or office, x-ray was taken. The generally achieved
success rate (achieving accurate positioning) is sixty percent
(60%) (Rubash, et al.). Unless a very severe error was identified,
nothing was done, and the patient carried the risk of early failure
of the hip arthroplasty. If the cup position was too steep, then
the plastic bearing surface could see excessive load and wear out
prematurely, requiring corrective operation. If the angle was too
shallow, then impingement of the femoral neck on the anterior rim
of the acetabulum could result in dislocation.
[0073] Using the very recent advances in imaging technology, i.e.,
the availability of computer and or digital radiography, now makes
it possible to obtain an accurate intraoperative image within a few
seconds, such as approximately ten (10) seconds, to approximately
one hundred twenty (120) seconds. This image (film or fluoroscopic
image, or possibly even CT or MRI) demonstrates the result of the
"first try" or "best guess" position. Thus, in one embodiment, this
image of the patient's anatomy is used in conjunction with a
gyroscopically enabled guide.
[0074] Having this intraoperative measurement, the surgeon now has
an opportunity to make an immediate correction. At present, the
sighting techniques with the traditional "best guess" instruments
required one or more additional x-rays to confirm the correction.
In addition, the traditional instruments were not constructed to
permit careful, precise, known degrees of adjustment.
[0075] The present invention offers a new method and tool
incorporating application for gyroscopic technology that provides a
significant improvement when compared with the current sighting
approach, i.e., sight, guess again, repeat the x-ray, and even
possibly requiring that these steps be repeated again.
[0076] The present invention also eliminates significant cost, a
critical factor in today's health care system. There is no
pre-operative CT scan, avoiding potentially damaging radiation
exposure, especially in younger patients and particularly women of
childbearing age. There is no upfront cost to the hospital in the
form of capital investments of up to a million dollars or more,
there is virtually no disruption of the desired workflow as the
required intraoperative image can be obtained in under two minutes,
interpreted in less than thirty seconds, and can be acted upon
immediately thereafter.
[0077] In the preferred embodiment, a gyroscopic unit 402 may be
placed in a sterile holder/container and affixed to a surgical tool
302, such as a straight or carefully angled cup holder/alignment
guide, as illustrated in FIG. 7. This upgrades the traditional
directional device to a metered tool providing improved estimates
during initial positioning of a prosthesis. An intra-operative
radiographic image of the then-present position is achieved during
initial estimated placement. The radiographic measurement is then
used as part of the method for achieving successful positioning or
the basis for making an intra-operative adjustment. Now, upon
obtaining measurements from the gyrometer and an image from the
intra-operative radiographic unit, the "best guess" positioning of
the acetabular component 400 relative to the acetabulum 202 can be
improved, the desired positioning can be determined and quantitated
as to the correction required for proper placement of the
acetabular component within the acetabulum.
[0078] In order to improve the accuracy, reduce the risk, and work
efficiently, besides the proper positioning of the portal incision
244, some embodiments of the present invention utilize gyroscopes
removably mounted on surgical tools 302 involved in acetabular
component placement, referred to as an acetabular component
placement tool 300, to provide a metered approach for adjusting the
acetabular component in the acetabulum. Examples of surgical tools
302 that can be used in the present invention include, but are not
limited to, a trial cup holder, a cup holder/alignment guide, an
impaction tool, a reamer unit, and the like.
[0079] In general, an acetabular component placement tool 300
comprises a surgical tool 302 used in positioning the acetabular
component 400, and a gyrometer or gyroscopic unit 402. The surgical
tool 302 has a proximal end 304 connected to a distal end 306. The
proximal end 304 is the end directly attached to or directly
associated with the acetabular component 400. The distal end 306 is
the end that the surgeon can grasp to move the tool 302 in order to
adjust the acetabular component 400. The distal or upper end 306
may comprise a handle 308 to facilitate movement of the surgical
tool 302.
[0080] In the preferred embodiment, a gyroscope 402 may be attached
to the distal end 306. In some embodiments, the gyroscope 402 may
be attached to the handle 308. It is anticipated, based on the cost
of gyroscopic technology, that only a nominal cost is required to
add such a metering system, i.e., the "gyrometer," to many existing
surgical instruments with only minor modifications. Indeed, in some
embodiments, a single gyroscope 402 may sense and display the
angular orientation of the acetabular component 400 in two or all
three of the traditional three (X, Y, and Z) planes. In other
embodiments, two or three separate gyroscopes 402 may be employed
to sense and indicate the angular orientation of the acetabular
component 400 in each of the two or three orthogonal metered
planes, separately. In this way, the surgeon can feel further
assured that each sensor will most accurately detect the
orientation or relative orientation within the chosen metered plane
(e.g., the Y plane), exclusive of any movement in either of the two
other planes (i.e., the X and Z planes).
[0081] In some embodiments, the gyroscope 402 may be integrally
formed with the surgical tool 302. In other embodiments, the
gyroscope 402 may be removably mounted to the surgical tool 302
using a gyroscope holder 404. The gyroscope holder 404 may be an
elongated rod having a first end 408 that attaches to the surgical
tool 302 and a second end 410 opposite the first end 408 that
attaches to the gyroscope 402. The surgical tool 302 may comprise a
plurality of holes 406 at different levels. The holes 406 can be of
any shape so long as the gyroscope holder 404 has a cross-sectional
configuration keyed to fit into the holes 406 securely. For
example, the holes 406 may be triangular, rectangular, hexagonal,
star-shaped, circular with a notch, and the like. One end 408 of
the gyroscope holder 404 would then have a cross-sectional shape
corresponding to the shape of the hole 406 so as to fit tightly and
securely into one of the holes 406 without being able to rotate.
This allows the surgeon to attach a gyroscope 402 to the surgical
tool 302 in such a way as to view the gyroscope readings.
Adjustment of the holder, and thus the gyroscope, could also be
carried out in order to facilitate a "zeroing effect," creating a
true read-out rather than a relative number.
[0082] In some embodiments, the gyroscope 402 may be incorporated
in a conventional mobile electronic device 1000 containing a
gyroscope 402, such as a smart phone, iPod touch, iPhone, personal
digital assistant, and the like as shown in FIGS. 14A and 14B.
These common mobile electronic devices can be installed with an
application for converting the yaw, pitch, and tilt or roll of the
gyroscope 402 into the abduction and anteversion of the acetabular
component 400, and the tile of the patient's pelvis.
[0083] The gyroscopic unit 402 may be a gyrometer, inclinometer,
accelerometer, magnetometer or compass, inertial sensor, GPS
(Global Positioning System) unit, or an optical, infrared, or RF
sensor. A gyroscope or gyrometer may be preferred in some
embodiments in that such units often measure relative movement in
two or three dimensions and in that many commercial devices have
gyrometer units that can provide high-resolution measurements.
[0084] The gyroscope 402 can measure its relative position in
three-dimensional space. Thus, any movement in the X, Y, and Z
direction can be read by the gyroscope 402. When the gyroscope 402
is attached to a tool or a patient's hip or thigh, one or more
reference angular readings of the tool or patient in
three-dimensional space may be communicated to the surgeon by the
gyroscope 402 to monitor any movement of the patient's pelvis. When
associated with a smart phone or other computing device, the
gyroscope 402 can display, announce, or otherwise indicate its
relative position. The surgeon can set the initial position as the
origin and calculate the amount of deviation from the origin
necessary for correct positioning and move the surgical tool
attached to the gyrometer 402 until the proper readings are
reached. Alternatively, the correct positioning may be established
as the origin and the gyrometer 402 may indicate the amount of
deviation from the origin. Therefore, the gyrometer 402 can be
moved until its readings reflect that it has reached the
origin.
[0085] As mentioned above, in some embodiments, a gyroscopic unit
402 may be superior to a standard inclinometer or magnetometer. A
standard inclinometer allows angular readings and correction
relative to only the vertical axis. This single reading by itself
cannot correctly position the acetabular component 400 to minimize
wear and reduce risk of dislocation. Similarly, a magnetometer
typically allows angular readings only relative to a near-linear
magnetic field, such as the Earth's magnetic field. The dual-axial
or tri-axial reading from the gyroscopic unit 402, by contrast, can
inform the surgeon as to the relative movement of both the
abduction angle (in a first plane) and the anteversion angle (in a
second plane perpendicular to the first plane), as well as the tilt
of the pelvis (in the third and remaining orthogonal plane).
[0086] Additional precision can be achieved if the pelvic tilt is
controlled. The holder may also have a hinge 702 and set screw 704
so that the surgeon may "zero" the anteversion angle reading simply
be adjusting the hinge 702 and then tightening down using the set
screw 704 when the anteversion reading is just as the surgeon
prefers. Examples of such hinge 702 and set screw 704 are
illustrated in FIG. 7.
[0087] In the preferred embodiment, the gyroscopic unit 402 may be
enclosed in a container 1002 to reduce and/or eliminate
cross-contamination between the gyroscopic unit 402 and the
patient. For example, the gyroscopic unit 402 may be wrapped inside
a sterile bag. This also makes cleaning and reusing the gyroscopic
unit 402 easy.
[0088] In yet another example that is still in keeping with some
embodiments of the present invention, two or more gyroscopes 402,
403 may be used for additional reference points to compensate for
movement of the patient's body, or the pelvis, rather than the
movement of the acetabular component 400. For example, a second
gyrometer 403 may be used as a second reference point. The second
gyrometer 403 may be mounted to a point on the patient's anatomy,
such as a point on the patient's pelvis 200, with a rod (not shown)
or some other type of holder that would facilitate proper
positioning of the acetabular component 400. In some embodiments,
the second gyrometer 403 may be attached directly to the patient's
anatomy without a rod, for example, with an adhesive that would
still permit the surgeon to read the second gyrometer 403. The
direct attachment may be removable so as to remove the second
gyrometer 403 when the surgery is complete. The surgeon may then be
able to verify to what degree the patient's pelvis 200 has moved
since the initial readings were taken from both the first and
second gyrometers 402, 403. The surgeon may then use this degree of
movement of the pelvis 200 to recalibrate the first gyrometer 402
or otherwise take such adjustments into account when calculating
his or her target readings on the first gyrometer 402, which, in
combination with the readings from the second gyrometer 403, is
reflective of the position of the acetabular component 400 in
relation to the acetabulum 202 of the patient's pelvis 200. In some
embodiments, first and second gyrometers 402, 403 may be in
communication with each other so that the first gyrometer 402
receives the readings from the second gyrometer 403 and the first
gyrometer 402 displays its readings regarding the positioning of
the acetabular component 400 after compensating or adjusting for
the movement of the pelvis as determined by the second gyrometer
403.
[0089] In some embodiments, the two gyrometers 402, 403 may
communicate with each other or with a local computer 800 so that
the changes in target readings of the first gyrometer 402 (i.e.,
the target position of the prosthetic cup) may be tracked,
communicated, and even displayed on a monitor 802 to indicate to
the surgeon how the patient's pelvis may shift during the
procedure. As shown in FIG. 16, computer software can transform the
readings and radiographic image of the actual, relative orientation
of the acetabulum 202 and acetabular component 400 into a two- or
three-dimensional image representation of the cup 300'; acetabulum
202'; and plane 203' defined by the face of the acetabulum
combination and display it on a screen 802 either on one of the
gyrometer units 402, 403 or on the local computer 800 in real time
so that the surgeon may get a good sense of how the acetabular
component 400 is located and moving relative to the acetabulum 202
during the procedure as the surgeon moves the acetabular component
400 in at least two dimensions relative to the acetabulum 202
(i.e., in the abduction and in the anteversion directions) and as
the patient's acetabulum 202 itself may move in any direction
during the procedure.
[0090] In some embodiments, instead of, or in addition to,
displaying the readings of the gyrometer 402, the gyrometer 402 may
announce the readings orally, or use a tone or some other aural
indicator, so that the surgeon does not have to take his eyes of
the patient to read the gyrometer 402. The gyrometer 402 can
announce either the current location so the surgeon knows where he
needs to move the acetabular component 400, or the gyrometer 402
can announce the type of movements the surgeon needs to make the
properly position the acetabular component 400.
[0091] Minor adjustments may be made with an impaction tool 600,
such as a strike plate as shown in FIGS. 10A, 10B, and 11. An
impaction tool 600 is configured to protect the acetabular
component 400 as the acetabular component is being struck for
proper positioning. In some embodiments, the impaction tool 600 may
comprise multiple striking ports 700, such as corrugations,
dimples, depressions, divots, recesses, and the like impaction
surface on the inside 602. The outside surface (not shown) of the
impaction tool 600 contacts the inside of the acetabular component
400 and creates a high-friction contact. Due to the high friction,
movement of the impaction tool 600 causes movement of the
acetabular component 400. Therefore, small increments of precise
adjustment of the acetabular component 400 can be made by tapping
on the impaction tool 600 without damaging the acetabular component
400. Such precise and incremental movements are critical,
particularly because of the combination of hard and soft bone
surfaces that the acetabular component 400 must engage with and
seat into. The impaction tool 400 also, in some embodiments, may
have regions through which the surgeon may see through to the bone
to confirm that the cup is fully seated.
[0092] In some embodiments, the impaction tool 600 may be a total
contact shell mating with the inner concavity of the acetabular
component 400 and secured via a central screw. The exposed surface
of this shell presents multiple striking ports 700 on the inner
face 602 to assist with fine adjustments of abduction or
anteversion as the acetabular component 400 is seated. The surgeon
may alternately strike the off center ports 700 and then the
central port, depending upon the changing position of the
prosthesis as it is seated. It is important to appreciate that the
bone density typically varies around the rim, along the walls and
at the dome of the prepared acetabulum as shown in FIGS. 12A and
12B. For example, the acetabulum may have hard areas 900 and soft
areas 902. Because of this variability, the prosthesis, if not
monitored and controlled as it is seating, will follow the course
of least resistance. Following that course creates a high risk of
component malposition. Traditional positioners provide only for a
central striking surface and a handle to generate a rotational
force at a point removed from the implant itself and therefore not
as precise as needed. The latter, central striking only technique,
typically requires disengagement and re-engagement as the cup
approaches final seating. This allows for the possibility of losing
some press fit as the bone is compressed with the first seating and
then can lose some "stiction friction" or press fit upon reseating
into the newly compressed bone.
[0093] In some embodiments, the impaction tool 600 may further
comprise a flange 608 at the opening of the impaction tool 600. The
flange 608 can be one continuous ring around the open edge of the
impaction tool 600 parallel to and in the plane of the strike plate
opening. Alternatively, the flange 608 may be short segmented
flanges intermittently spaced apart around the edge of the opening.
These flanges 608 can further serve as striking points to permit
greater angular momentum for moving the actual acetabular component
400. In some embodiments, the flanges 608 may comprise striking
ports 700, such as dimples, recesses, divots, depressions,
corrugations, or other modifications to facilitate striking of the
impaction tool 600. The striking elements in all cases are situated
and construed in a manner that protects the surfaces of the
acetabular prosthesis.
[0094] In some embodiments, the surgeon may tap the flange 608 with
the impaction tool 600 while the elongated handle remains attached
to the acetabular component. In other embodiments, the surgeon may
remove the elongated handle so that the surgeon may have numerous
other striking ports 700 to select to tap with a striking tool (not
shown). In such an embodiment, the strike plate or acetabular
component 400 can have a keying surface, such as one or more
component keying features 605, so that the surgeon may quickly and
easily re-seat the elongated handle within the acetabular component
202 from time to time to take new abduction and anteversion
readings from the gyroscope 402.
[0095] For example, the component 202 may also be keyed, such as
with one or more matching keying members 405, to mate with the
keying surface of the impaction tool 600 in order to re-seat the
proximal end 304 of the tool 300 in an identical orientation. The
gyrometer holder may also be keyed in order to re-seat it in an
identical orientation.
[0096] In some embodiments, a disengagement tool 1300 is provided
for the surgeon in case the acetabular component is so firmly
impacted that simply striking off center will not result in the
desired repositioning and may get stuck in the hard and soft bone
material 900, 902. That is, surgeons may find the cup or other
component may get stuck or frozen within the acetabulum making it
difficult or nearly impossible to adjust the component any further.
The surgeon may then use the disengagement tool 1300 shown in FIG.
13 to carefully and minimally, in a controlled manner, pry the
component, such as the impaction tool 600, loose so that he or she
may then re-institute the routine described above in a further
attempt to properly position the component using the radiographic
unit and/or the gyroscopes.
[0097] The disengagement tool 1300 may comprises a handle 1302 and
an arm 1304 attached to the handle 1302. At the end opposite the
handle 1302, the arm 1304 may branch or fork into multiple prongs.
The impaction tool 600 may comprise a plurality of fenestrations
604. A first prong 1306 may be configured to engage a first
fenestration. A second prong 1308 may be bent at an angle relative
to the arm 1304 and/or the first prong 1306 so as to engage a
second fenestration. In some embodiments, the first and second
prongs 1306, 1308 may be configured so that the first prong 1306
can engage the first fenestration while at the same time the second
prong 1308 is able to engage a second fenestration. This can
improve the leverage of the disengagement tool 1300 to more easily
remove the impaction tool 600. To further improve the leverage,
additional prongs may be added, one or more of the prongs may be
adjustable or extendable to accommodate a number of feature
configurations on the accessible surface of the impaction tool 600.
In some embodiments, the disengagement tool 1300 may be configured
to engage the striking ports 700 to remove the impaction tool
600.
[0098] The handle 1302 may be any shape. In some embodiments, the
handle 1302 may be planar. A planar surface could provide a
striking surface to controllably move or remove the impaction tool
600. In some embodiments, the handle 1302 may comprise contours so
as to be ergonomically shaped to facilitate grasping of the handle
1302.
Example 1
[0099] Generally, when using an acetabular component placement tool
300, start with the "Best Guess" approach (using the traditional
"Sighting" Guide approach, plus the Cup Holder/Alignment Guide),
obtain a radiographic or fluoroscopic image, and then use one
embodiment of the present invention to make precise
adjustments.
[0100] For example, once all of the proper incisions have been made
and the acetabular components 400 is initially put in place with an
acetabular component placement tool 300, the present settings of
abduction and anteversion are read from the gyroscopic device 402.
An imaging device 804, such as those used in radiographic or
fluoroscopic imaging, can be used to create a radiographic or
fluoroscopic image. For example, the imaging device 804 may be an
x-ray machine emitting x-rays 806. From the radiographic imaging,
the degree of abduction and anteversion needed for proper placement
of the acetabular component 400 can be determined. Then, as the
acetabular component placement tool 300 is shifted in the desired
direction(s), the gyroscopic device 400 displays the real time
changes in degrees so that the surgeon knows how much movement has
been made, and how much more movement in a particular direction is
still required. This reading, in reference to the starting
position, gives the surgeon precise affirmation that the ideal
position for stability and durability has been achieved.
[0101] The application of the gyroscopic indicator offers a
reading, a numerical equivalent, that records the position in space
that corresponds to the instant positioning confirmed on x-ray. The
correction can then be made. Precise adjustments in the two
critical planes (abduction and anteversion) can now be guided by
observing the gyroscopic readout. For example, the readout can be
calibrated to the amount of correction desired in each plane and
noted to be correct when reading zero for abduction and
anteversion. Another embodiment would be to set the gyroscope at
the measured abduction and anteversion and simply correct or change
the component position to the desired reading which would then
indicate the desired position has been achieved.
Example 2
[0102] In yet another embodiment, the best guess position can be
made more precise by applying the present invention to the standard
cup holder/alignment guide and, rather than relying on line of
sight, i.e., identifying a neutral or zeroing orientation that at
present is simply "sighted" in relation to operating room
structures (a corner of the room, a vertical line of tiles on the
wall, or any nearby straight vertical object) or imprecise
anatomical landmarks (patient's trunk, shoulder, opposite kidney).
That is to say, that the gyroscopic indicator is capable of
indicating true vertical for the upright part of the guide and true
zero or neutral for anteversion. After cup placement in the
orientation directed by the combined references of the present
invention connected (physically or remotely) to the recently
redesigned alignment guide, the guide is then removed. Screws or a
trial liner may then be placed. A femoral trial may also be placed
in the best guess position either before or after placing the
acetabular component. An x-ray or fluoroscopic image is then
obtained.
[0103] Those "corrected numerical" readings are used when placing
the actual acetabular component. The instrumented portion of the
reamer handle can then be transferred to the standard alignment
guide.
Example 3
[0104] This example is similar to Example 1 above, but including an
attached "gyrometer." The reamer basket (not shown) itself can act
as a surrogate for the acetabular component 400. The gyrometer 402
settings can then be noted, an x-ray taken, and any corrections
identified by measuring angles on the x-ray. This could be
considered a way of calibrating the gyrometer 402. When returned to
the same position (as indicated by the subsequent gyrometer 402
readout), correct acetabular component 400 positioning is then
achieved by placing the acetabular component 400 in position, which
results in corrected gyrometer readings.
[0105] By using a digital gyroscopic unit, the surgeon can quantify
the orientation in space of the acetabular component greatly
improving on the "best guess" orientation in which the surgeon
might otherwise eyeball the positioning. Clinical research to date
(including, Rubash, et al.) confirms a 40% error rate with current
"best guess" in which the surgeon does not use such digital
sighting or directional instruments.
[0106] The combination may create an advantage, including by
avoiding the need for the unreliable "line of sight" relative
referencing or the booting and rebooting of a computer, both of
which take substantial time and have been cumbersome and
unreliable. Indeed, these cumbersome and unreliable techniques have
been abandoned at many centers. As stated, forty percent (40%) of
the time, the position will be outside of the desired range and a
correction will be desirable. The data indicates that the success
rate using the intraoperative imaging and adjustment methods of the
present invention can be improved from sixty percent (60%) to
almost ninety-nine percent (99%)--and this significant success rate
may be produced using minimally invasive surgery procedures.
[0107] Some embodiments of the present invention also may eliminate
the need for reference pins in the pelvis as such pins can loosen,
change position, and diminish precision. The pin sites can become
infected and require treatment with costly and risky antibiotics. A
persistent pin site infection could result in migration of bacteria
to the new prosthesis with disastrous results. While placing pins
there is risk to nearby nerves and blood vessels. Numbness,
weakness, or unnecessary blood loss could occur. There is also a
price to pay in terms of time and materials. Clearly, avoiding
reference pins offers a significant advantage.
III. Positioning the Femoral Broach
[0108] In some embodiments of the present invention, the femur 220
is prepared by a femoral broach tool comprising a femoral broach
1401. The femoral broach 1401 may be mounted to a broach handle
1400, which comprises an elongated connecting member 1402. A
striking surface, platform, or striking post 1403 then may be
connected either to the connecting member 1402 or directly to a
portion of the femoral broach 1401 to allow the surgeon to strike
the striking post repeatedly until he or she has displaced the
appropriate amount of bone material from the femur to leave room
for the prosthesis and any associated mounting structures and
cementing material.
[0109] The lengthwise orientation of the femoral broach 1401 during
this process is critical to the successful preparation of the femur
220 and ultimate positioning of the prosthesis. In previous
methods, the surgeon lined up either the connecting member 1402,
the striking post 1403, or the hammer itself with line of sight
methods previously disclosed by Applicant in considerable detail.
In short, this often entails envisioning the femoral broach 1401 to
be in line with the striking post 1403 and attempting to keep the
striking post 1403 therefore in line or parallel to some straight
line along the patient's leg or other straight line in the
operating room that serves as a proxy to the centerline of the
patient's femur 220.
[0110] As shown in FIGS. 17 through 20, another aspect of the
present invention is the femoral broach handle 1400 being equipped
with a more precise alignment means to visibly align the femoral
broach 1401 during the bone displacement. The femoral broach handle
1400 comprises an elongated connecting member 1402 defining a
central axis C (which defines the line of attack), attached to a
striking surface, platform, or post 1403, to hold and drive the
femoral broach 1401 into the femur, and an adjustable mount 1404.
The adjustable mount 1404 is connected to the connecting member
1402 in such a way as to allow the adjustable mount 1404 to rotate
about the connecting member 1402 as well as slide up and down the
connecting member 1402.
[0111] The adjustable mount 1404 comprises a post 1406 and a lock
1408 to receive and secure a pointing device 1500, such as a laser
pointer. The post 1406 may also be telescopic to adjust the
distance of the pointing device 1500 relative to the connecting
member 1402. Due to the adjustable mount 1404, the laser pointer
1500 may be offset from the central axis C of the femoral broach
1401 and connecting member 1402, and it is oriented to emit a light
or laser generally parallel to this central axis C. In some
embodiments, the surgeon then can adjust the positioning of the
pointer 1500 so that the light emitted from it runs along the back
of the thigh approximately toward the popliteal space 602, strikes
the back of the thigh near the region of the popliteal space 602,
strikes the back of the calf just past the region of the popliteal
space 602, or strikes any other desired precise reference point
that guides broach and the prosthesis orientation.
[0112] The mount 1404 for the pointer 1500 may be adjustable in a
number of ways relative to the connecting member 1402 to
accommodate the surgical procedure. In one such embodiment, for
example, the mount 1404 may be a collar rotatably mounted to the
connecting member 1402, such that it can be rotated about the
central axis C of the connecting member 1402. The surgeon may
simply rotate the offset mounting arm about the central axis C of
the connecting member 1402 and then fix the pointer at an
appropriate angle using the lock 1408, such as a set screw or the
like, to indicate the anteversion angle as the broach seeks the
desired neutral position in the femoral canal. The mount 1404 may
also be slidable along the connecting member 1402 so as to adjust
the distance from the broach 1401. The mount 1404 may also have a
tilting capability to allow the laser pointer 1500 to be adjusted
so as to be parallel to the connecting member 1402.
[0113] In this way, the pointer 1500 may be adjusted to visibly
maintain the central axis C in any preferred anteversion angle,
regardless of the anteversion angle of the handle 1400 so that the
surgeon can project the laser light 1600 directly over the
posterior or anterior femur while orienting the broach 1401 in the
same or any other desired anteversion angle. The surgeon then
observes that the pointer 1500 continues to point at the chosen
target in the direction of this central axis C of the connecting
member 1402 as he or she repeatedly strikes the striking post 1403
or surface of the broach handle, thereby being certain that the
central axis C of broach 1401 itself is properly oriented and
aligned with the central axis of the femur.
[0114] In one preferred embodiment, therefore, the anteversion
angle of the femoral broach may be monitored, and in fact a
gyroscopic unit 402 may be mounted to the broach handle 1400 in a
similar fashion as discussed above with respect to the handle 1400
for the acetabular component 200. As illustrated in FIG. 20, there
may be a mounting arm 1407 having a lock 1411 as well as a pivot
means 702 and locking means 704 so that the anteversion of the
broach may be zeroed intraoperatively. Furthermore, a second
gyroscopic unit 403 may be temporarily mounted to the patient's
body, such as the thigh or knee region, as a reference reading to
assist with a precise anteversion reading for the broach 1401 even
if the patient's leg happens to move or shift during the
procedure.
[0115] This is especially important when placing a cemented implant
that is not guided by the prepared bone envelope. That is, the
handle and alignment means may hold the femoral component in the
proper longitudinal alignment while the cement sets so that any
forces on the femoral component as the cement begins to set may be
overcome by the surgeon. The surgeon may additionally wish to
maintain a given anteversion angle for the femoral component using
the same handle and alignment means.
[0116] Whether employed in the setting of the femoral prosthesis or
not, the anteversion readings for the femoral broach and/or
prosthesis itself can be used to calculate or modify the target
anteversion range for the acetabular component 200 unique for the
given patient. That is, the anteversion angle for the femoral
component can fall within a wide range, ordinarily between
0.degree. and 70.degree., and typically is dictated by the contours
of the patient's femur. This may be due to a number of factors
unique to each patient. As a general rule, therefore, the
anteversion angle of the acetabular component normally is more
easily varied than the anteversion angle of the femoral
component.
[0117] The actual angle of anteversion of the femoral component for
most patients can affect what is the appropriate target range for
the anteversion angle of the acetabular component for a hip
replacement to have a successful longevity. Typically, the larger
the anteversion angle of the femoral component, the larger the
anteversion angle needs to be for the acetabular component, leading
to increasing the target acetabular anteversion angle to within a
range of 20 to 25, where the patient's femoral anteversion angle is
on the higher end of the above-mentioned range.
[0118] While the present invention has been described with regards
to particular embodiments, it is recognized that additional
variations of the present invention may be devised without
departing from the inventive concept.
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