U.S. patent application number 15/748616 was filed with the patent office on 2020-03-26 for systems, devices, and method for the treatment of osteoarthritis.
The applicant listed for this patent is Cala Health, Inc.. Invention is credited to Daniel Lev Coleman, Scott Lee Delp, Samuel Richard Hamner, Kathryn H. Rosenbluth, Peter Bradley Shull, Serena HanYing Wong.
Application Number | 20200093400 15/748616 |
Document ID | / |
Family ID | 57943557 |
Filed Date | 2020-03-26 |
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United States Patent
Application |
20200093400 |
Kind Code |
A1 |
Hamner; Samuel Richard ; et
al. |
March 26, 2020 |
SYSTEMS, DEVICES, AND METHOD FOR THE TREATMENT OF
OSTEOARTHRITIS
Abstract
The present disclosure describes devices, methods and systems
for modifying or altering gait kinematics via sensory augmentation
and/or modifying muscle activation patterns via augmented motor
learning to slow the progression of and/or reduce the pain
associated with knee OA, particularly during gait (e.g., walking,
running, stair climbing, etc.). Sensors can be used to measure gait
parameters and characteristics and muscle activation patterns.
Stimulation can be provided to the individual in order to promote
learning new gait kinematics and muscle activation patterns.
Inventors: |
Hamner; Samuel Richard; (San
Francisco, CA) ; Rosenbluth; Kathryn H.; (San
Francisco, CA) ; Delp; Scott Lee; (Stanford, CA)
; Coleman; Daniel Lev; (San Francisco, CA) ;
Shull; Peter Bradley; (Atlanta, GA) ; Wong; Serena
HanYing; (Palo Alto, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Cala Health, Inc. |
Burlingame |
CA |
US |
|
|
Family ID: |
57943557 |
Appl. No.: |
15/748616 |
Filed: |
August 1, 2016 |
PCT Filed: |
August 1, 2016 |
PCT NO: |
PCT/US2016/045038 |
371 Date: |
January 29, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62199965 |
Jul 31, 2015 |
|
|
|
62276797 |
Jan 8, 2016 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 5/1038 20130101;
A61N 1/0484 20130101; A61B 5/6829 20130101; A61N 1/36031 20170801;
A61B 5/0488 20130101; A61B 5/112 20130101; A61B 5/4836 20130101;
A61B 5/6828 20130101; A61N 1/0456 20130101; A61N 1/36021 20130101;
A61N 1/36003 20130101; A61N 1/36034 20170801; A61B 5/1121 20130101;
A61B 5/6807 20130101; A61B 5/0205 20130101; A61N 1/0476 20130101;
A43B 3/0005 20130101; A43B 7/141 20130101; A61B 5/486 20130101 |
International
Class: |
A61B 5/11 20060101
A61B005/11; A61B 5/0488 20060101 A61B005/0488; A61B 5/00 20060101
A61B005/00; A61N 1/36 20060101 A61N001/36 |
Claims
1. (canceled)
2. (canceled)
3. (canceled)
4. (canceled)
5. (canceled)
6. (canceled)
7. (canceled)
8. (canceled)
9. (canceled)
10. (canceled)
11. (canceled)
12. (canceled)
13. (canceled)
14. (canceled)
15. (canceled)
16. (canceled)
17. (canceled)
18. (canceled)
19. (canceled)
20. (canceled)
21. (canceled)
22. (canceled)
23. (canceled)
24. A method for reducing knee pain associated with osteoarthritis
in an individual, the method comprising: measuring a gait
parameter; determining a deviation of the measured gait parameter
from a set range or value for the gait parameter; delivering a
sensory stimulation to the individual based on the determined
deviation of the measured gait parameter; and altering the
individual's gait kinematics such that the deviation of the
measured gait parameter is reduced in subsequent measurements of
the gait parameter.
25. The method of claim 24, wherein the gait parameter is selected
form the group consisting of foot angle, step width, knee angle,
and knee adduction moment.
26. The method of claim 24, wherein the set range or value is
predetermined.
27. The method of claim 24, wherein the sensory stimulation is
delivered in a fading feedback manner.
28. The method of claim 24, wherein the sensory stimulation is
electrical and is configured to not induce contraction of a
muscle.
29. The method of claim 28, wherein the electrical sensory
stimulation is configured to enhance motor plasticity.
30. The method of claim 24, further comprising: measuring an
activation of the gastrocnemius muscle; and delivering a second
sensory stimulation based on the activation of the gastrocnemius
muscle to inform the individual of the activation of the
gastrocnemius muscle.
31. The method of claim 30, further comprising: measuring an
activation of a soleus muscle; and delivering a third sensory
stimulation based on the activation of the soleus muscle to inform
the individual of the activation of the soleus muscle.
32. The method of claim 24, further comprising delivering a
stimulation configured to reduce an excitability of the
gastrocnemius muscle.
33. The method of claim 24, further comprising delivering a
stimulation configured to enhance an excitability or activate a
soleus muscle.
34. The method of claim 24, further comprising: measuring an
activation of the gastrocnemius muscle; measuring an activation of
a soleus muscle; delivering a second sensory stimulation based on
the activation of the gastrocnemius muscle to inform the individual
of the activation of the gastrocnemius muscle; delivering a third
sensory stimulation based on the activation of the soleus muscle to
inform the individual of the activation of the soleus muscle;
delivering a stimulation configured to reduce an excitability of
the gastrocnemius muscle; and delivering a stimulation configured
to enhance an excitability or activate a soleus muscle.
35. A method for reducing knee pain associated with osteoarthritis
in an individual, the method comprising: measuring a plurality of
gait parameters; determining a deviation of each of the measured
gait parameters from a set range or value for each of the gait
parameters; prioritizing the plurality of gait parameters based on
the determined deviations; identifying a high priority gait
parameter based on the step of prioritizing the plurality of gait
parameters; delivering a sensory stimulation to the individual
based on the high priority gait parameter; and altering the
individual's gait kinematics.
36. The method of claim 35, wherein the sensory stimulation is
delivered to a peripheral nerve in the leg.
37. The method of claim 35, wherein the sensory stimulation is
delivered to a sensory nerve in the leg.
38. A method for reducing knee pain associated with osteoarthritis
in an individual, the method comprising: measuring a plurality of
gait parameters; measuring activation of the gastrocnemius muscle;
determining a deviation of each of the measured gait parameters
from a set range or value for each of the gait parameters;
prioritizing the plurality of gait parameters based on the
determined deviations; identifying a high priority gait parameter
based on the step of prioritizing the plurality of gait parameters;
comparing the identified high priority gait parameter with the
measured activation of the gastrocnemius muscle; delivering a
sensory stimulation to the individual based on the comparison of
the high priority gait parameter with the measured activation of
the gastrocnemius muscle; and altering the individual's gait
kinematics or muscle pattern activation.
39. The system of claim 38, wherein the sensory stimulation
comprises a stimulation parameter selected from the group
consisting of: amplitude, frequency, pulse width, duration, and
waveform shape.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application No. 62/199,965, filed Jul. 31, 2015, and U.S.
Provisional Application No. 62/276,797, filed Jan. 8, 2016, each of
which is herein incorporated by reference in its entirety.
[0002] This application may be related to International Patent
Application No. PCT/US2014/012388, filed Jan. 21, 2014,
International Patent Application No. PCT/US2015/033809, filed Jun.
2, 2015, and PCT/US2016/037080, filed Jun. 10, 2016, each of which
is herein incorporated by reference in its entirety.
INCORPORATION BY REFERENCE
[0003] All publications and patent applications mentioned in this
specification are herein incorporated by reference to the same
extent as if each individual publication or patent application was
specifically and individually indicated to be incorporated by
reference.
FIELD
[0004] Embodiments of the invention relate to the treatment of
osteoarthritis, and more particularly to gait retraining and/or
modifying muscle activation patterns to treat knee pain associated
with osteoarthritis.
BACKGROUND
[0005] Osteoarthritis (OA) is the most common form of arthritis,
and both prevalence and incident rate increase with age. In the US,
for adults over 30, symptomatic knee OA affects about 6% of the
population. For ages 63-75, prevalence of knee OA increases to 11%
of women and 7% of men. Pain in the knee due to a disease such as
OA can have great functional impact and, especially among older
adults, often reduces ability in activities of daily living (ADL)
involving the legs, such as walking, transferring, and using the
bathroom. OA causes more disability in walking and climbing stairs
than any other disease and is the most common reason for total knee
and hip replacement.
[0006] General knee pain has an even greater healthcare and
societal impact. Two surveys assessing knee pain in older adults in
the UK both estimated an annual prevalence of 25% for knee pain in
older adults. In one of those studies, 15% of subjects in the
general population aged over 55 have had restricted activity
because of knee pain occurring on most days in one month during the
past year.
[0007] In knee osteoarthritis, the medial compartment of the knee
is affected ten times more often than the lateral compartment,
which is likely due to greater medial compartment loading during
gait to maintain knee joint stability. The first peak of the
external knee adduction moment (KAM) is a surrogate measure of
medial compartment loading, and has been correlated with pain and
presence, severity, and progression of medial compartment knee
osteoarthritis. Thus, treatments that reduce the KAM have the
potential for reducing pain and slowing progression of
osteoarthritis.
SUMMARY OF THE DISCLOSURE
[0008] The present invention relates to the treatment of knee pain
associated with osteoarthritis, and more particularly to gait
retraining and/or modifying muscle activation patterns to treat
osteoarthritis.
[0009] The recent advances in the miniaturization of sensors, power
sources, and stimulators, makes it possible to combine: (1) a
feedback or cuing system to monitor an individual's gait kinematics
and assist the individual in altering their gait by providing
real-time feedback to the individual (e.g., visual, auditory,
electrical, vibrational, etc.) without the need to visit a motion
analysis laboratory, (2) an electrical nerve stimulation device
that stimulates nerves around the knee from the skin surface to
reduce the pain associated with OA, and/or (3) an electrical muscle
stimulation device that alters muscle activation patterns based on
measured EMG signals. There are four major challenges for providing
effective feedback for gait modification; first, is to determine
who may benefit from a gait change; second, determine the gait
variable and target that will benefit an individual user ; third,
to accurately measure important gait variables and provide sensory
feedback and/or stimulation to promote a more biomechanically
effective walking pattern; and fourth, to effectively alter muscle
activation patterns to reduce knee loads that have a chronic,
long-term effect by initiating plastic adaptation of central neural
circuits and/or reflex pathways associated with gait.
[0010] There are also two major challenges for surface stimulation;
first, stimulating at the amplitudes required to effectively
stimulate these deep nerves may cause pain or discomfort due to the
stimulation of the cutaneous receptors; second, neuroanatomical
variability between individuals make it difficult to appropriately
position the stimulation electrodes from the surface. This system
for reduction of knee pain can increase the exercise tolerance of
an individual with knee OA, which could lead to increased knee
strength, improved joint stability, and further reduction in knee
pain.
[0011] In some embodiments, a system for reducing knee pain
associated with osteoarthritis in an individual is provided. The
system can include a wearable sensor for measuring a gait
parameter, and a therapy device in communication with the wearable
sensor. The therapy device can be configured to deliver a sensory
stimulation based on the measured gait parameter that is configured
to alter the individual's gait, where the sensory stimulation has a
stimulation parameter that is proportional to a deviation of the
measured gait parameter from a set range or value for the gait
parameter.
[0012] In some embodiments, the sensory stimulation is electrical
and is configured to not induce contraction of a muscle. In some
embodiments, the electrical sensory stimulation is configured to
enhance motor plasticity.
[0013] In some embodiments, the sensory stimulation is tactile or
auditory.
[0014] In some embodiments, the sensory stimulation is configured
to be provided in a fading feedback manner.
[0015] In some embodiments, the wearable sensor comprises an IMU or
a force sensor.
[0016] In some embodiments, the gait parameter is foot progression
angle, toe angle, ankle plantar flexion angle, step width, knee
flexion angle, knee adduction angle, or knee adduction moment, knee
flexion moment, or ankle plantar flexion moment, or any combination
of these gait parameters.
[0017] In some embodiments, the wearable sensor and/or therapy
device comprises a knee band, ankle band, leg band, sock, knee
brace, knee wrap, foot wrap, ankle brace, knee brace, ankle wrap,
shoe, shoe attachment, insole, compliant patch, pants, leg sleeve,
knee sleeve, or ankle sleeve.
[0018] In some embodiments, a system for reducing knee pain
associated with osteoarthritis in an individual is provided. The
system can include a wearable EMG sensor for measuring an
activation of a gastrocnemius muscle, and a therapy device in
communication with the wearable EMG sensor. The therapy device can
be configured to deliver a sensory stimulation based on the
measured activation of the gastrocnemius muscle, where the sensory
stimulation is configured to inform the individual of the
activation of the gastrocnemius muscle.
[0019] In some embodiments, the system further includes a second
EMG sensor for measuring an activation of a soleus muscle, where
the wearable therapy device is configured to deliver a second
sensory stimulation based on the measured activation of the soleus
muscle, where the second sensory stimulation is configured to
inform the individual of the activation of the soleus muscle.
[0020] In some embodiments, the system further includes a wearable
sensor for measuring a key gait event.
[0021] In some embodiments, the gait event is selected from the
group consisting of foot strike and toe off.
[0022] In some embodiments, the therapy device is configured to
deliver a stimulation configured to reduce the activation of the
gastrocnemius muscle.
[0023] In some embodiments, the therapy device is configured to
deliver the stimulation based on the measured gait parameter.
[0024] In some embodiments, the therapy device is configured to
deliver a stimulation configured to enhance the activation of a
soleus muscle.
[0025] In some embodiments, the therapy device is configured to
deliver the stimulation based on the measured gait parameter.
[0026] In some embodiments, a system for reducing knee pain
associated with osteoarthritis in an individual is provided. The
system can include a wearable sensor for measuring a gait
parameter, a wearable EMG sensor for measuring an activation of a
gastrocnemius muscle, and a therapy device in communication with
the wearable sensor and the wearable EMG sensor. The therapy device
can be configured to deliver a first sensory stimulation based on
the measured gait parameter that is configured to alter the
individual's gait and a second sensory stimulation based on the
measured activation of the gastrocnemius muscle, where the first
sensory stimulation has a stimulation parameter that is
proportional to a deviation of the measured gait parameter from a
set range or value for the gait parameter, and where the second
sensory stimulation is configured to inform the individual of the
activation of the gastrocnemius muscle.
[0027] In some embodiments, the therapy device is configured to
deliver a third stimulation configured to reduce the activation of
the gastrocnemius muscle.
[0028] In some embodiments, the therapy device is configured to
deliver a fourth stimulation configured to enhance the activation
of the soleus muscle.
[0029] In some embodiments, a system for reducing knee pain
associated with osteoarthritis in an individual is provided. The
system can include a wearable sensor for measuring a gait
parameter, a wearable EMG sensor for measuring an activation of a
soleus muscle, and a therapy device in communication with the
wearable sensor and the wearable EMG sensor. The therapy device can
be configured to deliver a first sensory stimulation based on the
measured gait parameter that is configured to alter the
individual's gait and a second sensory stimulation based on the
measured activation of the soleus muscle, where the first sensory
stimulation has a stimulation parameter that is proportional to a
deviation of the measured gait parameter from a set range or value
for the gait parameter, and where the second sensory stimulation is
configured to inform the individual of the activation of the soleus
muscle.
[0030] In some embodiments, the therapy device is configured to
deliver a third stimulation configured to enhance the activation of
the soleus muscle.
[0031] In some embodiments, the therapy device is configured to
deliver a fourth stimulation configured to reduce the activation of
the gastrocnemius muscle.
[0032] In some embodiments, the therapy device is wearable.
[0033] In some embodiments, the therapy device is a mobile phone or
smart watch.
[0034] In some embodiments, a method for reducing knee pain
associated with osteoarthritis in an individual is provided. The
method can include measuring a gait parameter; determining a
deviation of the measured gait parameter from a set range or value
for the gait parameter; delivering a sensory stimulation to the
individual based on the determined deviation of the measured gait
parameter; and altering the individual's gait kinematics such that
the deviation of the measured gait parameter is reduced in
subsequent measurements of the gait parameter.
[0035] In some embodiments, the gait parameter can be foot angle,
step width, knee angle, and knee adduction moment.
[0036] In some embodiments, the set range or value is
predetermined.
[0037] In some embodiments, the sensory stimulation is delivered in
a fading feedback manner.
[0038] In some embodiments, the sensory stimulation is electrical
and is configured to not induce contraction of a muscle.
[0039] In some embodiments, the electrical sensory stimulation is
configured to enhance motor plasticity.
[0040] In some embodiments, the method further includes measuring
an activation of the gastrocnemius muscle; and delivering a second
sensory stimulation based on the activation of the gastrocnemius
muscle to inform the individual of the activation of the
gastrocnemius muscle.
[0041] In some embodiments, the method further includes measuring
an activation of a soleus muscle; and delivering a third sensory
stimulation based on the activation of the soleus muscle to inform
the individual of the activation of the soleus muscle.
[0042] In some embodiments, the method further includes delivering
a stimulation configured to reduce an excitability of the
gastrocnemius muscle.
[0043] In some embodiments, the method further includes delivering
a stimulation configured to enhance an excitability or activate a
soleus muscle.
[0044] In some embodiments, the method further includes measuring
an activation of the gastrocnemius muscle; measuring an activation
of a soleus muscle; delivering a second sensory stimulation based
on the activation of the gastrocnemius muscle to inform the
individual of the activation of the gastrocnemius muscle;
delivering a third sensory stimulation based on the activation of
the soleus muscle to inform the individual of the activation of the
soleus muscle;
[0045] delivering a stimulation configured to reduce an
excitability of the gastrocnemius muscle; and delivering a
stimulation configured to enhance an excitability or activate a
soleus muscle.
[0046] In some embodiments, a method for reducing knee pain
associated with osteoarthritis in an individual is provided. The
method can include measuring a plurality of gait parameters;
[0047] determining a deviation of each of the measured gait
parameters from a set range or value for each of the gait
parameters; prioritizing the plurality of gait parameters based on
the determined deviations; identifying a high priority gait
parameter based on the step of prioritizing the plurality of gait
parameters; delivering a sensory stimulation to the individual
based on the high priority gait parameter; and altering the
individual's gait kinematics.
[0048] In some embodiments, the sensory stimulation is delivered to
a peripheral nerve in the leg.
[0049] In some embodiments, the sensory stimulation is delivered to
a sensory nerve in the leg.
[0050] In some embodiments, a method for reducing knee pain
associated with osteoarthritis in an individual is provided. The
method can include measuring a plurality of gait parameters;
[0051] measuring activation of the gastrocnemius muscle;
determining a deviation of each of the measured gait parameters
from a set range or value for each of the gait parameters;
prioritizing the plurality of gait parameters based on the
determined deviations; identifying a high priority gait parameter
based on the step of prioritizing the plurality of gait parameters;
comparing the identified high priority gait parameter with the
measured activation of the gastrocnemius muscle;
[0052] delivering a sensory stimulation to the individual based on
the comparison of the high priority gait parameter with the
measured activation of the gastrocnemius muscle; and altering the
individual's gait kinematics or muscle pattern activation.
[0053] In some embodiments, the stimulation parameter is amplitude,
frequency, pulse width, duration, or waveform shape.
BRIEF DESCRIPTION OF THE DRAWINGS
[0054] The novel features of the invention are set forth with
particularity in the claims that follow. A better understanding of
the features and advantages of the present invention will be
obtained by reference to the following detailed description that
sets forth illustrative embodiments, in which the principles of the
invention are utilized, and the accompanying drawings of which:
[0055] FIG. 1 is a schematic diagram illustrating some embodiments
of a system to modify human gait kinematics and/or modify muscle
activation patterns.
[0056] FIGS. 2A-2F illustrates an embodiment of a wearable system
and device.
[0057] FIG. 3 illustrates another embodiment of a wearable system
and device.
[0058] FIG. 4 illustrates an embodiment of a system and device that
can be embedded or integrated into a shoe.
[0059] FIG. 5 illustrates an embodiment of an electrode array.
[0060] FIG. 6 illustrates another embodiment of a system and device
that can be embedded or integrated into a shoe.
[0061] FIG. 7 illustrates an embodiment of the system and device
with a dispensable conductive gel that can include a
medication.
[0062] FIG. 8 illustrates another embodiment of an electrode array
that can be made from a crossweave fabric.
[0063] FIG. 9 illustrates an embodiment of a flexible device that
can be affixed to a body part.
[0064] FIG. 10 illustrates another embodiment of a flexible device
that has a flexible substrate that conforms to the body.
[0065] FIGS. 11A-11C illustrate various embodiments of the system
device being worn on various body parts.
[0066] FIG. 11D illustrates an embodiment of a patch device.
[0067] FIG. 12 illustrates an embodiment of a system and device
with an array of effectors.
[0068] FIG. 13 illustrates a flowchart of an embodiment of a method
to determine various gait parameters.
[0069] FIGS. 14A-14D illustrate various techniques for determining
various gait parameters.
[0070] FIG. 15 illustrates various embodiments of a device inserted
into the sole of a shoe.
[0071] FIG. 16 illustrates the mechanics of the foot during
gait.
[0072] FIGS. 17A and 17B illustrate embodiments of responsive
feedback and fading feedback.
[0073] FIG. 18 illustrates an embodiment of the system and device
where the therapy unit and sensor unit are incorporated into a
single wearable device.
[0074] FIG. 19 illustrates a way to determine foot orientation from
a foot pressure map.
[0075] FIG. 20 illustrates another embodiment of a system and
device that has been integrated into a shoe.
[0076] FIG. 21 illustrates knee load during walking.
[0077] FIGS. 22A-22C illustrates various muscles in the leg that
are used during walking that can contribute to knee load.
[0078] FIGS. 23A and 23B illustrate the reduction in knee load from
applying embodiments of the therapy described herein.
[0079] FIGS. 24A-24H illustrate various locations on the body that
can be target by the systems and devices described herein.
DETAILED DESCRIPTION
[0080] "Electrical stimulation" refers to the application of
electrical signals to the soft-tissue and nerves of the targeted
area. Applying a "vibrotactile stimulation" refers to the
application of a vibrational load to the soft-tissue and nerves and
mechanoreceptors of the targeted area.
[0081] The systems, devices, and methods of this disclosure each
have several innovative aspects, no single one of which is
necessarily solely responsible for the desirable attributes
disclosed herein. The present disclosure describes devices, methods
and systems for (1) modifying or altering gait kinematics (or
motion) via sensory augmentation and/or (2) modifying muscle
activation patterns via augmented motor learning to slow the
progression of and/or reduce the pain associated with knee OA,
particularly during gait (e.g., walking, running, stair climbing,
etc.). In some embodiments, peripheral nerve stimulation is used in
conjunction with monitoring gait kinetics and kinematics and/or
muscle activations, and providing real-time feedback to the
individual. In some embodiments, a device is provided. Individuals
with OA may have reduced proprioception and may therefore benefit
from sensory augmentation therapies.
[0082] Additionally, repeated practice or exercise of a movement
has been shown to elicit a plastic effect on in the brain,
specifically in motor cortex. Repeated practice or exercise can be
timed with electrical stimulation of specific nerves, muscles,
reflex pathways, and/or motor cortex to enhance or accelerate the
plastic effect. Thus, having an individual modify their gait
kinematics in a specific, repeated practice can have lasting effect
on gait patterns by retraining existing neural pathways in motor
cortex or other parts of the central nervous system. To utilize
this plastic change for the reduction of pain due to OA, a device
will need to be sufficiently accurate and provide sensory feedback
about specific gait variables to the individual at each step during
the gait motion. This type of portable, wearable gait retraining
system has not been possible in the past due to challenges in size,
cost, and accuracy of sensors, especially portable, wireless
sensors, power sources, and processors.
[0083] Stimulation applied to nerves and/or muscles can affect gait
in multiple ways:
[0084] First, by direct muscle stimulation, when electrical
stimulation is applied above muscle contraction thresholds and
targets efferent nerves that innervate muscle or target muscle
directly, this causes the muscle to contract and generate force to
affect movement, similar to functional electrical stimulation
(FES).
[0085] Second, by muscle re-patterning, stimulation is applied to
afferent or sensory nerves that innervate muscle below muscle
contraction threshold but above stimulation threshold of nerves;
neuronal activity propagates to reflex circuits, like H-reflex, as
well as back to the brain, especially motor cortex, and the central
nervous system, causing plastic changes in the excitability of
neural circuits and/or the muscles that drive regular gait
patterns. Muscle re-patterning thus trains the wearer to transfer
activation, and force, from one muscle (e.g., gastrocnemius) to
another muscle (e.g., soleus) to unload the medial compartment
during gait.
[0086] Third, by sensory augmentation, stimulation signals are
applied to afferent or sensory nerves to lead a person to correct
the motion causing pain. In OA, there is a delay between when a
person performs the motions that overload the knee and experiences
the resulting pain. Sensory augmentation uses sensory feedback to
passively provide feedback to the central nervous system that
causes someone to correct their motion. For example, in knee pain
associated with OA, affectors may be positioned on the bottom or
sides of the foot along the femoral and tibial distributions to
provide sensory feedback to toe-in or toe-out. This may be less
mentally taxing than cuing, and also more efficiently entrain
sensory-motor circuits to produce motor plasticity in limb cortical
areas. The electrical stimulation of the sensory nerves may also
lead to stimulation of limb cortical areas of the brain that
enhance motor plasticity and help an individual learn a new gait
more quickly.
[0087] The device and system can use one or any combination of the
above concepts to modify a person's gait to reduce pain and
progression of OA.
Systems and Devices for Treating OA
[0088] Error! Reference source not found. is a conceptual diagram
illustrating some embodiments of a system 10 to modify human gait
kinematics and/or modify muscle activation patterns. The System 10
includes a Housing 20, either flexible or rigid, one or more
Affectors 30, one or more Controls 40 in electrical communication
with the Affector 30, and one or more Power Sources 50. The
Affector 30 can be, for example, an electrical nerve stimulator,
vibrotactile stimulator, an implanted electrical nerve stimulator,
and/or any device capable of delivering a nerve affecting signal.
The Housing 20 can, in some embodiments, include an Interface 60.
The Interface facilitates the coupling of the Affector to the
subject. For example, the Interface can provide a physical,
electrical, and/or chemical connection or point of contact to the
subject. Further aspects and embodiments of the present invention
are set forth herein. These and other aspects and embodiments of
the invention are described in greater detail below, with reference
to the drawing figures.
[0089] In some embodiments, the device is a wearable device with an
electrically conductive skin interface that excites the underlying
nerves from a transcutaneous surface stimulator. The device may be
sized for a range of user sizes with stimulation electrodes
positioned to target the appropriate nerves, as in the device
described by International Patent Application No.
PCT/US2014/012388, International Patent Application No.
PCT/US2015/033809, and
[0090] International Patent Application No. PCT/US2016/037080.
[0091] In another embodiment, the device and system is a wearable
device with an electrically conductive skin interface that excites
the underlying nerves from a transcutaneous surface stimulator and
has embedded motion sensors (e.g., accelerometers, gyroscopes,
magnetometer, bend sensors) and/or force sensors (e.g., strain
sensors or pressure insoles) that measure the wearer's gait
kinematics (e.g., toe-in angle) and/or kinetics (e.g., ground
reaction force or knee joint loads) and store the data to a memory
unit either on the device or in a separate unit that communicates
via a wired or wireless connection.
[0092] In one embodiment as illustrated in FIGS. 2A-2E, the system
and device is a wearable unit 200 that includes a wearable strap or
band 202 and housing 204 for holding electronics 206. The
electronics 206, shown in FIG. 2E can include one or more inertial
measurement units (IMU) 208 (e.g., motion sensors such as
accelerometers, gyroscopes, magnetometers, bend sensors), force
sensors (e.g., strain sensors), muscle and/or nerve activity
sensors (e.g., electrodes to measure EMG or microneurography) that
communicate with a device control unit that processes measurement
data to calculate one or more key gait parameters, such as gait
kinematics (e.g., foot-progression angle, knee angle, step width
etc.), kinetics (e.g., ground reaction force), muscle activation,
or conduction of pain signals to the central nervous system. The
electronics 206 can also include a processor 210 and memory 212 for
storing instructions, that when executed by the processor, perform
the algorithms, calculations, and steps described herein. The
memory 212 can also store data gathered by the sensors and store
information regarding the use of the device, including how and when
the device delivered stimulations or cues to the individual, for
example. The electronics 206 can also include a power supply 214
and power regulator 216 to power the various electronic components,
and a communications module 218, which can be wireless, to
communicate with other sensors, wearable devices, or computing
devices such as mobile phones, tablets, or computers.
[0093] In another preferred embodiment, the device also houses one
or more affectors to provide sensory feedback, which could be in
the form of electrical stimulation through electrodes, vibration
(e.g., vibration motor), auditory (e.g., speakers or headphones),
tactile (e.g., skin stretch), or visual (e.g., LEDs on device,
smartphone screen, or glasses).
[0094] In some embodiments as shown in FIG. 2F, the device and
system includes one or more wearable devices 200 with an
electrically conductive skin interface for transcutaneous nerve
stimulation, embedded measurement sensors, and sensory feedback
units (i.e., cuing, muscle repatterning, and/or sensory
augmentation) that notify the wearer of deviations in gait
variables. In this embodiment, the device includes two separate
units that communicate by wired connection or wireless
communication (e.g., low-energy Bluetooth). Gait deviations can be
calculated with data from embedded motion sensors and the device
control unit. Sensory feedback to the wearer could be in the form
of vibrotactile sensation (e.g., vibration motors), auditory
sensation (e.g., speakers), tactile sensation (e.g., skin stretch
or band tightening), electrical stimulation of peripheral nerves
such as the tibial nerve or other sensory nerves, or other standard
forms of haptic feedback. The feedback system could also notify the
wearer of key events based on analysis of biological measures,
including, but not limited to, prediction of pain level increase.
The system, which may include cuing, could also notify the wearer
of other predetermined events or reminders set by the wearer. An
advantage of the system is that information can be communicated to
the wearer real-time during activities, such as walking, running,
or stair climbing. Instead of or in addition, the device can
provide stimulation or modulate the stimulation to retrain gait
such that the feedback is provided less frequently or at a
decreased intensity level until it is no longer needed, referred to
hereafter as fading feedback, as further described herein with
respect to stimulation that promotes learning, for example.
[0095] In some embodiments, the sensor(s) and affector(s) may be
combined into a single device, or they may be separate devices,
wherein they are capable of rapid wireless or wired communication,
as illustrated in FIG. 2F.
[0096] In some embodiments, the wearable unit houses an electrical
stimulation unit that is connected to the wearer's skin through an
electrically conductive skin interface to provide transcutaneous
stimulation. In a further extension, the stimulation unit may have
a logic controller that adjusts stimulation parameters (e.g.,
stimulation amplitude, frequency, waveform, etc.) based on sensor
measures and/or calculated gait parameters.
[0097] In some embodiments as shown in FIG. 3, the wearable device
300 includes a linear array of stimulation affectors (e.g.,
electrical or vibrotactile) 302 that are circumferentially
distributed in a band that is intended to be worn around the leg,
such as the calf, the knee, the ankle, or the thigh. The
stimulation affectors are driven in a timed pattern to give the
wearer a sense of direction to alter their gait. For example, the
affectors could be driven in a clockwise pattern to inform the
individual to toe-out while walking, and the motor could be driven
in a counter-clockwise pattern to indicate toe-in gait.
[0098] In some embodiments as shown in FIG. 4, the system can
include a measurement unit 400 and a cuing unit or stimulation unit
402 that are embedded into an insole 404 that is inserted into the
individual's shoe. The insole can have pressure sensors, such as
strain or piezoelectric sensors, to measure ground reaction
pressure or force of the individual, and could have accelerometers,
gyroscopes, and magnetometers to measure the position and
orientation of the individual's lower limb. The insole can also
have an array of stimulation affectors to provide feedback, which
may include cuing, to the individual. Affectors could be oriented
in two arrays longitudinally on the medial and lateral side of the
foot to indicate direction to the individual; or motors could be
oriented transversely across the ball of the foot to indicate
direction. In some embodiments, the system can have electrodes for
providing electrical stimulation, vibration motors for vibrotactile
stimulation, or speaker(s) for providing auditory stimulation. The
system can also include a battery 406 and electronics as described
herein.
[0099] In some embodiments, the wearable unit with measurement
sensors (e.g. FIG. 2B-D) could be embedded into the sole of a shoe,
as shown in FIG. 15. Ideally, measurement sensors that incorporate
rigid components (e.g., circuit board or battery) are embedded
under the heel, as this location undergoes less strain due to
bending of the foot and shoe during gait, as illustrated in FIG.
16.
[0100] In some embodiments, the wearable device can use a plurality
of sensors to collect, store, and analyze biological measures about
the wearer including, but not limited to, motion (e.g.,
accelerometers, gyroscopes, magnetometer, bend sensors), ground
reaction force or foot pressure (e.g., force sensors or pressure
insoles), muscle activity (e.g., EMG), cardiovascular measures
(e.g., heart rate, heart rate variability), skin conductance (e.g.,
skin conductance response, galvanic skin response), respiratory
rate, skin temperature, and sleep state (e.g., awake, light sleep,
deep sleep, REM). Using standard statistical analysis techniques,
such as a logistical regression or Naive Bayes classifier, these
biological measures can be analyzed to assess a person's state,
such as activity, such as sedentary versus active, and muscle
usage, which in turn, can serve as a predictor for increases in
pain levels.
[0101] In some embodiments, the measurement unit could employ
accelerometers, gyroscopes, and/or a magnetometer attached to the
individual's foot or ankle or shoe or sock to measure foot
progression angle, which can be used to provide feedback to the
individual about toe-in/toe-out of their gait. For example,
measurement of progression angle can be calculated by taking the
difference between foot orientation measured with gyroscopes and a
heading direction determined from the magnetometer.
[0102] In some embodiments, the measurement unit could employ two
sensors or two sets of sensors that measure step width (i.e., the
lateral distance between steps) of the individual's gait. Step
width could be measured by calculating position of each foot during
a step from accelerometers, using a magnetometer to perform a dead
reckoning correction of drift of the accelerometer. Step width
could also be measured using a sonar or radar system where there is
a unit attached to one foot sending and receiving a sonar signal
and another unit attached to the opposite foot that reflects the
signal; distance between the feet could be estimated as the feet
pass by each other during the gait cycle.
[0103] In some embodiments, the wearable device can communicate
with an external computer or device (e.g., tablet, smartphone,
smartwatch, or custom base station) to transmit, store, and process
data. Communication between the wearable device and external device
can be a direct, physical connection, or with a wireless
communication connection such as Bluetooth or GSM or cellular.
[0104] In some embodiments as shown in FIG. 5, the device contains
a 2D or 3D array 500 of electrodes 502 such that the stimulation
may be targeted. The elements of the array, the electrodes 502, may
be individually addressable such that the location of stimulation
can be adjusted on-the-fly or for each session, such as electronic
referencing. Alternatively, the elements may be configured for an
individual user, such as a mechanical configuration in which the
electrode connections are cut or spliced to customize the
device.
[0105] In some embodiments, the system communicates with an
external, portable computational device, such as a smartphone via
an app, or other mobile digital interaction. The device may be used
to track information of relevant events either user entered or
automatically captured from biological sensors, such as the time
since the last knee pain, activity level, or joint load. In a
further extension of this embodiment, this information may be used
to close the loop to adjust stimulation parameters (waveforms,
amplitude, on/off) or suggest user behaviors.
[0106] In some embodiments, the system could centrally store
biological measures from multiple wearers on a server system (e.g.,
the cloud), along with other relevant demographic data about each
user, including age, weight, height, gender, ethnicity, etc. Data
collected from multiple wearers is analyzed using standard
statistical techniques, such as a logistic regression or Naive
Bayes classifier (or other classifiers), to improve prediction of
pain level increases by determining correlations between biological
measures, activity level, and other recorded events. These
correlations are used to set parameters of the stimulation waveform
applied by the stimulation unit, determine best time to apply
stimulation therapy, and/or adapt the stimulation waveform applied
by the stimulation unit in real time. In addition, these
correlations can be used to provide recommendations to the wearer
about when to perform therapy or other techniques to reduce pain.
In a further extension of this embodiment, the server system can
also download and analyze information from the scientific
literature to set parameters that adjust stimulation and/or
recommendations to the wearer.
[0107] In some embodiments, the form of the device could be a knee
band, ankle band, sock, knee brace, knee wrap, ankle brace, ankle
wrap, shoe or shoe attachment, insole, compliant patch, pants, or a
leg sleeve. For example, FIG. 6 shows an embodiment of the device
which can include a stimulation and/or sensor unit that can be
integrated and/or embedded into a shoe 600. For example, the
electronic components 602 can be placed, for example, between the
sole 604 and the upper portion 606 of the shoe. Other placement
locations on the shoe include the heel or back portion of the shoe,
the tongue of the shoe, or the upper portion of the shoe.
[0108] In some embodiments, the wearable device can have a
processing unit that collects, stores, processes, and analyzes the
biological measures, along with other data input by the wearer,
such as logging activities or inputting body weight and other user
characteristics.
[0109] In some embodiments, the wearable device can have a GPS or
similar device to track the location and assess activity of the
wearer. GPS measures can be combined with mapping or location
systems to determine context of the wearer's activity (e.g., gym
versus office) or determine changes in elevation during specific
activities, such as running or stair climbing.
[0110] In some embodiments, the wearable device can track
parameters about stimulation provided by the stimulation unit,
including time of stimulation, duration of the stimulation session,
and power used by the stimulation unit. This data can be stored on
memory in the wearable device, processed by the wearable device,
and/or transmitted to an external computing device.
[0111] In some embodiments, the stimulation unit can use switches
or electrical sensor to detect connection of electrodes: to ensure
proper and unique electrodes are being installed (i.e., not using a
different or incorrect type of electrode) communicating a unique
code, for example via RFID; to regulate the number of uses for each
electrode to prevent over use; and to prevent the usage of the
device without an electrode to prevent small shock.
[0112] In some embodiments, the system may include features to
increase skin comfort. One solution is to use a high frequency
carrier (kHz or greater) wave over the low frequency beats (10 to
200 Hz), or to position electrodes such that the interaction of two
waveforms combines to produce a low frequency beat.
[0113] In some embodiments as shown in FIG. 7, lidocaine or a
similar pain reducing compound (e.g., other analgesics or
anesthetics) may be incorporated into an electrode hydrogel 700 to
numb the skin surface 702 or desensitize the surface receptors to
increase skin comfort. Alternatively, this chemical compound gel
could be pushed out from the device similar to how deodorant is
snap-clicked out from a deodorant stick, by using a screw mechanism
with a plunger 704 that pushes the gel out of the housing 706
through channels 708 in the bottom of the housing that contacts the
skin, for example. Another approach is to hypopolarize by initially
hyperpolarizing using an excitatory agent like alpha hydroxyl
sanshool.
[0114] In some embodiments, to improve skin comfort, the skin may
be cooled by attaching an outer sleeve containing a cold material,
such as a gel, or circulating a cold fluid in pipes housed in the
sleeve.
[0115] In some embodiments, to improve skin comfort or improve
perception of feedback, the wearable device could house a vibration
motor to apply a vibrational stimulation simultaneously with
electrical stimulation.
[0116] In some embodiments, the wearable device has the form of a
sock, which is near-field powered by coupling between electronics
and coils in the sole of a shoe and a coil in the sock.
[0117] In some embodiments as shown in FIG. 8, the wearable device
is in the form of a sock, sleeve or other garment that contains an
electrode array that can be formed from a crossweave fabric 800 in
which a strip along the top or side of the fabric is referenced
such that the electrode 802 is positioned at the intersection of
the conductive threads, which can have electrical connectors 804
that can be put in electrical communication with a power
source.
[0118] In some embodiments as shown in FIG. 9, the device is a
flexible housing or patch 900 with an adhesive that adheres
directly to the wearer's skin. This embodiment has a device with
flexible circuitry 902, and a slim, light-weight design to not be
cumbersome when worn on the body. Possible locations for the sticky
patch could include the foot (either dorsal or plantar side) or on
the shank/tibia close to nerves associated with reduction of knee
pain, such as the saphenous nerve or tibial nerve. The flexible
housing or patch 900 encloses or has a circuit board 904, such as
the circuit board described in FIG. 2E and elsewhere, and one or
more affectors 906. The affectors are in electrical communication
with the circuit board via flexible circuits. The shape of the
housing can improve repeatability of positioning the device, for
example the widest portion of the housing can be aligned with the
long axis of the foot. Additionally the t-shape illustrated allows
the affectors to conform around the foot shape and provide physical
separation of the affectors to allow distinct perception by the
wearer.
[0119] In some embodiments, the housing could have a specific
shape, for example a t-shape as illustrated in FIG. 9, to allow for
easier alignment of the device on the foot, which improves
estimation of foot orientation.
[0120] In some embodiments, the affectors are disposed in the
flexible housing and attached to an electronics board with a
flexible circuits FIG. 9, to allow for a flexible housing that
conforms to the shape of the body part.
[0121] In some embodiments as shown in FIG. 10, the electronics
board 1000 with various electronic components 1002 may be rigid and
mount to a more flexible or elastic substrate material 1002, such
as silicone or rubber, to allow the device to be worn on the body
1006 and conform to different body part shapes.
[0122] In other embodiments as shown in FIGS. 11A-11D, the device
or system can have many form factors and can include any
combination of the form factors described herein. For example, the
device could be a fabric garment woven with conductive fabric.
Fabric garments can contain electronic fabric with
stretch-sensitive fibers for measuring limb position and
displacement, and foot pressure, in addition to conductive pathways
for electrical stimulation and embedded accelerometers. For
example, as shown in FIG. 11A, the device can include a sleeve 1100
wrapped around an extremity, such as a sleeve wrapped around the
leg just below the knee. The sleeve can slide on over the leg, or
wrap and fasten around the leg with Velcro, snaps, or other common
fasteners. FIG. 11B illustrates a flexible device that adheres to
the skin like a patch 1102 or bandage, similar to FIGS. 9 and 10,
where the device is adhered to the posterior side of the ankle,
just above the Achilles' tendon. FIG. 11C illustrates a sock-like
fabric garment 1104 worn on the foot. FIG. 11D illustrates a
flexible patch 1106 with two electrodes 1108 to target a single
nerve. The flexible patch can be coated with a conductive and
adhesive hydrogel. The patch can be made of a flexible material,
like silicone, to conform to body (e.g., behind knee). The center
housing 1110 contains stimulation electronics, sensors, processor,
and power source, for example. The housing 1110 may also include a
basic user interface 1112 (i.e., one or more buttons) to control
stimulation level and/or display information to user. The patch may
or may not communicate wirelessly with an external device
[0123] In some embodiments the device houses a single affector or a
plurality of affectors. Specifically, a single affector would
provide feedback to the wearer about a single task or direction
(e.g., turn left), while two affectors could provide feedback about
two tasks or directions (e.g., turn left or turn right). With two
affectors, the affectors need to have enough physical separation to
have distinct perception by the wearer. The specific minimum
separation distance depends on the specific part of the body where
the affectors are applied, the density of sensory receptors, and
the type of stimulation. For vibration, a minimum distance can be
as low as 15 mm, but preferably between 35-50 mm. Affectors 1200
can also be ordered in an array, for example linear or circular,
and activated in specific sequences to convey directionality, as
illustrated in FIG. 12.
[0124] In some embodiments, the affectors can be stimulated using
different specific waveforms to convey a plurality of tasks or
actions to the wearer. Waveform parameters that can be varied
include amplitude, frequency, pulse width, and duration. Patterns
of stimulation bursts can also be used as unique signals. Changes
in waveforms need to be varied enough for the wearer to perceive
unique sensory feedback signals.
[0125] In some embodiments, the device could contain an insole or
woven fabric under the foot that can measure force or pressure
between the foot and the ground. As shown in FIG. 19, a method to
calibrate the orientation 1900 of the foot relative to the wearer's
body can include calculating a foot pressure map 1902 from the
sensor data after the wearer is instructed to stand in a predefined
pose. Key landmarks 1904 from the pressure map 1902 are then
identified to estimate the orientation of the foot.
[0126] In some embodiments, the wearable unit is in communication,
either wired or wirelessly, with a separate stimulation unit that
provides transcutaneous stimulation to a location different from
that of the wearable unit.
[0127] In some embodiments as shown in FIG. 20, the wearable device
2000 has a portable, rechargeable power source, which is near-field
powered by coupling between electronics and coils 2002 in the
device (i.e., wireless charging) with a wireless charger 2004.
[0128] In some embodiments, the wearable unit stores data to a
memory unit either on the device or in a separate unit (e.g.,
tablet, smartphone, smartwatch, or custom base station) that
communicates through a wired connection or wirelessly (e.g., low
energy Bluetooth or GSM).
[0129] In some embodiments, the wearable device can have a
processing unit that collects, stores, processes, and analyzes the
biological measures, along with other data input by the wearer. In
some embodiments, some of the processing of the data can be
performed on an external computing device or on the cloud.
[0130] In some embodiments, the electrodes for transcutaneous
electrical stimulation are dry electrodes made from a conductive
materials, such as metallic fabrics or conductive silicone.
[0131] The systems, devices, and methods described herein allow the
detection or determination of gait variables that are difficult for
an individual to detect or sense, such as the adduction moment of
the knee, and then provide the individual with sensory stimulation
as a proxy for that gait variable, allowing the individual to
modify aspects of their motion that are difficult to sense.
[0132] Although feedback stimulation can be provided on the leg,
ankle, knee, and foot, location of the stimulation can also be
positioned on different locations of the body, for example, audio
or vibratory stimulation from an individual's smartphone or a
smartwatch worn on the wrist.
[0133] In addition to the locations of sensors and affectors
described elsewhere in this application, FIGS. 24A-24H illustrate
other locations where sensors and/or affectors can be positioned.
For example, FIG. 24A illustrates positioning a stimulator 2400 on
the upper leg and behind the knee using a knee brace 2402 or band
or sleeve. FIG. 24B illustrates shorts 2404 with fiber optic
sensors 2406. The fiber optic sensor extends from the persons trunk
to the knee or joint of interest. The fiber uses three components
of strain and twist in order to calculate the relative orientation
of the joint of interest based on the detected orientation of the
fiber. FIGS. 24C and 24D illustrate placing a sensor 2408 such as
an IMU at the back of the heel or on the ankle to determine foot
angle. The back of the foot or ankle is more stable than the top or
toe portion of the foot. FIG. 24E illustrates placing a stimulator
2400 on the lower leg and behind the knee using a knee brace 2402
or band or sleeve. FIG. 24F illustrates placing a stimulator 2410
on the ankle using an ankle strap 2412. FIG. 24G illustrates the
locations to stimulate the superficial peroneal nerve 2413 and the
saphenous nerve 2414 on the leg.
[0134] FIG. 24H illustrates the locations to stimulate the common
peroneal nerve 2416 and the tibial nerve 2418 on the leg.
Method of Altering Gait Kinematics via Sensory Augmentation
Therapy
[0135] For knee OA, the first peak of the external knee adduction
moment (KAM) is often used as a surrogate measure of medial
compartment loading and has been correlated with pain and the
presence, severity, and progression of medial compartment knee OA.
Multiple studies have also shown that individuals with OA can alter
their gait kinematics to reduce the first peak of the KAM and
reduce knee pain. For example, studies have shown that teaching
individuals to walk with a toe-out gait or with a greater step
width can reduce the peak of the KAM and/or reduce knee loads.
However, these studies were performed in a controlled motion
analysis laboratory with expensive motion tracking equipment that
requires individuals with OA to return to the lab for training to
learn the gait modifications that reduced their KAM. Therefore, in
some embodiments, the key gait parameter(s) may be foot progression
angle, step width, knee angle or a measure of KAM itself, for
example. The systems and devices described herein can be used to
determine the key gait parameters.
[0136] In some embodiments, the key gait parameter may be foot
progression angle, which is defined as the angle between the foot
vector and the heading vector (line of walking progression). The
foot progression angle is determined in six steps as shown in FIG.
13. Orientation 1300 is estimated via the gradient descent
algorithm, trajectory 1302 is estimated via strapdown integration,
and stance phase identification 1304 is used with zero-velocity
detection to correct velocity estimation drifts. The heading vector
1306 and foot vector 1308 are computed based on results of
trajectory and orientation estimation, respectively, and the foot
progression angle 1310 is the difference between these vectors in
the horizontal plane.
[0137] As shown in FIG. 14A, sensor orientation is estimated with
respect to the earth frame by integrating angular velocity, from a
gyroscope for example, and then applying gradient descent
correction with accelerometer and magnetometer data to get
drift-reduced orientation estimation.
[0138] As shown in FIG. 14B, the foot trajectory is computed
through double integration of the acceleration in the earth frame
and is corrected via the zero-velocity assumption during stance.
Zero-velocity estimation based on acceleration and gyroscope
information to help estimate the stance period and implement a
state-machine based approach for improved identification accuracy.
In addition, heel strike events are detected from the accelerometer
and gyroscope and the stance phase duration is approximated as 60%
of the stride time.
[0139] As shown in FIG. 14C, the foot vector is estimated as the
common vector fixed in an IMU-sensor frame. In other words, the
foot vector is fixed with respect to the sensor frame S, then is
transformed into the earth frame using the corrected orientation
estimated from the previous step. Each subject performs
dorsiflexion and plantarflexion motion of the ankle to calibrate
the device.
[0140] As shown in FIG. 14D, the heading vector estimates the
direction of forward movement by calculating a foot trajectory at
each heel strike by subtracting the current foot trajectory from
the foot trajectory at the previous heel strike. To improve heading
vector estimation, a complementary filter parameter can also be
applied to the foot trajectory at each stride. Finally, the foot
progression angle (FPA) is computed as the difference between the
heading vector and foot vector integrated over the stance phase of
each step. In other words, the foot progression angle is computed
as the average angle between the foot vector and heading vector
during stance. The foot vector is computed at each time step, while
the heading vector is estimated at each stride after heel strike.
At each time step, an angle is defined between the foot vector and
the heading vector projected onto horizontal plane parallel with
the ground, and the foot progression angle for each step is the
average of this angle during stance.
[0141] The above method was implemented with a wearable sensor and
compared to measurements from an optical motion capture system on
13 subjects. The device and method exhibited accuracy similar with
the motion capture system.
[0142] Step width can also be determined using the procedure
described above, using a subset of the parameters and calculations
described above.
[0143] KAM can be measured by measuring the ground reaction force
and determining the position of the parts of leg. For example, the
ground reaction force can be estimated or determined based on the
body mass of the individual or by direct measurement using sensors
in the shoe or bottom of the foot. The position of parts of the leg
can be determined by placing and IMU or accelerometer on the upper
leg and the lower leg and performing a double integration on the
acceleration data to determine position.
[0144] In some embodiments as shown in FIG. 17A, the device
provides feedback to the wearer when the calculated gait parameter
deviates outside of a specified ideal range from step-to-step
during gait in two different directions. Providing feedback in this
manner can be accomplished with either two affectors or two
distinct waveform patterns delivered by a single affector such that
the wearer can discern between two different stimulations or cues.
As shown, the magnitude of the feedback provided to the individual
is related to or proportional to the magnitude of the deviation of
the gait parameter from the ideal range.
[0145] In an extension of the previous embodiment as shown in FIG.
17B, the device provides feedback to the wearer when the calculated
parameter deviates outside of the ideal range in one specific
direction. This method for feedback could be useful when changes in
gait parameter in only a single direction (e.g., toe-in versus
toe-out) affect knee pain, and only requires a single affector
delivering a single waveform pattern.
[0146] In some embodiments, the feedback can be stimulation to
sensory nerves during gait to enhance sensory feedback of knee
pain, or of a key variable associated with knee pain, such as foot
angle, step width, knee angle, KAM, etc. In some embodiments, the
sensory nerves are peripheral nerves located on the leg. In some
embodiments, the stimulation may be subsensory, or may be a
combination of sensory and subsensory stimulation, such as
providing subthreshold electrical stimulation along with an audible
or vibratory stimulation. In other embodiments, all the stimulation
are above sensory threshold.
[0147] In another embodiment, the device is in communication with
the affector(s) to apply stimulation to a predetermined or
predetermined set or subset of nerves that provide sensory feedback
to the central nervous system about pain and a sensor that measures
activity of sensory nerves that cause pain (e.g., microneurography)
and/or to block or modulate pain signals being sent to the brain.
The affector(s) would apply stimulation that is above a threshold
to activate sensory nerves, but below a threshold to contract
muscle. Activating more sensory nerves associated with knee pain
would provide augmented feedback to the central nervous system,
which would elicit plastic changes. The affector(s) may be
positioned on the femoral nerve to provide both sensory feedback
and modulate pain signals, as the femoral nerve is a common site
used for post-surgical nerve block. The affector(s) may also be
positioned on the saphenous nerve, which is the distal branch of
femoral nerve. The saphenous nerve is advantageous for sensory
augmentation, as it is a sensory-only (non-motor) nerve. The
affector(s) may also be positioned around the ankle to target the
two major branches of the tibial nerve that reach the medial and
lateral underside of the foot for sensory feedback.
[0148] In some embodiments, the device has user input that allows
the wearer to input pain levels that is stored on a memory unit. In
a further extension of this embodiment, the device adjusts
stimulation parameters and/or provides feedback to the wearer based
on history of pain levels. This is applicable to modifying muscle
activation patterns described below.
[0149] In some embodiments, the feedback can be fading feedback
such that at the beginning of treatment an enhanced or higher level
or magnitude of stimulation is provided to the wearer, but as the
treatment progresses, the level or magnitude of the stimulation is
reduced as the wearer's gait improves. This promotes quicker
learning of the desired gait kinematics that reduce KAM and/or knee
pain. For example, FIGS. 17A and 17B illustrate various ways of
providing fading feedback as treatment progresses. The dashed lines
illustrate fading feedback, while the solid line represents the
initial treatment feedback. For example, the feedback level for a
given deviation of the gait parameter from the ideal range can be
reduced, which is shown in the lower dashed lines. Alternatively,
feedback may only be provided to smaller deviations of the gait
parameters as treatment progresses, while either keeping the
feedback level the same for a given deviation, or increasing the
feedback level for a given deviation, or decreasing the feedback
level for a given deviation. This is applicable to modifying muscle
activation patterns described below.
[0150] In some embodiments, individual tuning can be performed. For
a particular wearer, a subset of the key parameters may provide
effective at altering gait and/or reducing pain while the other
parameters may have less or no effect. Therefore, the system,
device, and method can track the wearer's gait kinematics
improvement over time with each parameter and determine which
parameters are most effective for that individual. This is
applicable to modifying muscle activation patterns described
below.
[0151] In some embodiments, the wearer's gait kinematics can be
analyzed to determine which gait parameters are likely to be most
relevant for a particular individual. For example, the deviations
of key gait parameters from the ideal range can be determined, and
the parameters with the largest deviations may be selected as the
basis for the treatment.
[0152] In some embodiments, the wearer may be given different cues
or stimulation, such as audio, vibratory, or electrical, to
determine which cue or stimulation the wearer responds to the best,
which the system and device can select for use during treatment.
This is applicable to modifying muscle activation patterns
described below.
[0153] In some embodiments, the data, which can be stored on the
device or on an external device or the cloud, can be analyzed by a
health care professional that can then modify the treatment in an
open loop manner. The data can be accessed off the device during a
follow up visit, by accessing the data on the cloud, or by sending
the device back to the manufacturer to extract and transmit the
data to the cloud or health care professional. In other
embodiments, the system and device can analyze the data itself and
modify treatment in a closed loop manner. This is applicable to
modifying muscle activation patterns described below.
Method of Modifying Muscle Activation Patterns
[0154] In another embodiment, the wearable unit is in communication
with an electrical stimulation unit that applies stimulation to a
predetermined or predetermined set or subset of muscles that affect
gait pattern (e.g., soleus, gastrocnemius, quadriceps) and a sensor
unit that measures muscle activity (e.g., electromyogram (EMG)).
The simulation unit and the sensor unit can be separate units in
communication, wired or wireless, or housed in the same unit as
shown in FIG. 18. For example, as shown in FIG. 18, an embodiment
of the device that houses electrodes for EMG sensing 1802 and
muscle stimulation 1800. The device can attach to the skin using an
adhesive hydrogel 1804. The device can be applied to multiple
locations on the lower extremity, including, but not limited to,
the top of the foot, the head of the gastrocnemius, or above the
knee across the quadriceps muscle group. Similar to devices and
methods described below, the stimulation can be proportionally
controlled based on measurements of voluntary EMG.
[0155] Reducing knee pain can be accomplished by reducing the load
on the knee. Muscle forces are a large contributor to knee loads
during walking, as shown in FIG. 21. Altering muscle forces during
gait may reduce knee loads. For example, the gastrocnemius muscle
is one of the largest contributors to knee load during walking,
especially during late stance, and thus reducing the activation of
the gastrocnemius muscle during late stance can reduce knee loads.
In some embodiments, the load on the knee can be reduced by
reducing an individual's activation of the gastrocnemius muscle,
which extends from the femur to the heel and causes compression of
the knee when it contracts, and optionally increasing an
individual's activation of the soleus muscle, which extends from
the tibia to the heel, does not cause compression of the knee when
it contracts. FIGS. 22A-22C illustrate the location of the
gastrocnemius 2200 and soleus 2202 muscles on the leg with respect
to the knee 2204.
[0156] Since it is difficult for an individual to detect or control
contraction of the gastrocnemius muscle relative to that of the
soleus muscle, an EMG sensor can be used to detect and monitor
contraction of the gastrocnemius and soleus muscles. When the EMG
sensor detects use of the gastrocnemius muscle, feedback can be
provided so the individual can reduce usage of the gastrocnemius
muscle. When the EMG sensor detects use of the soleus muscle, a
different feedback can be provided so the individual can increase
the usage of the soleus muscle. The feedback can be detectable
stimulation which can be auditory, vibratory, or electrical, for
example. If EMG sensors are placed over both the gastrocnemius and
the soleus, the two feedbacks can be different so that they are
distinguishable by the individual. The feedback can be responsive
and/or fading feedback as described herein with respect to FIGS.
17A and 17B. Such a system, device, and method provides motor
learning or reprogramming therapy that can either train an
individual to increase the use of the soleus and decrease the use
of the gastrocnemius, or increase the excitability of the soleus
and decrease the excitability of the gastrocnemius during gait,
thereby reducing knee load.
[0157] In some embodiments, the system, device, and method can
provide repetitive stimulation, which may be continuous for a
period specified by the user (e.g., patient controlled on/off) or
may be applied during a specific time of the day (i.e., daytime or
known or scheduled activity period), to a desired muscle or
muscles, such as the soleus, to enhance and increase the usage of
this muscle during gait and/or to decrease or inhibit or reduce the
usage of a muscle, such as the gastrocnemius, during gait. The
stimulation can be timed with key gait events such as foot strike,
toe off, early stance phase, and late stance phase, for example,
which can be detected in real time by sensors during the gait cycle
as described herein. Sensors can include EMG, IMU, or pressure
sensors in the shoe or insoles or on the base of the foot, for
example.
[0158] In some embodiments, the stimulation to inhibit or enhance
the usage of muscles can be applied as constant or time stimulation
during specific or predetermined activities that actively and/or
passively engage the muscles of interest, such as stimulation of
the tibial nerve and/or stimulations to identify gastrocnemius and
soleus usage during exercise that engages the calf muscles, such as
toe-raise exercises.
[0159] In some embodiments, a muscle or group of muscles can be
inhibited or have its excitability reduced, such as the
gastrocnemius, instead of or while the other muscle, such as the
soleus, is optionally stimulated, in a reciprocal inhibition
manner. For example, high frequency stimulation at the
neuromuscular junction of the gastrocnemius can decrease the
excitability of corticospinal tracts and lead to inhibition of the
gastrocnemius and reduced knee load during walking. In some
embodiments, the excitability of the gastrocnemius can be decreased
by high frequency stimulation of a peripheral nerve such as the
sciatic or tibial nerve to decrease excitability of its
corticospinal tracts. In some embodiments, the excitability of the
soleus can be increased by repeated peripheral stimulation of the
tibial nerve. In some embodiments, the excitability of the soleus
can be maintained or increased by exciting the peroneal nerve
behind the knee or exciting the sural nerve in order to increase
excitability of soleus motor neuron pool (as measured by means of
the Hoffman reflex, or H reflex).
[0160] In some embodiments, the system, device, and method can
alter gait kinematics and modify muscle activation for a combined
treatment approach. This combined approach is particularly
advantageous because changes in gait kinematics tend to have a
greater effect on the peak knee load during the early stance phase
(load generated after foot strike), which is shown as the first
peak in FIGS. 23A and 23B, and changes in muscle generated force
tend to have a greater effect on the peak knee load during the late
stance phase (load generated prior to toe off), which is shown as
the second peak in FIGS. 23A and 23B. FIG. 23 illustrates a
reduction in knee load due to altering gait kinematics. Reduction
is seen in the first peak of the curve during early stance. FIG.
23B illustrates a reduction in knee load due to reduction of muscle
activation of gastrocnemius. Reduction is seen in the second peak
of the curve during late stance.
Overall Framework
[0161] Treatment of a patient with knee pain from OA can be broken
down into three phases: (1) diagnosis of the patient, (2)
determining treatment based on the diagnosis, and (3) providing the
treatment to the patient.
[0162] Diagnosis can include performing a diagnostic assessment of
the patient using the wearable sensors described herein, such as
IMU, accelerometers, pressure sensors, and EMG, to determine
various gait parameters and muscle activation patterns, such as
foot angle, knee angle, KAM, step width, gastrocnemius activation,
and soleus activation. The patient can be provided (e.g., mail or
pick up at doctor's office) with a kit with sensory prosthetics
(e.g. wearable sensors) and optionally a video camera. In addition,
video taken from a mobile phone or other camera (i.e., webcam,
Kinect) can also be used to determine various gait parameters.
During diagnosis, instructions can be provided to the patient to
perform a predetermined series of tasks or actions, such as walking
and/or toe raises, while using the sensors and/or video. Values
and/or percentages can be assigned to each parameter or
characteristic in order quantify its importance, which may be based
on its magnitude or degree of deviation from an ideal range or
value (degree of abnormality). The values and/or percentages can be
used to identify and/or prioritize which parameters or
characteristic needs the most correction. The patient can wear and
use the sensors during the diagnostic phase for a predetermined or
prescribed period of time (day, week, other interval). Data from
the sensors can be uploaded to the cloud or another computing
device, or the sensors can be sent back to the manufacturer for
data analysis and then refurbished for a new patient.
[0163] The appropriate treatment for each patient can be determined
based on the data generated by the diagnosis by a health care
provider or by the processor unit of the system and device or by an
external computing system. For example, high use of the
gastrocnemius identified during diagnosis may indicate that the
system and device should focus on training the patient to reduce
use of the gastrocnemius. The diagnosis may also indicate that foot
angle needs correction, but at a lower priority than gastrocnemius
correction. In some embodiments, the treatment can be prescribed to
focus on modifying one parameter or characteristic at a time, based
on the priority identified during diagnosis, because it may be
difficult for a patient to work on changing multiple parameters or
characteristics simultaneously. In addition, working on a single
parameter or characteristic may only require providing a single
stimulation or cue, while working on multiple parameters or
characteristics simultaneously would require providing multiple
stimulations or cues that can be distinguished by the patient. The
stimulation dosing can be optimized to promote or enhance motor
and/or neural entrainment, using for example, responsive or
proportional feedback/stimulation and/or fading feedback.
[0164] Once the treatment plan has been determined, the patient can
be provided (e.g., mail or pick up at doctor's office) with the
appropriate treatment system and device, which can be programmed to
execute the treatment plan. The patient can be instructed, on a
mobile phone app for example, on how and where to place the various
components of the system and device on the patient's body. In some
embodiments, the initial kit can include both the diagnostic
sensors and treatment system and device, or the initial kit can
include a system and device that performs both the diagnostic and
treatment functions. In some embodiments, the system and device is
designed to operate for a predetermined length of time, such as up
to 30, 60, or 90 days, at which point the patient exchanges the old
system and device with a new system and device. The old system and
device can be returned to the manufacturer for refurbishing.
[0165] When a feature or element is herein referred to as being
"on" another feature or element, it can be directly on the other
feature or element or intervening features and/or elements may also
be present. In contrast, when a feature or element is referred to
as being "directly on" another feature or element, there are no
intervening features or elements present. It will also be
understood that, when a feature or element is referred to as being
"connected", "attached" or "coupled" to another feature or element,
it can be directly connected, attached or coupled to the other
feature or element or intervening features or elements may be
present. In contrast, when a feature or element is referred to as
being "directly connected", "directly attached" or "directly
coupled" to another feature or element, there are no intervening
features or elements present. Although described or shown with
respect to one embodiment, the features and elements so described
or shown can apply to other embodiments. It will also be
appreciated by those of skill in the art that references to a
structure or feature that is disposed "adjacent" another feature
may have portions that overlap or underlie the adjacent
feature.
[0166] Terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. For example, as used herein, the singular forms "a",
"an" and "the" are intended to include the plural forms as well,
unless the context clearly indicates otherwise. It will be further
understood that the terms "comprises" and/or "comprising," when
used in this specification, specify the presence of stated
features, steps, operations, elements, and/or components, but do
not preclude the presence or addition of one or more other
features, steps, operations, elements, components, and/or groups
thereof. As used herein, the term "and/or" includes any and all
combinations of one or more of the associated listed items and may
be abbreviated as "/".
[0167] Spatially relative terms, such as "under", "below", "lower",
"over", "upper" and the like, may be used herein for ease of
description to describe one element or feature's relationship to
another element(s) or feature(s) as illustrated in the figures. It
will be understood that the spatially relative terms are intended
to encompass different orientations of the device in use or
operation in addition to the orientation depicted in the figures.
For example, if a device in the figures is inverted, elements
described as "under" or "beneath" other elements or features would
then be oriented "over" the other elements or features. Thus, the
exemplary term "under" can encompass both an orientation of over
and under. The device may be otherwise oriented (rotated 90 degrees
or at other orientations) and the spatially relative descriptors
used herein interpreted accordingly. Similarly, the terms
"upwardly", "downwardly", "vertical", "horizontal" and the like are
used herein for the purpose of explanation only unless specifically
indicated otherwise.
[0168] Although the terms "first" and "second" may be used herein
to describe various features/elements (including steps), these
features/elements should not be limited by these terms, unless the
context indicates otherwise. These terms may be used to distinguish
one feature/element from another feature/element. Thus, a first
feature/element discussed below could be termed a second
feature/element, and similarly, a second feature/element discussed
below could be termed a first feature/element without departing
from the teachings of the present invention.
[0169] Throughout this specification and the claims which follow,
unless the context requires otherwise, the word "comprise", and
variations such as "comprises" and "comprising" means various
components can be co-jointly employed in the methods and articles
(e.g., compositions and apparatuses including device and methods).
For example, the term "comprising" will be understood to imply the
inclusion of any stated elements or steps but not the exclusion of
any other elements or steps.
[0170] As used herein in the specification and claims, including as
used in the examples and unless otherwise expressly specified, all
numbers may be read as if prefaced by the word "about" or
"approximately," even if the term does not expressly appear. The
phrase "about" or "approximately" may be used when describing
magnitude and/or position to indicate that the value and/or
position described is within a reasonable expected range of values
and/or positions. For example, a numeric value may have a value
that is +/-0.1% of the stated value (or range of values), +/-1% of
the stated value (or range of values), +/-2% of the stated value
(or range of values), +/-5% of the stated value (or range of
values), +/-10% of the stated value (or range of values), etc. Any
numerical values given herein should also be understood to include
about or approximately that value, unless the context indicates
otherwise. For example, if the value "10" is disclosed, then "about
10" is also disclosed. Any numerical range recited herein is
intended to include all sub-ranges subsumed therein. It is also
understood that when a value is disclosed that "less than or equal
to" the value, "greater than or equal to the value" and possible
ranges between values are also disclosed, as appropriately
understood by the skilled artisan. For example, if the value "X" is
disclosed the "less than or equal to X" as well as "greater than or
equal to X" (e.g., where X is a numerical value) is also disclosed.
It is also understood that the throughout the application, data is
provided in a number of different formats, and that this data,
represents endpoints and starting points, and ranges for any
combination of the data points. For example, if a particular data
point "10" and a particular data point "15" are disclosed, it is
understood that greater than, greater than or equal to, less than,
less than or equal to, and equal to 10 and 15 are considered
disclosed as well as between 10 and 15. It is also understood that
each unit between two particular units are also disclosed. For
example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are
also disclosed.
[0171] Although various illustrative embodiments are described
above, any of a number of changes may be made to various
embodiments without departing from the scope of the invention as
described by the claims. For example, the order in which various
described method steps are performed may often be changed in
alternative embodiments, and in other alternative embodiments one
or more method steps may be skipped altogether. Optional features
of various device and system embodiments may be included in some
embodiments and not in others. Therefore, the foregoing description
is provided primarily for exemplary purposes and should not be
interpreted to limit the scope of the invention as it is set forth
in the claims.
[0172] The examples and illustrations included herein show, by way
of illustration and not of limitation, specific embodiments in
which the subject matter may be practiced. As mentioned, other
embodiments may be utilized and derived there from, such that
structural and logical substitutions and changes may be made
without departing from the scope of this disclosure. Such
embodiments of the inventive subject matter may be referred to
herein individually or collectively by the term "invention" merely
for convenience and without intending to voluntarily limit the
scope of this application to any single invention or inventive
concept, if more than one is, in fact, disclosed. Thus, although
specific embodiments have been illustrated and described herein,
any arrangement calculated to achieve the same purpose may be
substituted for the specific embodiments shown. This disclosure is
intended to cover any and all adaptations or variations of various
embodiments. Combinations of the above embodiments, and other
embodiments not specifically described herein, will be apparent to
those of skill in the art upon reviewing the above description.
* * * * *