U.S. patent application number 10/353840 was filed with the patent office on 2003-08-21 for compact posterior stop for an ankle-foot orthosis.
Invention is credited to Hinshon, Patrick Scott.
Application Number | 20030158506 10/353840 |
Document ID | / |
Family ID | 27663005 |
Filed Date | 2003-08-21 |
United States Patent
Application |
20030158506 |
Kind Code |
A1 |
Hinshon, Patrick Scott |
August 21, 2003 |
Compact posterior stop for an ankle-foot orthosis
Abstract
The present invention is directed, to an improved orthosis and
posterior plantar flexion stop for the orthosis, as well as to
methods of making and using the orthosis and posterior stop, plus
components used to make the orthosis and stop. The ankle-foot
orthosis and plantar flexion stop of the present invention improve
on the function and performance of the orthosis, while also making
the orthosis attractive and easier to use than prior devices.
Inventors: |
Hinshon, Patrick Scott;
(Maplewood, MN) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Family ID: |
27663005 |
Appl. No.: |
10/353840 |
Filed: |
January 28, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60351511 |
Jan 28, 2002 |
|
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Current U.S.
Class: |
602/16 ;
602/27 |
Current CPC
Class: |
A61F 5/0127
20130101 |
Class at
Publication: |
602/16 ;
602/27 |
International
Class: |
A61F 005/00 |
Claims
I claim:
1. A stop mechanism for restricting the motion of an ankle-foot
orthosis, the stop mechanism comprising: a removable stopping
bumper configured to contact a bumper rest, the removable stopping
bumper comprising a head and a stem, the head configured to contact
the bumper rest, the stem configured for insertion into a cavity in
an orthosis, wherein the bumper head has a larger horizontal cross
section than the bumper stem.
2. The stop mechanism of claim 1, wherein the bumper head is
retained in the cavity of an orthosis by a friction fit.
3. The stop mechanism of claim 1, further comprising: a cavity
formed from a wall of an orthosis; wherein the bumper head overlaps
the stem on at least three sides by a distance within 20 percent of
the average thickness of the wall forming the cavity of the
orthosis.
4. The stop mechanism of claim 1, wherein the stem is configured to
be at least partially exposed on the inside of an orthosis when the
stem is installed in the orthosis.
5. The stop mechanism of claim 1, wherein the stem is configured to
be installed into a cavity in an orthosis, the cavity surrounding
less than 330 degrees of perimeter of the stem.
6. The stop mechanism of claim 1, wherein: the stem has a first
surface configured to face the inside of an orthosis; the head has
a first surface configured to face the inside of an orthosis; and
the first surface of the stem and first surface of the head are
continuous.
7. The stop mechanism of claim 1, wherein: the stem has a first
surface configured to face the inside of an orthosis; the head has
a first surface configured to face the inside of an orthosis; and
the first surface of the stem and first surface of the head are
offset by less than 2.0 millimeters.
8. The stop mechanism of claim 1, wherein: the stem has a first
surface configured to face the inside of an orthosis; the head has
a first surface configured to face the inside of an orthosis; and
the first surface of the stem and first surface of the head are
offset by less than 4.0 millimeters.
9. The stop mechanism of claim 1, wherein the bumper head has a
horizontal cross section at least 50 percent greater than the
horizontal cross section of the stem, the cross sections taken at
substantially the vertical center of each of the head and stem.
10. The stop mechanism of claim 1, wherein the bumper head has a
horizontal cross section at least 100 percent greater than the
horizontal cross section of the stem, the cross sections taken at
substantially the vertical center of each of the head and stem.
11. The stop mechanism of claim 1, wherein the bumper rest
comprises a first surface configured for receiving the bumper head,
and wherein said first surface contains an exposed molding blank at
least partially surrounded by a thermoformed wall.
12. The stop mechanism of claim 11, wherein the thermoformed wall
is contiguous and integrally formed with the wall of an
orthosis.
13. The stop mechanism of claim 11, wherein the exposed molding
blank has a horizontal cross-sectional area substantially equal to
the horizontal cross sectional area of the stem of the bumper
head.
14. The stop mechanism of claim 11, wherein the exposed molding
blank has a horizontal cross-sectional area that is within 50
percent of the horizontal cross sectional area of the stem of the
bumper head.
15. The stop mechanism of claim 1, wherein the stop has a total
length of less than or equal to 3 centimeters.
16. The stop mechanism of claim 1, wherein the stop has a total
length of less than or equal to 4 centimeters.
17. The stop mechanism of claim 1, wherein stem of the bumper head
has an asymmetric horizontal cross section, and wherein the
posterior of the cross section is wider than the anterior of the
cross section.
18. The stop mechanism of claim 1, wherein the stem further
comprises at least one raised protrusion, the protrusion configured
and arranged to engage a recess in a wall of the orthosis cavity,
thereby assisting in retention of the stem within the cavity in the
orthosis, while still permitting removal of the stem.
19. A stop mechanism for an orthosis, the stop mechanism
comprising: a first portion integrally formed from a single piece
of thermoformed plastic used to form a wall of the orthosis; and a
second portion partially surrounded by the first portion.
20. The stop mechanism of claim 19, wherein the stop mechanism has
a length of less than 4 centimeters.
22. The stop mechanism of claim 19, wherein the first and second
portions comprise a bumper rest.
23. The stop mechanism of claim 19, wherein the stop mechanism
comprises a bumper rest having a width measured perpendicular to
the sagittal plane approximately 3 times the thickness of the wall
of the orthosis proximate the stop mechanism.
24. The stop mechanism of claim 19, wherein the stop mechanism
comprises a bumper rest having a width measured perpendicular to
the sagittal plane of approximately from 2 to 4 times the thickness
of the wall of the orthosis proximate the stop mechanism.
25. The stop mechanism of claim 19, wherein the stop mechanism
comprises a bumper rest having a width measured perpendicular to
the sagittal plane of less than 4 times the thickness of the wall
of the orthosis proximate the stop mechanism.
26. The stop mechanism of claim 19, wherein the stop mechanism
comprises a bumper rest having a depth measured parallel to the
sagittal plane of approximately 3 times the thickness of the wall
of the orthosis proximate the stop mechanism.
27. The stop mechanism of claim 19, wherein the stop mechanism
comprises a bumper rest having a depth measured parallel to the
sagittal plane of less than 3 times the width of the wall of the
orthosis proximate the stop mechanism.
28. The stop mechanism of claim 19, wherein the stop mechanism
comprises a bumper rest having a depth measured parallel to the
sagittal plane of less than 2.5 times the width of the wall of the
orthosis proximate the stop mechanism.
29. The stop mechanism of claim 19, wherein the stop mechanism
comprises a bumper rest having a depth measured parallel to the
sagittal plane of less than 2 times the width of the wall of the
orthosis proximate the stop mechanism.
30. The stop mechanism of claim 19, wherein the stop mechanism
comprises a bumper rest having a vertical length of less than 5
times the width of the wall of the orthosis proximate the stop
mechanism.
31. The stop mechanism of claim 19, wherein the stop mechanism
comprises a bumper rest having a vertical length of less than 4
times the width of the wall of the orthosis proximate the stop
mechanism.
32. The stop mechanism of claim 19, wherein the stop mechanism
comprises a bumper rest having a vertical length of less than 3
times the width of the wall of the orthosis proximate the stop
mechanism.
33. The stop mechanism of claim 1, wherein the bumper head
comprises thermoplastic polyurethane with a Shore hardness of at
least 55D according to ASTM D 2240 (ISO 868).
34. The stop mechanism of claim 1, wherein the bumper head
comprises a thermoplastic polyurethane with a Shore hardness of at
least 57D according to ASTM D 2240 (ISO 868).
35. The stop mechanism of claim 1, wherein the bumper head
comprises a thermoplastic polyurethane having less than 10 percent
deflection at 1500 pounds per square inch of compressive load
according to ASTM D575.
36. The stop mechanism of claim 1, wherein the bumper head
comprises a thermoplastic polyurethane having less than 15 percent
deflection at 1500 pounds per square inch of compressive load
according to ASTM D575.
37. The stop mechanism of claim 1, wherein the bumper head
comprises a thermoplastic polyurethane having less than 20 percent
deflection at 1500 pounds per square inch of compressive load
according to ASTM D575.
38. The stop mechanism of claim 1, wherein the bumper head
comprises a thermoplastic polyurethane having less than 10 percent
deflection at 1000 pounds per square inch of compressive load
according to ASTM D575.
39. The stop mechanism of claim 1, wherein the bumper head
comprises a polyester-based polyurethane having less than 10
percent deflection at 1000 pounds per square inch of compressive
load according to ASTM D575.
40. The stop mechanism of claim 1, wherein the bumper head
comprises a polyester-based polyurethane having a flexural modulus
of less than 37,000 pounds per square inch at a temperature of 23
degrees Celsius using ASTM D790 (ISO 178).
41. The stop mechanism of claim 1, wherein the bumper head
comprises a polyester-based polyurethane having a flexural modulus
of greater than 20,000 pounds per square inch at a temperature of
23 degrees Celsius using ASTM D790 (ISO 178).
42. A stop mechanism for restricting the motion of an ankle-foot
orthosis, the stop mechanism comprising: a removable stopping
bumper configured to contact a bumper rest, the removable stopping
bumper comprising a head and a stem, the head configured to contact
the bumper rest, the stem configured for insertion into a cavity in
an orthosis, wherein the bumper head has a larger horizontal cross
section than the bumper stem; wherein the bumper rest comprises a
first surface configured for receiving the bumper head, and wherein
said first surface contains an exposed molding blank at least
partially surrounded by a thermoformed wall, and the stop mechanism
comprises a bumper rest having a vertical length of less than 6
times the width of the wall of the orthosis proximate the stop
mechanism and a depth of less than 1 centimeter and a width of less
than 1 centimeter.
Description
PRIORITY
[0001] This application claims priority to U.S. provisional patent
application Serial No. 60/351,511 filed Jan. 28, 2002.
FIELD OF THE INVENTION
[0002] The present invention is directed to an improved ankle-foot
orthosis, an improved posterior plantar stop for the orthosis,
methods of making the orthosis and posterior stop, materials used
to form the orthosis and posterior stop, and therapeutic procedures
using the orthosis and posterior stop.
BACKGROUND OF THE INVENTION
[0003] The human foot is designed so that it can rotate and pivot
with regard to the lower leg, and such movements are essential to
walking. One primary movement is plantar flexion, which is downward
motion of the foot that occurs in the sagittal plane. In some
circumstances it is necessary to limit plantar flexion to less than
90 degrees. For example, individuals with paralysis or weakness of
the dorsi flexion muscle group (which lifts the foot) typically
have trouble raising their foot, such as when they're walking. This
dorsi flexion problem can result in tripping and falling as the
front of the foot catches on obstacles. Also, individuals with
excessive plantar flexion sometimes compensate when walking by
lifting their foot and leg higher than normal in order to lift the
front of their foot off of the ground. This unnatural lifting of
the leg and foot results in a modified gait that is sometimes
referred to as a steppage gait because it bears resemblance to the
gait of a high-stepping horse. Walking with a steppage gait is
inefficient and tiresome, and can also lead to other undesirable
stresses on the body.
[0004] Various ankle-foot orthosis devices have been developed to
prevent excessive plantar flexion. For example, a solid ankle brace
can be placed in an individual's shoe so as to prevent flexing at
the ankle joint. These braces may be improved upon by allowing a
pivoting movement at the ankle joint to permit the angle between
the foot and lower leg to decrease in size, while using a stop to
prevent the foot from exceeding a 90 degree angle with the lower
leg. These improved articulating orthosis offer significant
advantages over prior rigid devices, including improved comfort,
allowing a more natural walking motion by the patient, and reducing
stiffness by promoting flexing of the ankle joint.
[0005] A number of companies currently make articulating orthosis
and components for these orthosis, including components for the
ankle joints and posterior stops. Unfortunately, many of these
adjustable ankle-foot orthosis have significant shortcomings. For
one, manufacture of the posterior stop is often time consuming and
tedious, involving careful alignment of small components that must
be delicately adjusted after installation. In addition, these
posterior stops are often much larger and less attractive than
desired. The problems with the large size of the stops are not
limited to aesthetics, because their large size generally requires
that at least part of the stop extend below the back of the shoe.
Also, the stops are so large that they do not comfortably fit
within a shoe, and patients frequently need two pairs of shoes of
different sizes, or must modify their shoes (such as by removing
part of the shoe's back or stretching the shoe to make it larger)
to permit wearing of these orthosis with large posterior stops.
[0006] Therefore, a need exists for an improved ankle-foot
posterior orthosis that is less cumbersome to make and use, while
also being attractive, durable, and small.
SUMMARY OF THE INVENTION
[0007] The present invention is directed, in part, to an improved
orthosis and posterior plantar flexion stop for the orthosis, as
well as to methods of making and using the orthosis and posterior
stop, plus components used to make the orthosis and stop. The
ankle-foot orthosis and plantar flexion stop of the present
invention improve on the function and performance of the orthosis,
while also making the orthosis attractive and easier to use than
prior devices.
[0008] The improved orthosis has a compact, adjustable, easily
manufactured stop that is both durable and functional. Manufacture
of the orthosis and stop utilizes a three dimensional molding blank
configured for easy and precise fabrication and positioning on the
orthosis. As described below, the molding blank is used to form a
cavity in the walls of the orthosis for retaining a stopping
bumper, while also forming a bumper rest with which the stopping
bumper makes contact.
[0009] The improved ankle-foot orthosis and posterior stop also
significantly reduce or eliminate the clicking noise created by
existing orthosis stops. This reduction in noise is accomplished by
using a superior thermomolded composition well suited to the
functions necessary for a posterior stop. Thus, the improved
orthosis and stop are able to be relatively quiet, yet allow
precise sagittal adjustability and durability.
[0010] Other benefits of the improved orthosis and stop include the
ability to produce a very compact posterior stop that decreases the
length, width, and thickness necessary to produce a functioning
stop. In particular, the width and thickness of the posterior stop
can be significantly reduced, while the length can also be limited.
In addition to limiting the length of the stop, the position of the
stop components can be improved so that they do not excessively
intrude into a shoe of a patient. In doing so the invention results
in a more attractive and comfortable orthosis that is well received
by patients.
[0011] The compact stop is also a major functional improvement
because it permits a patient greater freedom in choosing footwear,
while maintaining sagital alignment over time in relationship to
the durability of the materials used to make the orthosis and stop.
Many current orthosis stops are so bulky, and positioned so low
along a patient's ankle, that they significantly intrude into a
patient's shoe. These bulky stops often necessitate buying two
pairs of shoes of different sizes, modification of shoes to allow
for the bulky stop, or limitations on what kind of shoes are worn.
The present invention significantly reduces or eliminates the need
to make these adjustments in a patient's footwear.
[0012] A further aspect of the present invention is that adult
patients can temporarily remove the bumper of the posterior stop in
order to drive an automobile or perform other acts that require
plantar flexion of more than 90 degrees, and then easily reinsert
the motion stop to restore its function for ambulation. This
modification is significant because it allows a patient to perform
important daily routines with minimum intrusion and no sensitive
adjustment or alignment of the motion stop. Also, different bumpers
can be interchanged to create different stop angles, including
shorter bumpers that allow some posterior flexion. Such bumpers are
useful when wearing footwear that has the heel elevated slightly
above the front of the foot. Without such bumper stops a patient
will sometimes resort to unnatural knee-bending when wearing these
inclined shoes. Yet another further improvement of the invention is
that it can be used to increase dorsi flexion in patients by
providing customized, precise nocturnal gastroc stretch, in which
the amount of stretch can be precise and customized.
[0013] Other features and advantages of the invention, including
methods of making an orthosis, will be apparent from the following
detailed description of the invention and the claims. The above
summary of principles of the disclosure is not intended to describe
each illustrated embodiment or every implementation of the present
disclosure. The detailed description that follows more particularly
exemplifies certain embodiments utilizing the principles disclosed
herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The invention will be more fully explained with reference to
the following drawings.
[0015] FIG. 1 shows a simplified side perspective view of an
ankle-foot orthosis, the orthosis having a posterior plantar
flexion stop constructed and arranged in accordance with an
implementation of the invention.
[0016] FIG. 2A shows an enlarged partial view of the plantar
flexion stop of FIG. 1, with the orthosis in a dorsi flexion
position and the stop not engaged.
[0017] FIG. 2B shows an enlarged partial view of the posterior
plantar flexion stop of FIG. 1, showing the orthosis in a neutral
flexion position with the stop engaged.
[0018] FIG. 3A shows an enlarged cross sectional view of a
posterior plantar flexion stop, the cross section taken along lines
3-3 of FIG. 2A.
[0019] FIG. 3B shows an enlarged top view of the top of the bumper
rest of FIG. 3A.
[0020] FIG. 4A shows an enlarged perspective view of a molding
blank for a plantar flexion stop made in accordance with an
implementation of the invention.
[0021] FIG. 4B shows an anterior view of a molding blank for a
plantar flexion stop made in accordance with an implementation of
the invention.
[0022] FIG. 4C shows an enlarged cross sectional view of the
molding blank of FIG. 4A, the cross section taken along line C-C of
FIG. 4B.
[0023] FIG. 4D shows an enlarged cross sectional view of the
molding blank of FIG. 4A, the cross section taken along line D-D of
FIG. 4B.
[0024] FIG. 5A is a side plan view of the molding blank of FIG. 4A
positioned on a model of a leg prior to casting an orthosis.
[0025] FIG. 5B is a bottom plan view of the molding blank of FIG.
5A positioned on a model of a leg prior to casting an orthosis.
[0026] FIG. 5C is a perspective view of a molding plank positioned
within a partially completed orthosis made in accordance with the
invention.
[0027] FIG. 5D is a posterior elevational view of a partially
completed orthosis constructed in accordance with the
invention.
[0028] FIG. 5E is an enlarged perspective view of the top of a
partially completed two-piece articulating orthosis after the top
portion and bottom portion have been separated from one another,
but before excess portions of the orthosis have been removed.
[0029] FIG. 5F is an enlarged perspective view of the top of an
orthosis after the top portion and bottom portion have been
separated from one another, and after excess portions of the
orthosis have been removed.
[0030] FIG. 5G is a perspective view showing removal of the molding
blank from the top section of the orthosis.
[0031] FIG. 5H is a perspective view of a stopping bumper being
inserted into a channel in the top portion of an orthosis.
[0032] FIG. 6A shows an enlarged perspective view of a stopping
bumper for a plantar flexion stop made in accordance with an
implementation of the invention.
[0033] FIG. 6B enlarged cross sectional view of the motion stop of
FIG. 6A, the cross section taken along line B-B of FIG. 6A.
[0034] FIG. 7 is a perspective view of a molding blank constructed
in accordance with an implementation of the invention.
[0035] FIG. 8A is a perspective view of a plantar stop kit
constructed and arranged in accordance with the present
invention.
[0036] FIG. 8B is a plurality of views of stopping bumpers from the
plantar stop kit of FIG. 8A.
[0037] While principles of the invention are amenable to various
modifications and alternative forms, specifics thereof have been
shown by way of example in the drawings and will be described in
detail. It should be understood, however, that the intention is not
to limit the invention to the particular embodiments described. On
the contrary, the intention is to cover all modifications,
equivalents, and alternatives falling within the spirit and scope
of the disclosure and claims.
DETAILED DESCRIPTION OF THE INVENTION
[0038] Stop mechanisms, also referred to as plantar stops and
motion limiters, made in accordance with the invention generally
restrict the motion of an ankle-foot orthosis by limiting plantar
flexion. The stop mechanisms of the present invention are
particularly useful because they are designed as part of a complete
system that allows for the creation of particularly small, but
highly functional, posterior plantar stops. In addition, the
plantar stops can be made easily with a minimum of steps and tools,
and can be produced quickly.
[0039] The stop mechanisms typically include a removable stopping
bumper configured to contact a bumper rest, the removable stopping
bumper comprising a head and a stem, the head configured to contact
the bumper while the stem is configured for insertion into a cavity
in an orthosis. The stopping bumper is removable from the cavity in
the orthosis so that it can be replaced with a bumper of a
different thickness in order, for example, to allow a patient
greater plantar flexion for some activities (such as driving a
car), in order to accommodate different footwear, or to promote
therapeutic nocturnal gastroc stretch.
[0040] Generally the bumper head has a larger horizontal cross
section than the bumper stem. The bumper rest typically comprises a
surface configured for receiving the bumper head, and this surface
contains a portion of an exposed molding blank partially surrounded
by a thermoformed wall. The thermoformed wall partially surrounding
the molding blank is usually contiguous and integrally formed with
the wall of the orthosis from a single piece of thermoplastic
material. Indeed, the molding blank is generally configured so that
it is not necessary to use anything other than the wall of the
orthosis to hold the blank in place. In this regard it is possible
to hold the blank in place without using extra pieces of
thermoforming material.
[0041] In most implementations the molding blank is not entirely
surrounded by the thermoformed wall because those portions of the
molding blank that were originally in contact with the mold during
thermal forming of the orthosis are not surrounded by thermoformed
wall. Thus, part of the molding blank can be left exposed on the
interior of the orthosis. However, the molding blank does not fall
out of the exposed gap in the wall because the molding blank has a
shape that is wider at its posterior than this exposed gap that is
formed at its anterior.
[0042] Aspects of the invention will be better understood by
reference to the figures. FIG. 1 shows an articulating ankle-foot
orthosis 20 incorporating a plantar flexion stop 22 constructed and
arranged in accordance with the invention. The orthosis 20 has an
upper portion 24 configured to retain a patient's lower leg, plus a
lower portion 26 configured to retain a patient's foot. Ankle joint
28 allows the upper and lower portions 24, 26 of the orthosis 20 to
pivot with respect to one another, typically along an axis that
corresponds substantially to the axis of the patient's own ankle.
The plantar flexion stop 22 restricts excessive flexing of the foot
by preventing plantar flexion at an angle greater than 90 degrees
between the foot and lower leg (with some exceptions wherein
slightly greater than 90 degree extension is desired). The flexion
stop 22 of the invention provides a compact, yet durable, stop that
is easy to manufacture, uniquely adjustable, and aesthetically
pleasing.
[0043] In reference now to FIGS. 2A and 2B, a plantar flexion stop
22 made in accordance with the invention is shown in closeup view
with a portion of the orthosis also shown in cut-away views. The
posterior flexion stop 22 has two primary elements: a removable
stopping bumper 30 and a bumper rest 32. In general, the stopping
bumper 30 is positioned above the bumper rest 32 (although the
opposite arrangement is also possible). Stopping bumper 30
typically snaps in place into a cavity or groove formed within the
thermoformed wall of the upper portion 24 of the orthosis. Bumper
rest 32 is positioned within the wall, and indeed comprises part of
the wall, of the lower portion 26 of the orthosis. In most, but not
all, implementations of the invention, the bumper rest 32 is not
removable from the orthosis 20, unlike the stopping bumper 30. FIG.
2A shows the orthosis and foot in a dorsi flexion position, wherein
there is a gap between the stopping bumper 30 and bumper rest 32.
FIG. 2B shows the orthosis and foot in a neutral flexion position,
with stopping bumper 30 in contact with the bumper stop 32, thereby
preventing plantar flexion.
[0044] The specific elements of the plantar flexion stop 22 are
shown in more detail in FIGS. 3A and 3B. FIG. 3A is a vertical
cross-section of a stopping bumper 30 and bumper rest 32 made in
accordance with an implementation of the invention. FIG. 3B is a
top view of a bumper rest 32 made in accordance with the invention.
The stopping bumper 30 in the depicted embodiment includes a stem
31 and a head 33. The head 33 is configured to make contact with
the bumper rest 32 in order to stop plantar flexion. The stem 31 is
designed such that it can be snapped in place within a channel 35
formed on the inside of the upper portion 24 of the orthosis. This
channel 35 is typically formed using a molding blank, which is
removed and replaced with the stem 31. In some implementations a
bump or ridge 36 is made in the stem 31, this bump or ridge 36 is
configured to engage a corresponding depression in cavity 35,
thereby helping to keep the stopping bumper 30 in place. Multiple
bumps or ridges 36 can be used in a cavity to promote engagement of
the stem 31 in the cavity 35.
[0045] The stem 31 is tightly held within cavity 35. Typically, the
stem 31 is held in place on at least three sides by the
thermoformed material that forms the rest of the orthosis described
herein. In some implementations the thermoformed material is nearly
as thick as the stem, while in other implementations the stem is
considerably thicker than the thermoformed material. The bumper
head 33 extends out from the cavity, and is typically considerably
wider than the stem 31. Also, bumper head 33 generally extends
beyond the perimeter of the stem so as to substantially overlap
portions of the of wall the upper portion 24 of the orthosis that
forms cavity 35. Heads 33 of various thicknesses can be used to
form the stopping bumper 30. In addition, the head 33 is typically
constructed of a material that can be ground down or cut if
necessary to optimize fit and comfort for a patient. Opposite the
stopping bumper 30 is the bumper rest 32. The top of the bumper
rest 32 typically has exposed portions of a molding blank that have
been at least partially encased within the wall 37 of the bottom 26
of the orthosis. Manufacture of this integrated bumper rest 32 is
described in greater detail below.
[0046] The invention is further directed to an improved orthosis
for an ankle-foot joint, the orthosis comprising a first portion
configured to be secured to the foot of a patient; a second portion
configured to be secured to the lower leg of a patient; a joint
configured to allow the first portion and second portion to pivot
with regard to one another; and a stop mechanism positioned on the
posterior of the orthosis, the stop mechanism comprising a bumper
and a bumper rest; wherein the bottom of the stop mechanism is
positioned above the axis of rotation in the sagittal plane of the
ankle. It will be appreciated that the distance above the axis of
rotation of the ankle will vary depending upon the size of the
brace, and thus the absolute distance will often be quite small on
a pediatric brace compared to an adult brace. However, in some
implementations the stop mechanism is positioned at least 1.0
centimeter above the axis of rotation in the sagittal plane of the
ankle, more desirably at least 2.0 centimeters, and even more
desirably at least 2.5 centimeters above the axis of rotation in
the sagittal plane of the ankle. In some implementations this
distance is greater than 4.0 centimeters above bottom of the
orthosis. Also, the compact stop mechanism, and in particular the
compact bumper rest, allows for placement of the bottom of the
bumper stop relatively high off the bottom of the orthosis, thereby
permitting a patient to have greater options in what kind of
footwear the will use.
[0047] One of the significant aspects of the present invention is
that it allows a motion stop to be made that is extremely compact.
This can be accomplished, in part, by configuring a minimally sized
cavity or recess in the wall of the orthosis for retaining the stem
of the head of the stopping bumper, while also permitting the use
of a small bumper rest. Rather than surrounding the stem on all
sides, thereby necessitating a thick stop, the present invention
permits forming a cavity in the wall of the orthosis that does not
entirely encase the interior of the stem, thereby reducing the
overall thickness of the stop without reducing performance.
[0048] While the actual dimensions of the stop mechanism will vary
with the size of the orthosis and the thickness of the thermoformed
walls of the orthosis, in some implementations the bumper rest has
a width measured perpendicular to the sagittal plane of
approximately 3 times the thickness of the wall of the orthosis
proximate the stop mechanism. Indeed, in certain embodiments, the
bumper rest can have a width measured perpendicular to the sagittal
plane of approximately 2 to 4 times the thickness of the wall of
the orthosis proximate the stop mechanism. Generally this width is
not less than two times the thickness of the wall of the orthosis,
because the stop contains two sides formed from the same sheet.
Also, to keep the stop mechanism compact, it is often desirable
that the bumper rest have a width measured perpendicular to the
sagittal plane of less than 4 times the thickness of the wall of
the orthosis proximate the stop mechanism.
[0049] Similarly, the posterior stop desirably has a relatively
small overall thickness as measured parallel to the sagittal plane.
This thickness can be, for example, approximately 3 or less times
the thickness of the wall of the orthosis proximate the posterior
stop. In some implementations the thickness measured parallel to
the sagittal plane is less than 2.5 times the thickness of the wall
of the orthosis proximate the stop mechanism, while in certain
implementations this distance is less than 2.0 times the thickness
of the wall.
[0050] The length (also referred to as height) of the entire stop
mechanism is generally also kept to a minimum, although this
dimension is sometimes less important than width and thickness of
the stop because it has a lesser impact on comfort and footwear
choices. Thus, the stop mechanism typically has a vertical length
significantly less than 7 centimeters, more typically less than 5
centimeters, and desirably less than 4 or 3 centimeters. The
individual components of the stop mechanism, such as the stopping
bumper and bumper rest, are similarly slight in size. For example,
the bumper rest can have a length that is less than 5 times the
thickness of the wall of the orthosis proximate the stop mechanism,
alternatively less than 4 times the width of the wall of the
orthosis proximate the stop mechanism, and even less than 3 times
the width of the wall of the orthosis proximate the stop
mechanism.
[0051] One aspect of the present invention is an improved molding
blank used to form a cavity in the posterior of an orthosis for
insertion of the stopping bumper, as well as to assist in the
formation of the bumper rest. The molding blank is typically an
elongate piece of plastic having an upper end and a lower end. In
some embodiments a cut indicator is placed in the body of the
molding blank, the cut indicator visible after forming of the wall
of the orthosis, and providing an indication of where the partially
formed orthosis should be cut to form a two-part orthosis. The cut
indicator can comprise, for example, a hole through the body of the
molding blank. Also, the molding blank can include a grind
indicator in the body of the molding blank, the grind indicator
visible after forming of the wall of the orthosis, and providing an
indication of how much of the orthosis should be removed during
processing after the two pieces of the orthosis have been cut
apart. The grind indicator can be, for example, a horizontal bar
across the body of the molding blank. In some implementations the
molding blank further comprises a recess (or protrusion) configured
to receive a tool for removing at least a portion of the molding
blank from the orthosis, such as a recess configured to receive a
screw driver for forcing out a portion of the molding blank from
the orthosis.
[0052] Details of a molding blank 40 manufactured in accordance
with the invention are shown in FIGS. 4A to 4D. FIG. 4A shows a
perspective view of the molding blank 40. FIG. 4B shows an anterior
view of the molding blank 40. FIG. 4C shows a cross-section of the
molding blank along the sagittal plane. FIG. 4D is a horizontal
cross-section. The molding blank 40 shown in these figures can be
used to produce a plantar stop that has one removable portion (the
bottom of the blank as shown in FIG. 4A). Thus, with this molding
blank approximately half of the blank is left within the orthosis
to form a portion of the bumper rest. Alternatively, in some
implementations the molding blank 40 has two removable portions,
thereby allowing the formation of two cavities for receiving stems
of bumper stops. Molding blank 40 of FIG. 4A has a narrow side 42
and a wide side 43. This narrow side 42 is generally placed such
that it is facing a foot mold during thermoforming of the orthosis.
In most implementations the narrow side 42 is in actual contact
with the foot mold during thermoforming. Thus, this narrow face is
not covered by thermoplastic material after thermoforming of the
orthosis (see FIG. 3B). Indeed, this narrow face is left exposed in
part to gain access to it for easy removal from the orthosis to
produce a cavity for a stem of a stopping bumper. The molding blank
is retained within the cavity of the orthosis because the wide side
43 is encased in the thermoplastic material, and this wide side 43
cannot readily fit through the opening in a cavity formed by the
exposed narrow side 42.
[0053] In addition, molding blank 40 includes a tool slot 46
configured to aid in the removal of portions of the molding blank
from the partially completed orthosis, plus a grind line indicator
48 and a drill hole 50. The grind line indicator 48 and drill hole
50 aid in formation of the orthosis.
[0054] The molding blank 40 can be used in accordance with methods
of the invention to make an orthosis having a cavity for a bumper
stem and having a bumper rest. A method of forming an orthosis 20
in accordance with the invention is depicted in FIGS. 5A through
5H. These figures also show various aspects of components used to
form the orthosis 20, plus intermediate elements of the orthosis,
and aspects of the finished orthosis. Referring now to FIG. 5A, the
molding blank 40 is adhered to a foot model 52 of a patient being
outfitted for the orthosis. Generally the foot model is encased in
a stocking, onto which the molding blank 40 is glued. The narrow
side 42 of the molding blank 40 is placed against the stocking.
Thus, the tool slot 46 and grind line 48, for example, are pressed
against the sock and not generally visible. The molding blank is
preferably adhered to the foot model using a releasable adhesive,
such as a rubber cement material. However, in other implementations
this molding blank can be physically held in place, such as by hook
and loop fasteners, and can be integrally formed with the molding
blank. In such implementations the hook elements are typically
formed in only the portion of the molding blank that comes in
contact with the sock, and preferably only the upper portion of the
molding blank has hooks because this portion of the molding blank
is eventually discarded.
[0055] The molding blank 40 is placed on the foot mold in a
position giving consideration to the eventual site of the motion
stop. In most implementations the molding blank will be placed such
that the finished motion stop and bumper rest are both above the
back of a typical shoe worn by a person who would be wearing the
orthosis. Although the precise position can vary, it is desirable
to have the bottom of the molding blank 40 be positioned above the
bottom of the ankle joint in the orthosis. In most implementations
it is also desirable that the bottom of the molding blank be
positioned above the axis of the ankle joint in the orthosis. An
orthosis normally has the axis of the orthosis align substantially
with the axis of the patient's ankle. Thus, in most implementations
the molding blank 40 is arranged such that it is above, or even
with, the axis of the ankle joint of the orthosis and the
patient.
[0056] In some implementations the molding blank 40 can be
positioned such that it extends below the axis of the ankle joint,
although it is typically desirable to have the bottom of the
molding blank be elevated as high as possible up above the bottom
of the orthosis so as to avoid obstructing the shoe of a person
wearing the orthosis. Thus, in some implementations the bottom of
the molding blank is merely 0.25 inches above the axis of the ankle
joint of the orthosis, while in other implementations the bottom of
the molding blank is 0.50 inches or less above the axis, while in
yet other implementations the bottom is 0.75 inches or less above
the axis of the top axis of the orthosis.
[0057] Once the molding blank 40 is held in place, plastic used to
form the upper 24 and lower 26 portions of the orthosis is vacuum
formed around the molding blank 40 and around the foot mold 52. The
plastic is typically a thermoformable sheet that can be
vacuum-formed at elevated temperatures and then allowed to cool
before being removed from the mold. Upon removal of the partially
completed orthosis from the mold, the molding blank is typically
retained on the orthosis, and is actually tightly secured to the
orthosis because the configuration of the molding blank is such
that the orthosis walls partially surround the molding blank
[0058] The next step in completion of the orthosis 20 is generally
cutting the molded orthosis into its upper and lower portions.
Various saws and cutting tools are suitable for this purpose. In
general the cut should follow proximate the middle or lower portion
of the molding blank and on to the ankle joint. Here, in general,
the center of the ankle joint is below the center of the molding
blank, so the cut line across the orthosis 20 is higher in the
posterior than it is along the sides of the orthosis, as shown in
FIG. 5D. At this point the lower portion 26 of the orthosis has a
substantially complete bumper rest 32 for the stopping bumper 30,
this bumper rest 32 being formed from a combination of the retained
lower segment of the molding blank, plus the portion of the plastic
wall of the orthosis that surrounds and encapsulates much of this
lower segment. It will be appreciated that, even though the lower
portion 26 is suitable for use at this time, additional grinding
and adjustment in the lower portion 26 can be performed, such as to
smoothen the bumper rest 32, or (in some implementations) to remove
the lower segment of the molding blank so as to insert an
additional motion stop.
[0059] Once the upper and lower portions of the orthosis have been
separated from one another it is generally desirable to grind down
or cut away part of the upper portion 22 of the orthosis. As shown
in FIGS. 5E and 5F the grind line can serve as an indicator of how
much of the molding blank should be removed in order to properly
place a motion stop in the cavity formed by the molding blank.
[0060] Referring now to FIG. 5G, a screwdriver or other tool can be
used to force the top of the molding blank out of the top portion
of the orthosis. This is done, for example, by using a straight
blade of the screwdriver to apply pressure into the slot 46 formed
in the molding blank. After the top of the molding blank is
removed, a stopping bumper 30 can be inserted into the exposed
cavity, as shown in FIG. 5H.
[0061] Referring briefly now to FIG. 7, it will be appreciated that
molding blanks made in accordance with the invention can also be
configured so that both ends will be removed from the orthosis,
typically so as to allow two stopping bumpers to be installed. FIG.
7 shows molding blank 40a with two tool slots 46A, each
corresponding to a separate half of the molding blank that can be
removed after cutting the upper and lower portions of the orthosis
apart.
[0062] In reference now to FIGS. 6A and 6B, various additional
aspects of the motion stop are shown. The bumper head is normally
larger than the bumper stem, having a much larger cross sectional
area. Thus, the bumper head often overlaps the top of the stem, at
least on three quarters of the perimeter of the stem. The bumper
head also normally overlaps the bumper stem by a distance
corresponding closely to the thickness of the wall of the orthosis.
The benefit of this selection is that the head then corresponds
substantially to the perimeter of the bumper rest. For example, in
some implementations the bumper head overlaps the stem on at least
three sides by a distance within 20 percent of the average
thickness of the wall forming the cavity of the orthosis, while in
other implementations this overlap is within 10 percent, and yet in
other implementations this overlap is within 40 percent of the
average thickness of the wall forming the cavity in the
orthosis.
[0063] In general the stem of the bumper stop is configured to be
at least partially exposed on the inside of an orthosis when the
stem is installed in the orthosis. For example, the stem can be
configured such that it fits into a cavity surrounding less than
330 degrees of perimeter of the stem, wherein the degrees are
calculated from the approximate center of the stem. In other
implementations the stem is configured such that it fits into a
cavity surrounding less than 300 degrees around the perimeter of
the stem.
[0064] Although the head and stem often have a significant overlap
on at least three quarters of their circumferences, in some
implementations the overlap of the head over the stem is
significantly less, or even zero, on the anterior side of the stop
(that portion facing against a patient and into the interior of the
orthosis. Thus, in some implementations the stop mechanism has a
stem with a surface 60 configured to face the inside of an
orthosis; and a head having a surface 62 configured to face the
inside of an orthosis, wherein the two surfaces of the stem and
head are substantially continuous or flat. In other implementations
there is some overlap 64 of the head onto the stem on the side of
the stop that is proximate the interior of the orthosis. For
example, this offset or overlap can be less than 5 millimeters,
normally less than 4 millimeters, more typically less than 3
millimeters, desirably less than 2 millimeters, and even more
desirably less than 1 millimeter.
[0065] Similarly, the stop mechanism can have a bumper head with a
horizontal cross section with an area at least 50 percent greater
than the horizontal cross section of the stem, the cross sections
taken at substantially the vertical center of each of the head and
stem. In some implementations the bumper head has a horizontal
cross section at least 100 percent greater than the horizontal
cross section of the stem, the cross sections taken at
substantially the vertical center of each of the head and stem.
[0066] Various materials are suitable for use with the present
invention to form the stopping bumper, including various plastics
and thermoplastics. However, the materials used must be able to
withstand significant repeat compressive forces without failure. In
particular, it is important that the material survive these
compressive forces so that the bumper head size can be kept as
small as possible while still promoting consistent contact between
the bumper head and bumper rest. In addition, the material must be
readily formed into the bumper stop, typically by injection
molding. A further general criteria is that the bumper head should
not be so hard as to create a loud clicking sound when the head
comes in contact with the bumper rest. Such loud sounds are common
with metallic stops, but are desirably eliminated.
[0067] In some embodiments the bumper head comprises thermoplastic
polyurethane with a Shore hardness of at least 55D according to
ASTM D 2240 (ISO 868), and in some implementations the bumper head
comprises a thermoplastic polyurethane with a Shore hardness of at
least 57D according to ASTM D 2240 (ISO 868). The amount of
deflection is also desirably reduced without sacrificing other
parameters, such as durability and quietness. In some
implementations the bumper head comprises thermoplastic
polyurethane having less than 10 percent deflection at 1500 pounds
per square inch of compressive load according to ASTM D575, or
having less than 15 percent deflection at 1500 pounds per square
inch of compressive load according to ASTM D575. Alternatively, in
some implementations the thermoplastic polyurethane used to produce
the stopping bumper has less than 20 percent deflection at 1500
pounds per square inch of compressive load according to ASTM D575.
The bumper head may comprise thermoplastic polyurethane having less
than 10 percent deflection at 1000 pounds per square inch of
compressive load according to ASTM D575.
[0068] In certain implementations the bumper head comprises a
polyester-based polyurethane having a flexural modulus of less than
50,000 pounds per square inch at a temperature of 23 degrees
Celsius using ASTM D790 (ISO 178), more typically less than 40,000
pounds per square inch, and even more typically less than 37,000
pounds per square inch. Similarly, the bumper head typically
comprises a polyurethane having a flexural modulus of greater than
15,000 pounds per square inch at a temperature of 23 degrees
Celsius using ASTM D790 (ISO 178), and more commonly greater than
20,000 pounds per square inch. Thus, in certain embodiments the
bumper head comprises a polyester-based polyurethane having a
flexural modulus of less than from 25,000 to 30,000 pounds per
square inch at a temperature of 23 degrees Celsius using ASTM D790
(ISO 178).
[0069] Specific suitable compositions used to form the stopping
bumper include, for example, mixtures of Texin.TM. 255 and
Texin.TM. 260 thermoplastic polyurethanes manufactured by Bayer and
available from Bay State Polymer Distribution of Westlake, Ohio.
Generally such compositions can contain at least 40 percent of each
Texin.TM. polyurethane. In certain implementations the composition
contains from 40 to 60 percent Texin.TM. 255 and from 40 to 60
percent Texin.TM. 260. In alternative implementations the
composition contains from 50 to 70 percent Texin.TM. 255 and from
30 to 50 percent Texin.TM. 260. In yet other implementations the
composition contains approximately 60 percent Texin.TM. 255 and 40
percent Texin.TM. 260.
[0070] The invention is further directed to a kit for forming an
adjustable stop for an ankle-foot orthosis, the kit comprising a
plurality of bumpers, each bumper having a head and a stem, the
head and stem of each bumper forming an interface angle between an
interior surface of the head and an interior surface of the stem.
In addition, the plurality of bumpers can have multiple different
head thicknesses, wherein the interface angle alpha between the
interior surfaces is generally less for shorter heads than for
thicker heads. Using a greater interface angle in the taller heads
assures that they will properly seat on the stop bumper at the same
location as shorter heads.
[0071] In general, motion stops made in accordance with the
invention comprise a single removable bumper that comes in contact
with a bumper rest that is not removable. However, in certain
embodiments it is possible to use two removable bumpers configured
to contact one another at a bumping interface without the use of a
non-removable bumper rest. These dual-bumper implementations are
particularly useful for applications where a patient wishes to have
different stops for different activities. For example, a single
bumper can be used by day to allow some plantar flexion, but two
bumpers can be used at night to promote gastroc stretch.
[0072] The invention also includes methods of providing medical
treatment using the improved ankle-foot orthosis. In general, one
method of using the orthosis is to provide an ankle-foot orthosis
having two cavities configured for receiving stems of a bumper
stop, inserting a first bumper stop in the a first of the two
cavities for a first period of time, inserting a second bumper stop
into either the first or second of the two cavities for a second
period of time, and repeating the final steps at regular intervals.
This method can be used, for example, to promote gastroc stretch by
having larger bumper stops, or two bumper stops, placed in the
orthosis at night, while removing one or both of the stops (or
replacing them with smaller stops) during the day.
[0073] The present invention should not be considered limited to
the particular examples described above, but rather should be
understood to cover all aspects of the invention as fairly set out
in the attached claims. Various modifications, equivalent
processes, as well as numerous structures to which the present
invention may be applicable will be readily apparent to those of
skill in the art to which the present invention is directed upon
review of the instant specification.
* * * * *