U.S. patent application number 09/967912 was filed with the patent office on 2004-02-19 for neuropathic foot protector.
Invention is credited to Burek, Paul, Gallegos, Alvaro, Jensen, Jeffrey L., Jensen, Michael J..
Application Number | 20040031169 09/967912 |
Document ID | / |
Family ID | 25513492 |
Filed Date | 2004-02-19 |
United States Patent
Application |
20040031169 |
Kind Code |
A1 |
Jensen, Jeffrey L. ; et
al. |
February 19, 2004 |
Neuropathic foot protector
Abstract
A shoe for treating and preventing chronic foot wounds such as
ulcerations in diabetes patients. A malleable shoe upper is
attached to a sole and receives a custom-fitted orthosis produced
by imprinting the patient's plantar aspect into heat-deformable
foam or a hardening silicone. A heel of the shoe includes an
internal spring to further dampen reactive forces.
Inventors: |
Jensen, Jeffrey L.;
(Evergreen, CO) ; Jensen, Michael J.; (Littuton,
CO) ; Burek, Paul; (Contennial, CO) ;
Gallegos, Alvaro; (US) |
Correspondence
Address: |
GIBSON, DUNN & CRUTCHER LLP
Suite 4100
1801 California Street
Denver
CO
80202-2641
US
|
Family ID: |
25513492 |
Appl. No.: |
09/967912 |
Filed: |
September 28, 2001 |
Current U.S.
Class: |
36/27 ; 36/154;
36/93 |
Current CPC
Class: |
A43B 7/147 20130101;
A43B 17/02 20130101; A43B 21/30 20130101; A43B 13/189 20130101;
A43B 7/28 20130101; A43B 13/16 20130101; A43B 13/187 20130101 |
Class at
Publication: |
36/27 ; 36/93;
36/154 |
International
Class: |
A43B 007/14 |
Claims
What is claimed is:
1. A shoe adapted for the prevention or treatment of foot wounds in
a patient, comprising: a shoe upper; a sole attached to the shoe
upper, the sole including a heel with a spring therein; and an
orthotic footbed fitted into the shoe upper
2. The shoe of claim 1, wherein the orthotic footbed has an upper
surface custom-fitted to the plantar aspect of the patient's
foot.
3. The shoe of claim 2, wherein said orthotic footbed is a
heat-deformable foam material.
4. The shoe of claim 2, wherein the orthotic footbed includes a
compressible forefoot section and a less compressible rearfoot
section, and a transition section of gradually changing
compressibility.
5. The shoe of claim 2, wherein said orthotic footbed includes a
bladder filled with a hardened liquid material.
6. The shoe of claim 4, wherein said hardened liquid material is
silicone injected into the bladder in a liquid condition and
hardened with a curing agent.
7. The shoe of claim 2, wherein the upper is malleably deformed to
accommodate irregularities in the patient's foot.
8. The shoe of claim 2, wherein said spring is a coil spring having
an upper end bearing against the sole and a lower end bearing
against a bearing surface of the heel.
9. The shoe of claim 2, wherein the sole includes a rigid plate
over the heel end a compressible material at the forefoot.
10. A method for treating or preventing foot ulcers in diabetic
patients, comprising: custom fitting an orthotic footbed to the
patient's foot; placing the orthotic footbed into a shoe having a
spring-loaded heel; and allowing the patient to be ambulatory in
the shoe, whereby shearing and impact forces on the patient's foot
are partially absorbed by the orthotic footbed and the
spring-loaded heel.
11. The method of claim 10, wherein said custom-fitting step
includes selecting a footbed of a size appropriate to the patient,
the footbed being of a heat-deformable foam; heating the foam to a
predetermined deforming temperature; and planting the patient's
foot onto the foam to deform the foam surface to conform to the
patient's foot.
12. The method of claim 10, wherein said custom-fitting step
includes selecting a footbed of a size appropriate to the patient,
the footbed being a bladder with an inlet port; god injecting the
bladder through the inlet port with a liquid material; planting the
patient's foot onto the bladder to conform the bladder to the
patient's foot; and allowing the liquid material to harden.
13. The method of claim 12, wherein said liquid material includes
silicone resin and a hardening agent.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of protective
foot gear and, in particular, a foot protector for preventing or
treating foot ulcers in neuropathic patients.
BACKGROUND OF THE INVENTION
[0002] Tissue wounds are common injuries. Wounds can be internal or
external. Discontinuity in the integrity of the skin is typically
referred to as an external wound.
[0003] External wounds can be produced from external trauma, such
as impact or cutting forces. Such external trauma may be
deliberate, as in the case of an incision produced by a surgeon's
scalpel, or accidental, as in the case of scrapes and cuts produced
by common accidents. A further category of external wounds includes
chronic wounds produced in a predictable but to some extent
unavoidable manner by chronic friction pressure and inflammation,
e.g., diabetic foot ulcers, pressure ulcerations (bed sores) and
venous insufficiency ulcerations.
[0004] The formation and healing of external chronic wounds is
aggravated by vascular disease. Reductions in blood flow to a
tissue site can itself produce a wound by resulting in insufficient
tissue oxygenation or insufficient fluid drainage. Because vascular
disease is typically chronic, the resultant wounds are also
chronic.
[0005] Diabetes presents special wound complications and severity.
Approximately 19 million people have diabetes in the United States
alone, of whom a third are undiagnosed. Of the two-thirds who are
diagnosed, 90% (about 9.9 million) have Type II diabetes and 10%
(about 1.1 million) have Type I diabetes.
[0006] Diabetes patients often suffer from varying degrees of
vascular disease and sensory peripheral neuropathy; in other words,
their feet and hands tend to be insensitive. In more extreme cases,
the patient has little or no sensation in his feet. When a wound
develops in such a patient, the patient experiences no pain, and
indeed may be wholly unaware of the wound. Many of these wounds are
on pressure points on the foot. As the insensitive patient
continues to apply pressure to these wound points, as by simply
walking, the wound becomes very severe, ulcerated and perhaps
infected. The repeated trauma of ambulation contributes to the
wound formation at the outset. Vascular impairment further
compromises the healing of these wounds. It has been estimated that
there are 800,000 diabetic foot ulcer cases per year in the United
States, representing 3.5 to 7% of the diagnosed diabetes
population. The population at highest risk has sensory peripheral
neuropathy, with or without peripheral vascular disease, foot
deformities or a history of wounds.
[0007] When a foot ulcer becomes infected often the only option is
amputation to save the patient's life. These diabetic foot ulcers
result in about 67,000 foot amputations per year in the United
States alone. They account for more hospitalizations than any other
single complication of diabetes. The problem appears to be
worsening; the lower extremity amputation rate has increased each
year since 1990. About 84% of these amputations are preceded by
foot ulcers.
[0008] The significance of these cases can be measured both in
quality of life and economic indicators. Quality of life issues are
particularly important because nontraumatic ulceration can lead a
patient with diabetes through a cycle of ulceration, subsequent
infection, antibiotic treatment, hospitalization, and lower
extremity amputation with long-term therapy. This sequence of
events can produce long-term disability which burdens the family
attempting to care for this individual.
[0009] The economic effect of these cases is staggering. American
Diabetes Association statistics show that 16% of healthcare
expenditures in the United States are spent on patients with
diabetes, and that 10% of that money is spent directly related to
foot conditions. National economic statistics show an average
hospital length of stay of 19 days for infected diabetic
ulcerations. It is believed that the cost of a lower extremity
amputation averages a total of about $75,000 from the initial
presentation of the wound to a resulting amputation. If that figure
is accurate, then the annual cost of the 67,000 amputations in the
United States alone is over $5 billion. Further, the treatment cost
for the 800,000 foot ulcerations in diabetes patients, even without
amputation, averages $5,000 per year, for a total of another $4
billion.
[0010] The Vascular Advisory Board to the American Diabetes
Association has indicated that approximately one-third of the
67,000 annual amputations are unavoidable. This is mainly due to
the inability of the patient to have a revascularization procedure
performed. Compounding this, several studies have verified that
contra lateral limb amputations occur in 30% to 60% of the patients
who have undergone one lower extremity amputation. As daunting as
these figures are, however, two-thirds of the67,000 annual
amputations are considered avoidable, or over 44,000.
[0011] It has been shown that well-constructed and properly fitting
shoes are necessary to avoid foot wounds in diabetes patients,
particularly in patients with sensory peripheral neuropathy and
motor neuropathy. Fashion styles, especially for women, often
influence selection of footwear instead of considerations of
comfort and support. The purpose of the footwear from a medical
standpoint must be to provide support, foot stability, shock
absorption, and a foundation for orthoses.
[0012] Reimbursers such as Medicare acknowledge the need for
preventing foot ulcers for high-risk patients with diabetes.
Provisions currently allow for one pair of extra-depth, extra-width
shoes and three pairs of orthoses per year to be provided to
high-risk patients. Three pairs are allowed because "accommodative"
orthoses are inherently flexible and compressible by nature. This
allows for protection of potential ulcerative locations, but also
means a limited lifespan of three to four months per pair.
[0013] The tragic personal consequence and horrendous economic
implications of foot ulcers in diabetes patients has led to several
prevention and treatment modalities. Six of these are briefly
described below:
[0014] 1. Custom-made, custom-molded shoes with accommodative
full-contact orthosis fabricated from a positive cast.
Accommodative, for above-noted purposes, is defined as devices
which attempt to support the foot without changing or altering
biomechanical function. A shell requiring the use of recognized
accepted protective materials interfacing with the insensitive
foot, such as Plastozote or Poron brand materials, together with
posting materials provide the rigidity of the rear foot orthosis.
These shoes are the only medically indicated treatment for severely
deformed feet, partial foot amputees (e.g., transmetatarsal
amputation), severe foot deformity, (e.g., Charcot deformity with
midfoot collapse), severe hammertoe deformities, and severe hallux
valgus deformities. This alternative is appropriate for only 5% to
8% of patients that have foot structures mandating custom shoes and
orthoses.
[0015] 2. Extra-depth, extra-width over-the-counter shoes with
custom-molded tridensity accommodative full-contact orthosis
fabricated from a positive cast. This is the same as the orthosis
described in the preceding paragraph, but the shoes are
over-the-counter and not custom-made. The advantages are: (1)
improved appearance; (2) less expense; (3) more variety of styles;
and (4) more ready availability. The limitations are that: (1) the
shoe is not custom made; (2) it cannot fit severe deformities; and
(3) it requires external shoe modifications at times, which are
dependent upon personnel in the clinic.
[0016] This orthosis redistributes pressure throughout the entire
foot, which decreases pressure in the high-risk areas to thereby
reduce risk of ulceration. However, this orthosis is relatively
expensive and time-consuming to construct, tends to be variable in
its manufacture, is often poorly made, and the patient needs three
pair per year.
[0017] This orthosis has been used in research at the Diabetic Foot
and Wound Center in Denver, Colo. Over 450 ulcerations were healed
and subsequently placed in extra-depth or extra-width shoes with
custom-molded tri-density fabricated orthoses, fabricated from a
positive cast. The result was a 24.9% recurrence rate. For purposes
of this study, "recurrence" is defined as reulceration at the same
site. Previous studies have shown an 86% recurrence rate if these
techniques were not utilized. In general, this orthosis is
recognized as the Gold Standard in preventing diabetic foot
pressure ulcers and is appropriate for the high-risk patients with
diabetes who do not qualify for alternative #1 above.
[0018] 3. Extra-depth shoes with accommodative non-full-contact
fabricated inlay. A shoe manufacturer, such as Apex Ambulators,
often provides this type of orthosis. These shoes are very
inexpensive, and they can accommodate minor dorsal deformities such
as hammertoes or first metatarsocuneiform exostoses. The
disadvantage is that they are not clinically effective in reducing
plantar surface pressures where 95% of the wounds occur. In
essence, this is not an option for the high-risk diabetic foot as
previously described. This is commonly the type of device that is
dispensed by nationally known orthopedic providers charging $400 to
$600 for shoes and inlays.
[0019] 4. Extra-depth shoes with nonaccommodative, non-full-contact
inlays. This type of appliance is often provided by a shoe
manufacturer such as New Balance and PW Minor companies. These
shoes have the advantage of being inexpensive and they can be used
with minor dorsal deformities. The disadvantages are that the
inlays are not accommodative, nor are they full contact. Also
patients can buy and fit themselves. This is not a good situation,
as patients with diabetes traditionally fit the shoes too tight,
due to the loss of foot sensation, and develop further
complications.
[0020] 5. Non-extra-depth over-the-counter shoes. The only
advantage of these kind of shoes is that there is increased
selection, color, and style. These shoes (1) do not have the
required depth currently mandated by the Medicare Therapeutic Shoe
Bill to accommodate a three-eighths of an inch orthosis once the
factory inlay is removed; (2) have a non-oblique toe box; (3) have
a lack of medical and lateral rear foot stability; (4) will not
accommodate dorsal deformities; and (5) will not accept an
accommodative, prefabricated, or custom orthosis due to lack of
depth of the shoe. These are commonly the type of shoes that
patients with new ulcers are wearing when they first seek care for
their foot problem. Medically this is not an acceptable option.
[0021] 6. Open-toe, open-heel shoe gear. The open toe offers the
advantage of extra room for dorsal deformities. The main
disadvantage is that this type of shoe exposes the foot to trauma
by allowing outside entrance of foreign objects such as rocks,
coins, pins, etc. In addition, this shoe has no accommodative
plantar protection, and it allows excessive lateral shearing
forces.
SUMMARY OF THE INVENTION
[0022] A goal of the present invention is to prevent as many lower
extremity amputations as possible by preventing the initial ulcer
from occurring. This addresses a crucial need in the chain of
events prior to amputation, protecting the high-risk foot before an
ulcer occurs. The invention can be made readily available to
patients without the limitations of time and money inherent in
present alternatives.
[0023] The present invention is a one-unit protective shoe and
custom-fitted orthosis system. The shoe, orthosis and foot function
as one unit because ground reactive forces are addressed by the
shoe and shearing forces are addressed by the orthosis. Current
alternatives can only be piece-mealed together, thereby
compromising the effectiveness of the intended purpose of wound
prevention. This addresses the cost, time, and variability
shortcomings of current alternatives. The ease of application and
use of this invention can increase use, thus reducing the number of
foot wounds, the number of lower extremity amputations, and
healthcare costs.
[0024] Twenty percent of patients with diagnosed diabetes--a total
of 2.2 million individuals--are deemed at high risk for developing
neuropathic foot ulcers. The use of the present invention to avoid
wounds would result in system-wide cost-savings by preventing many
wounds entirely, thereby eliminating the cost of subsequent
treatments such as hospitalization, surgical intervention, and
rehabilitation. If using the present invention results in only a 5%
(2,233) reduction of amputations deemed "avoidable" with proper
intervention (44,666), there would be a $167,497,500.00 savings in
healthcare spending (assuming an average cost of $75,000 per
amputation). With diabetes accounting for 16% of the healthcare
dollars in the USA, and foot-related complications representing 10%
of the total cost of care for diabetes, this treatment modality
would readily be embraced both by governmental agencies and managed
care organizations.
[0025] The present invention couples a customized protective
orthosis with appropriate shoe gear. It has three main
components:
[0026] 1) An orthosis that:
[0027] a. Protects bony prominences on the plantar foot,
[0028] b. Is custom and full-contact,
[0029] c. Maintains protection over extended period of time without
compromise,
[0030] d. Is quick and easy to produce.
[0031] 2) A shoe that has the characteristics of being:
[0032] a. Extra-depth,
[0033] b. Extra-width,
[0034] c. Deep toe-box,
[0035] d. Negative heel,
[0036] e. Malleable to allow for stretching around bone
prominences,
[0037] f. Comparable in weight to New Balance and PW Minor
shoes,
[0038] g. Protective to bony prominence on the distal toes; dorsal,
medial and lateral foot; and the Achilles tendon region posterior
through appropriate materials and seam construction,
[0039] h. Shock absorbing heel.
[0040] 3) A means to merge the orthosis and shoe resulting in
excellent protection of the insensate foot.
[0041] This present invention includes shoe upper which is
malleable to be conformed to irregularities in a patient's foot.
The shoe upper is attached to a sole which includes an integral
heel spring in a foam surround. Fitted inside the shoe is the
orthosis. the orthosis is designed to be custom molded to the
patient's foot, using a heat deformable closed foam material or a
quick-setting silicone in a rubber bladder. The integrated unit
allows sheer forces to be minimized by the interface between the
custom molded orthosis and the patient's foot, and allows
ambulation impact forces to be absorbed by the heel spring.
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] FIG. 1 is an exploded view of the present invention, showing
a shoe upper, an orthosis, a sole and a heel.
[0043] FIG. 2 shows the process of imprinting the plantar aspect of
a patient's foot onto an orthosis in accordance with one preferred
embodiment of the invention.
[0044] FIG. 3 shows the process of injecting silicone resin and
curing agent into a bladder orthosis in accordance with another
preferred embodiment of the invention.
[0045] FIG. 4 shows the invention with a cut-away section showing
the inside of a heel.
DETAILED DESCRIPTION OF THE INVENTION
[0046] The invention comprises two main elements: an orthosis and a
shoe. An external exploded view of a preferred embodiment of the
invention 10 is shown in FIG. 1. The invention 10 includes a shoe
upper 42, and orthosis 14, a sole 50, and a heel 48.
[0047] First described is the orthosis 12 which serves as a footbed
inside the shoe. The purpose of the orthosis 12 is to reduce
shearing stress by absorbing a portion of the patient's body weight
and allowing equal weight distribution throughout the contact area.
The orthosis 12 is shaped generally as a footbed to fit securely
and removably inside the device 10 between the sole 50 upper
surface and the patient's foot.
[0048] The bottom of a human foot is normally not planar.
Therefore, the top surface of the orthosis 12 similarly is
non-planar; rather, it roughly conforms to the plantar aspect of a
human foot, with recessed areas 14 and 16 to receive the heel and
an elevated area 18 corresponding to the arch. The orthosis 12 is
made in several sizes to accommodate the several foot sizes of
patients. Further, the edges may be trimmed to match foot sizes
more exactly or to fit better within the shoe 11.
[0049] The material for the orthosis 12 should be moldable to
conform closely to the bottom of an individual patient's foot. In
one embodiment, the orthosis of composed of ethylene-vinyl-acetate
("EVA") in a closed cell foam. EVA is already used in other medical
applications, including orthoses, and is of a proven durability, is
biologically inert, and is not known to produce any medical side
effects such as rashes or allergies. In contrast, other open and
closed cell foams are unsuitable because they overcompress and
break down, which ultimately compromise their ability to absorb
compressive or impact forces.
[0050] EVA is commercially available in several densities and
thicknesses. The most preferable appear to be 2 or 3 pound
densities and 3/8 or 1/2 inch thicknesses. The foam orthosis 12 has
a soft, biocompatible woven cloth material 22 on the outer surface
to facilitate putting on and removing shoes.
[0051] Patients often tend to develop ulcerations at the forefoot.
One embodiment of the invention addresses this specific wound site
by using softer foam at the forefoot and harder foam at the rear.
The boundary between the softer foam at the forefoot and harder
foam at the rear is a gradual transition. The gradual transition is
accomplished by extending the wedge-shaped portion 82 of the softer
foam 84 over a wedge-shaped portion 86 of the harder foam 88, as
shown in FIG. 5.
[0052] When EVA is used in conjunction with a shoe heel spring
(described below), the patient's weight is distributed between the
EVA and the heel spring in about a 40/60 division. The EVA foam
thus avoids life-shortening over-compression of the orthosis 12.
The allocation of shearing forces between the EVA foam orthosis 12
and the heel spring caused by normal gait lessens the force to the
plantar aspect and orthosis 12.
[0053] The EVA orthosis 12 is custom-molded to the patient as
follows: Heat is applied to the orthosis 12; then the patient
applies his or her foot to the orthosis 12 as shown in FIG. 2 to
mirror the plantar aspect of the patient's foot in the custom
orthosis 12. This can be done safely because the foam is heated to
only about 160.degree. F. (71.degree. C.), and the patient wears an
insulated sock while the foot is in contact with the heated EVA
foam pad. The duration of contact between the foot and the orthosis
12 during this molding process depends in part on the patient's
weight. By exactly matching the foam orthosis 12 to the contours of
the bottom of the patient's foot, the most efficient weight
distribution is achieved.
[0054] The molding process described above has long been utilized
commercially in custom-fitted ski boots. The patient fitting
process of 30 minutes is relatively quick compared to current
systems that can take up to several days. This type of EVA material
has the ability to be formed with relatively low heat and more
quickly than other materials.
[0055] The orthosis 12 may alternatively be a silicone-filled
bladder 30 as shown in FIG. 3. The bladder is filled with silicone
that hardens to a durometer hardness of 50A on the Shore A hardness
scale. The hardness is similar in density to a soft and semi-hard
rubber. A silicone that has a hardness of 50A is desirable because
it is soft enough to be comfortable to the patient while hard
enough to offer adequate foot stability, thereby reducing friction
and shearing forces.
[0056] The silicone is injected into a pre-formed bladder envelope
using a syringe-like device 34 with an attached mixing chamber 35
prior to the nozzle outlet. The nozzle 37 is designed to fit the
bladder inlet port 36. One part of the silicone is the resin, and
the other part is the curing agent. When the two parts are mixed,
they will solidify into a semi-hard material with a durometer
hardness of 50A. After the bladder is filled, the inlet port 36 is
sealed using a heat-sealer apparatus (not shown). The inlet port 36
is the same thickness as the bladder and therefore does not
interfere with the fit in the shoe or cause any irritation to the
patient's foot.
[0057] The foot bladder orthosis 12 is filled with this highly
viscous, 2-part silicone formulation, which conforms to the
contours of the bottom of the foot. To effect the molding, the
patient applies pressure on the bladder orthosis 12 to create the
form of the plantar aspect of the foot. The patient may be either
standing or sitting while the foot is making contact with the
orthosis 12 bladder to allow for a semi-weightbearing position of
the foot. More silicone can be injected into the bladder while the
patient is applying pressure. After approximately 15 minutes, the
bladder takes on a permanent form even after the foot is removed
from the silicone gel-filled orthosis. Total cure time is 8 hours
before the orthosis can be placed in the shoe. This customizes the
silicone gel orthosis, resulting in an even distribution of
pressure as the patient applies weight with each step. Similar gel
pack systems have been used commercially in ski boots and
recreational hiking boots. It should be noted that other methods
for curing the silicone may also be utilized, such as ultraviolet
light.
[0058] The thickness of the silicone-filled orthosis 12 should be
from 3/8" to 1/2". The foot bladder envelope material is
0.010"-0.015" thick polyurethane film. One side of bladder is a
polyester felt 38, which is in contact with the patient's foot
(with sock applied). The bladders are die cut and RF sealed (via
radio frequency energy) to contain the silicone gel. The pack
envelope is with triple-sealed seams to ensure that the pack does
not burst even with a heavier person. The pressure on the seams is
minimal since the silicone is cured to a semi-hard consistency, and
most of the weight is transferred to the shoe spring described
below. Several foot sizes can be produced to meet the patient foot
sizes. The orthosis 12 is a major component that ensures the
efficacy of the device and should be a custom medical device.
[0059] Although the 8-hour cure time is a disadvantage to this
system, it is a reliable method of creating a full-contact
orthosis, and is an improvement over existing technologies that
usually take days to create a custom, hand-made orthosis. The
silicone gel is not adversely affected by temperature changes
because it is a stable material once it is in the cured state. The
silicone filled bladder becomes the orthosis 12 when assembled into
the modular walking shoe. Like the EVA foam orthosis 12, the
silicone filled bladder orthosis 12 is used in tandem with the heel
spring described below, which absorbs most of the patient's
weight.
[0060] The invention features three main non-traditional shoe
components to meet the shoe requirements for high-risk patients
with diabetes which are designed to accomplish the following
objectives:
[0061] 1) Protect the entire foot utilizing a two-component
system;
[0062] 2) Redistribute pressure away from bony prominences;
[0063] 3) Provide a stable platform to receive an accommodative
orthosis;
[0064] 4) Provide cushioning that reduces ground-reactive forces to
the orthosis and foot;
[0065] 5) Reduce shearing within the shoe cavity;
[0066] 6) Maintain stability over a long period of time;
[0067] 7) Provide a protective covering for the foot;
[0068] 8) Reduce the time to properly fit patients; and
[0069] 9) Work as a unit with an accommodative orthosis.
[0070] The malleable shoe upper 42, shown in FIG. 1, is designed to
be manually altered around the foot. As such, the upper 42 can be
easily redirected away from bony prominences (particularly in the
toe area) utilizing standard shoe stretching techniques. The upper
42 is comprised of non-irritating materials with modified seams for
reduced irritation. The upper 42 can be easily stretched to
accommodate changes in the foot or shrinkage or expansion of upper
42 materials.
[0071] Located directly beneath the orthosis 12 is a sole 50. The
sole 50 includes an embedded rigid plate 44 extending from the heel
to just proximal to the metatarsal phalangeal joint as shown in
FIG. 1. The plate 44 provides a solid foundation for the orthosis
12. The orthosis, as previously noted, is designed to redistribute
pressure and protect musculoskeletal abnormalities. As such, the
orthosis 12 must be flexible. To maintain the integrity of its
shape over time the orthosis 12 must be firmly supported from below
to truly support the foot structure. The plate 44 is also critical
in distributing ground-reactive forces into the orthosis 12 and
foot. The 3/4 length plate 44 significantly redirects these forces,
proximal to and away from the high-risk bony prominences of the
forefoot.
[0072] The sole 50 also preferably includes a forefoot section 51,
which is a compressible material such as foam or soft rubber, and
provides additional absorption and dampening of reaction forces on
the forefoot.
[0073] The plate system is designed to provide a foundation for the
orthosis. The plate system is built from a nylon/plastic with
injected glass fiber (for strength). The plate is permanently
attached to the forefoot cushioning material. Neuropathic feet are
susceptible to Charcot neuroarthropathy through the possible
twisting and torque to the foot caused by uneven surfaces, rocks or
unstable ground. The supportive nature of the plate 44 prevents
twisting and/or torque of the foot. The plate 44 also serves as an
effective barrier in preventing foreign objects from penetrating
the show and ultimately the foot.
[0074] Located directly below the 3/4 length plate 44 is the heel
element 48, shown in both FIG. 1 and FIG. 4. The active component
of the heel 48 is a conical steel spring 46. The primary purpose of
the spring 46 is to reduce the overall shock to the orthosis and
foot. By reducing the rate of impact the spring effectively
curtails ground-reactive forces. By absorbing ground-reactive
forces into the shoe the impact on the orthosis 12 is decreased
thereby increasing the efficacy and durability of the orthosis 12.
The secondary purpose of the spring 46 is to provide an element of
stability to the foot by absorbing small to medium deviations in
the ground. Normal shoe cushioning devices do not have enough
cushioning to effectively absorb deviations in the ground.
[0075] The spring 46 may be sleaved in or surrounded by foam rubber
or other material to prevent stones or other external objects from
interfering with free compression and extension, and also to
improve the appearance of the device. Beneath and attached to the
spring 46 is a heel bottom 49 to form a smooth surface to contact
the floor or the ground.
[0076] The union of the orthosis 12 and the shoe should not
compromise the accommodative attributes of the orthosis 12
plantarly or the shoe dorsally, distally, medially, laterally or
posteriorly. There must be a seamless interface making the device
function as one unit. Also, the malleability and ease of stretching
of the shoe outer must not compromise the integrity of the
structure of the shoe. The orthosis 12 is the preferred embodiment
will rest in the shoe without any attachment method, as the shoe
will contain the orthosis and keep it from moving in any direction.
The design of merging the orthosis 12 to the shoe without
comprising the orthosis 12 interface with the insensate foot is
addressed by allowing the system to work as a single unit.
[0077] The shoe appears very similar in aesthetics to ordinary
shoes when assembled, except that the sole 50 and heel 48 are
obviously much thicker to accommodate the heel spring. However, the
internal design of the shoe is significantly different from an
ordinary shoe because it is "malleable" and has spring cushioning
properties. The upper of the shoe is malleable to accommodate width
of the diabetic foot with standard stretching techniques and
musculoskeletal deformities (such as bunions, hammertoes, claw
toes, mallet toes, and tailor's bunions). The upper materials and
seams are non-abrasive in nature.
[0078] The coil spring cushioning system located below the plate 44
is attached in a semi-permanent fashion to the plate system. The
spring is fabricated from tempered steel music wire and exhibits
less than 5% fatigue over a 12-month period. The spring is
encapsulated in resilient foam. The forefoot 50 (ball of the foot
area) cushioning uses 19 mm of extra soft neoprene padding, which
is encapsulated in stiffer density outside padding.
[0079] In use with patients, the first step is to mold an orthosis
12. As described in some detail above, this involves conforming the
orthosis 12 to the plantar aspect of the patient's foot. If the
orthosis 12 is of the EVA closed foam type described above, the
orthosis 12 is heated to the appropriate temperature, the patient's
foot is sleeved with a protective sock, and the foot is planted
onto the orthosis with sufficient pressure to deform the closed
cell EVA foam. The EVA foam is then allowed to set in the deformed
configuration. If the orthosis 12 is of the silicone gel type
described above, the two components of the silicone are injected
into the bladder via the bladder injection port, the patient's foot
is planted onto the bladder, to deform the bladder surface, and the
silicone is allowed to set and harden in the deformed
configuration. The orthosis 12 thus is custom-fitted to the plantar
aspect of the particular patient.
[0080] The shoe is also customized for the patient by deforming the
malleable upper. This is done in accordance with well-known and
ordinary shoe upper deformation techniques that have been used in
the shoe industry for many years. The difference in this
application is that the desired deformation is to accommodate the
type of protrusions or unusual configurations that are common to
diabetes patients or other patients using the device with foot
disorders.
[0081] The orthosis 12 is then fitted into the shoe. The shoe
comprises the malleable upper, the supporting plate, and the
spring-equipped heel. The shoe, so fitted with the customized
orthosis 12, is then worn by the patient in the usual manner.
[0082] The orthoses 12 will occasionally wear out. A new orthosis
12 can then be made for the patient in the same manner as the
original orthosis 12, and the original one is replaced in the shoe
by the new one.
* * * * *