Note: Descriptions are shown in the official language in which they were submitted.
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ANKLE SPLINT
Background of the Invention
This invention relates to orthopedic appliances and more specific
gaily relates to removable appliances for substantially immobilizing the ankle
joint. One of the most common orthopedic injuries is the ankle sprain. This
injury occurs when there is sudden forceful hyperinversion or hype reversion of
the ankle joint. The ligaments connecting the ankle bones (molehill) to the footare thus partially or completely torn. There is immediate pain and inability to
bear weight on the affected limb. Swelling then occurs at the site of the injury,
generally in proportion to its severity.
Treatment objectives are to relieve pain and to promote healing of
the torn fibers of the involved ligaments. These objectives are accomplished by
immobilization of the affected joint in a neutral position and reduction of the
distortion of the joint due to swelling. Elevation compression and cold
applications, initially, followed by alternating cold and warm baths later in the
course of treatment, are valuable adjuncts.
Immobilization is accomplished by a variety of methods. One
method is to wrap an elastic bandage around the foot and ankle, occasionally
incorporating U-shaped fell pads that are placed so that the soft tissue
surrounding the molehills is compressed to minimize swelling. Crutches are used
for partial weight bearing for several days or weeks. The elastic bandage does
not afford the complete immobilization needed for solid healing of severely tornligaments and its use is associated with a higher incidence of reinjury. Daily
activities are limited by the associated use of crutches.
A second method of immobilization is the application of a plaster
cast with the addition of a walking heel or boot. Plaster casts permit firm
immobilization, but require a two- or three-day period of walking with crutches,using extreme care not to bear weight on the cast because to do so causes it to
soften, rendering it useless Since these casts usually stay on for at least two
weeks before they are removed and/or replaced, they cause itching and
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sometimes dermatitis secondary -to perspiration and bacterial over-
growth. As tissue swelling about the ankle decreases and muscle
atrophy occurs in the calf, the cast becomes loose and uncomfort-
able. Thus, the extremity should be recanted, entailing more
physician time and expense and another period of crutch usage.
Another method of treatment involves the application to
the ankle of various preformed apparatus, such as braces and non-
plaster casts. In spite of some apparent advantages, none of
these appliances has ever gained popular acceptance. It is
suspected that one reason for the lack of acceptance is the failure
of the appliance to account for the bilaterality of the extreme-
ties, i.e., left and right sides. When one observes the foot and
ankle it is apparent that there are marked differences between the
medial and lateral aspects. First of all, -the medial side is
larger. Secondly, the first metatarsophalangeal joint is located
anteriorly to the fifth metatarsophalangeal joint and is more
prominent. Thirdly, there is an arch located on the medial aspect
of the foot but none on the lateral aspect. Fourthly, the medial
molehills is located anteriorly and superiorly to the lateral
molehills. The foregoing anatomical facts would seem to preclude
a comfortable fit by any snug fitting cast or apparatus that
encases the foot and ankle but does not incorporate at least some
features of bilaterality into its design.
In addition, it is noted that the prior art appliances
typically apply pressure evenly over the entire ankle without con-
side ration that -there should be less pressure over the bony prom-
inences (molehill) and greater pressure over the surrounding soft
tissue in order to reduce swelling around the torn ligaments.
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The invention provides a walking splint removably attach-
able to the lower leg and foot to substantially immobilize the
ankle joint comprising: a discrete posterior member of sub Stan-
tidally rigid material, inflexible at the ankle joint and adapted
for placement on the back of said leg, said posterior member
extending from the midpoint of the calf of said leg downwardly
around the heel of said foot and underlying the bottom of said
foot to insure a constant right angular relationship between said
leg and said foot; a discrete anterior member of substantially
rigid material adapted for placement on the front of said leg,
said anterior member extending from a point substantially at the
same height as an upper end of said posterior member, said anterior
member overlying at least a portion of said foot; a discrete
lateral member of substantially rigid material adapted for place-
mint over the lateral portion of said leg and extending to cover
the lateral molehills, said lateral member having a distal outward
flare in the portion covering the molehills and including a recess
formed in the distal portion to anatomically conform to the lateral
molehills; a discrete medial member of substantially rigid material
adapted for placement over the medial portion of said leg and
extending to cover the medial molehills, said medial molehills
being covered by a distal portion of said medial member which is
flared outwardly with respect to the remaining portion of said
medial member and including a recess formed in the distal portion
covering said molehills of a size adapted to anatomically conform
to the medial molehills; a plurality of straps vertically spaced
from one another along said posterior member, said straps being
operable to encircle said members and to tighten to apply tension
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to hold said members firmly against said leg and said foot, said
straps including a means for fastening said straps.
The splint desirably is capable of being worn comfort-
ably for two -to eight weeks, depending on the severity of the
sprain, to ensure complete ligaments healing. The splint allows
early ambulation without the use of crutches so that little time
is lost from work, school, or other activities and that incorpor-
ales a walking surface as an integral part of -the unit. The splint
is easily applied, easily removed for bathing, rest and physical
therapy and is easily reapplied, is preferably adjustable to accom-
mediate tissue swelling and muscle atrophy as well as individual
variations in anatomy and, once adjusted, stays firmly in place.
The splint can be produced for both left and right lower
extremities and can take into account the anatomical differences
between the medial and lateral aspects of the ankle joint as well
as preventing pressure directly on the molehill while applying
increased pressure over the peri-malleolar tissue to decrease
edema and thereby promote healing of torn ligaments.
A walking ankle splint is hereby presented for the treat-
mint of ankle sprain, which is designed to provide stability and immobilization of the ankle joint while said sprained ankle lima-
mints are healing. The splint includes four substantially rigid
plastic members, each lined with a compressible material. A
posterior member supports the back of the leg, extends around the
underside of the foot, and provides a walking platform with an
arch support and an antiskid undersurface. The medial and lateral
members support the respective sides of the lower leg and ankle
bones and anatomically conform to the lower leg and ankle bones.
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The anterior member supports the anterior portion of the lower
leg and upper foot. The four members are held in place encasing
the ankle joint by straps with adjustable fasteners so that the
members are held snugly in place. The straps allow removal or
adjustment and reapplication of the splint members. Preferably,
the straps are anchored within the posterior member and have an
attached rectangular ring that acts as a buckle and also prevents
circumferential slippage of the straps. Preferably, the straps
are secured to the side and anterior components by attached,
easily removable fastening means such as hook-and-loop fasteners
of the type sold under the trademark VELCRO to permit multidirec-
tonal adjustment of the splint members. In the preferred embody-
mint, the splint members are made in a plurality of sizes and for
both the left and right lower extremities.
The ankle splint of the present invention will be better
understood by those of ordinary skill and others upon reading the
ensuing specification when taken in conjunction with the accom-
paying drawings wherein:
FIGURE 1 is an exploded isometric view of one embodiment
of a splint made in accordance with the principles of the present
invention ready to be applied to the left lower extremity;
FIGURE 2 is an isometric view of the splint of FIGURE 1
secured in place on the left lower extremity;
FIGURE 3 is a side elevation Al view of the splint of
FIGURE 1 in
I
place on the let lower extremity from the medial aspect;
FIGURE 4 is a front elevation Al view of the splint of FIGURE 1 in
place on the left lower extremity;
Figure 5 is a side elevation Al view of the splint of FIGURE 1 in
5 place on the left lower extremity from the lateral aspect;
INURE PA is a front elevation Al view of the medial member of
the splint of FIGURE 1 for the left lower extremity;
INURE 6B is a side elevation Al view of the medial member of the
splint of FIGURE l;
FIGURE PA is a front elevation Al view of the lateral member of
the splint of FIGURE 1 for the left lower extremity;
FIGURE I is a side elevation Al view of the lateral member of the
splint of FIGURE l;
FIGURE is a plan view of the splint of FIGURE 1 for the left
15 lower extremity in the assembled condition; and
FUZZIER 9 is a detailed view in expanded scale of a portion of the
posterior member of the splint of FIGURE 1 for the left lower extremity.
Detailed Description of the Preferred Embodiment
FAKER 1 illustrates a preferred embodiment of an ankle splint
20 made in accordance with the principles of the present invention. The splint
comprises a posterior member 10, an anterior member 12, a medial member I
and a lateral member 16. The members are formed so that they encompass and
hold firm the lower let and foot of the patient to substantially immobilize the
ankle joint during healing of an ankle sprain. The splint, in its assembled state,
25 positioned on a lower leg 13 and foot 15 of a person is shown in FIGURES 2, 3, 4
and 5.
The posterior member 10 is the largest component ox the splint.
The posterior member is generally L-shaped and includes a vertical portion 18
that supports the posterior aspect of the leg from approximately the mid calf of30 the leg downwardly to the heel. The posterior member wraps around the heel toprovide an underlying platform portion 20 upon which the foot of the patient
rests. The vertical portion I is typically comprised of an outer plastic shell what
is approximately 0.3 centimeters thick at the proximal (upper) end and graduallybecomes thicker (approximately 1.0 centimeters) over the Achilles tendon aspect
35 where more support is needed. The vertical portion 18 and the platform
portion 20 of the posterior member 10 form substantially a right ankle. The
posterior member has a heel recess formed therein to accommodate the heel of
the wearer. The heel recess is typically approximately 7.5 centimeters at its
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widest diameter for an adult splint. unless specified all further dimensions will
be given for a size of splint that will fit an average adult male.) Typically the
plastic foot platform portion 20 is approximately 2.5 centimeters thick except
for the medial aspect in which it becomes gradually thicker under the arch of the
5 foot to create an arch support portion 22. The maximum thickness of the arch
support portion 22 is approximately 5.0 centimeters.
The undersurface 23 of the foot platform portion 20 of the
posterior member 10 preferably has a plurality of spaced grooves formed therein
to increase the traction of the surface and minimize the possibility of slipping10 while walking. The grooves are best seen in FIGURES 3 and 5. Alternatively, aseparate walking surface ox rubber or some other antiskid material can be
affixed to the ~mderside of the posterior member. The posterior member has
integrally formed in it four slots 24, 26, 28 and 30 for the purpose of retaining
four straps 32 that encircle the members to hold them in their correct positions15 about the lower extremity. The slots 24 and 26 are formed in the vertical
portion 18 of the posterior member while the slot 30 is formed in the foot
platform portion 20 approximately under the center of the foot The fourth
slot 28 is formed in a portion of the posterior member behind the heel of the
wearer at approximately the place where the vertical portion 18 and foot
20 platform portion 20 meet. Typically, the slots have inside dimensions of
approximately 5.0 centimeters by 0.5 centimeters to snugly contain a portion of
the fastener straps 32 which pass through the slots. The entire inner surface ofthe posterior member 10 is lined with a layer 11 of compressible foam. The foam
conforms more comfortably to the immobilized lower extremity than the hard
25 plastic shell of the posterior member. The compressed foam in the preferred
embodiment described herein is approximately 1.0 centimeters thick.
Referring to FIGURES PA and 6B, a preferred embodiment of the
medial member 14 is shown. The medial member 14 consists of an outer shell 34
of summered plastic material and an inner layer 36 of compressible foam
30 material. As viewed from the medial aspect as shown in FIGURE 6B, the medial
member 14 has a substantially rectangular, elongated shape with a rounded distalportion 38 adapted to overlie the rnalleolus. The distal portion I has a slight
anterior projection to conform to the adjacent posterior and anterior members
when the splint is in place on the lower extremity and foot of the patient. In
35 FIGURE PA, it can be seen that the medial member has an outward flare of the
distal portion 38 with respect to the remaining elongate portion of the medial
member of approximately 70 degrees to anatomically conform to the shape of
the lower extremity.
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Two well-known physiological principles stout that prolonged
pressure over bony prominences may result in pressure sores and that edema
(excess tissue fluid) retards healing. In keeping with these principles there is a
recessed area 40 formed in the distal portion 30 of the medial member to
5 correspond and conform to the anatomic configuration of the medial molehills
thereby decreasing pressure over the bony prominence of the medial molehills
and concurrently allowing greater pressure to be applied over the edematous
peri-malleolar tissues. In the illustrated embodiment, intended for use by an
average sized adult male, the recessed area 40 is approximately 4.0 centimeters
10 at the widest anteroposterior diameter on the compressed foam material aspect.
FIGURES PA and 7B illustrate a preferred embodiment of the
lateral member 16 that comprises an outer shell 42 of semi-rigid plastic material
and an inner layer 44 of compressible foam material. In both medial and lateral
members typically, the outer shell is approximately 0.3 centimeters thick while
15 the compressible foam layer is approximately 1.0 centimeters thick. As viewed from the lateral aspect shown in FIGURE 7B, the lateral member 16 has a
generally rectangular shape with a rounded distal portion 46 that overlies the
lateral molehills when the splint is in place on the lower extremity of the
patient. For an average adult male the lateral member 16 is typically
20 approximately 30 centimeters long and 4.5 centimeters wide in the central
portion.
As viewed from the anterior aspect shown in FIGURE PA, the distal
portion 46 is flared outwardly approximately 20 degrees with respect to the
elongate portion of the lateral member to conform to the anatomical
25 configuration of the lateral aspect of the lower extremity. In conformance with
the previously stated physiological principles relating to edema and pressure
sores, there is a recessed area 48 formed in the distal portion 45 of the lateral
member to correspond and conform to the anatomic configuration of the lateral
molehills, thereby decreasing pressure over the bony prominence of the lateral
30 molehills and allowing greater pressure to be applied over the peri-malleolartissues surrounding the molehills, thereby diminishing the possibility of edema.Again, for an average adult male the recessed area 48 is approximately 3.0
centimeters at the widest anteroposterior diameter on the compressed foam
material aspect. Note that the recessed portion 48 of the lateral member 16 is
35 slightly smaller than the recessed portion 40 of the medial member 14. This
again takes into consider lion the anatomical makeup of the typical lower
extremity.
As can be seen in FIGURES 2 through 5, the anterior member 12
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covers the anterior portion of the lower leg and a portion of the dorsum of the
foot. It is positioned between the medial and lateral members 14 and 16. The
anterior member consists of a plastic outer shell 50 and an inner compressible
foam layer 52. The anterior member 12 is formed in such a fashion as to
conform to the anatomical configuration of the lower extremity. The proximal
(upper) portion 54 is of a height equal to the lateral, medial and posterior
members, and for a typical adult male it is approximately 7.5 centimeters at itswidest point. As the anterior member descends toward the ankle, it narrows to
accommodate the typical narrowing of the leg and, again, for a typical adult
male narrows to approximately 4.5 centimeters. The anterior member then
flares out again over the dorsum of the foot where it is formed in a convex
manner with the apex of the convexity overlying the first metatarsal bone. The
flared portion of the anterior member 12 overlies the proximal portion of the
metatarsal bones and the general anatomical conformity allows a snug fit to be
obtained between the anterior member 12 and the foot 15. The flared portion of
the anterior member stops short of covering the metatarsophalangeal joint
because wide individual anatomical disparities caused by bunions, callouses, etc.,
preclude a uniformly comfortable fit. In addition, to achieve immobilization of
the ankle, it is unnecessary to immobilize the metatarsophalangeal joints. The
anterior member 12 comprises an outer shell 51 of semi-rigid plastic material
and is lined with a layer 53 of compressible foam material.
The fastener straps 32 are used to hold the lateral, medial, anterior
and posterior members in place, securely positioned about the lower extremity.
The straps 32 are secured by passing through the previously described retainer
slots 24, 26, 28 and 30 formed in the posterior member 10. Typically, the strapsare approximately 5.0 centimeters wide and are made of a durable fabric
material. FIGURES 3, 4 and 5 show, from various views, the use of the straps 32
in holding the members securely to the lower extremity of the patient as the
splint is used to immobilize the ankle joint. Each of the fastener straps, as
viewed in FIGURE 8, wraps completely around the four members and passes
through a rectangular ring 61 affixed to a first end of the strap. The strap is
then looped back as illustrated by the arrow 58 in the opposing direction so it can
be pulled tight and the end of the strap secured to keep the splint in place.
FIGURE 9 illustrates in greater detail how the strap 32 passes through one of the
retainer slots 24 and loops through the rectangular ring 61. In the preferred
embodiment, the straps 32 are made of a loop fastener component material such
as used on combination with a hook fastener component material to form the
hook and loop fastening system such as that sold under the trade name VELCRO.
A second end of the strap has a piece of the hook fastener component affixed to
it and the second end can therefore be attached to the body of the strap when
the strap is pulled tight. Use of such hook and loop fastening means, as opposedto a simple buckle, provides for continuous adjustability range for the strap to5 conform to the wide range of sizes of patients. Therefore, patients within a
range of sizes can use the same splint and a separate customized splint does nothave to be made for each individual patient. This lowers substantially the cost
involved in the use of the ankle splint of the present invention.
The lateral, medial and anterior members each have a respective
10 strip 60, 62 and 64, respectively, of the hook component of the fastening
material affixed to approximately the midline of the longitudinal axis of each of
the respective plastic outer shells. Since the strap itself is comprised of the loop
component material of the hook and loop fastener system, the strips 60, 62, and
64 attached to the lateral, medial and anterior members will adhere to the strips
15 of material to provide multidirectional position adjustment and to assist in
holding the lateral and medial members in place vertically on the lower
extremity and, also holding the anterior member in place firmly against the
dorsum of the foot of the patient. The rectangular rings 61 are of a size large
enough to prevent their passing through the slots in the posterior member. The
20 end of the fastener straps loop through the rectangular rings and then double back and secure upon themselves by means of the hook and loop fastening
characteristics. If one considers the rings in the sense of pulleys, in accordance
with physical principles, the mechanical advantage obtained by pulling the strapagainst the ring to apply more tension in tightening the straps provides a more
25 firm fit of the splint to the leg. The make-up of the various straps 32 and
strips 60, 62 and 64 can either be hook or loop components of the fastening
system as long as the two comprise a cooperative pair to enable the strap to
adhere to the respective strips.
In the biological world, animals have bilateral extremities, one
30 extremity being the mirror image of the other. For this reason, a well fitting
glove cannot fit both hands, a well fitting shoe cannot fit both feet, and a well
designed ankle splint cannot fit both ankles. It is therefore necessary, because of
the bilaterality of the extremities, to adapt the ankle splint of the present
invention for the right or left extremity. However, the adjustability of the
35 straps and compressibility of the inner layer of foam allows a single size splint to
fit a range of sizes of lower extremities so that while a plurality of sizes of
splints must be made to fit the entire population, it is not necessary to customize
each splint to a particular patient but rather one size splint will fit a range of
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patients.
In summary, therefore, a multimembered splint for placement upon
the lower extremity and foot of a patient to immobilize the ankle joint of the
patient in the process of treatment of an ankle sprain includes four members that
5 surround the lower extremity and foot and are held in place by adjustable straps.
The members conform anatomically to the characteristics of the lower extremity
including a flare in the lateral and medial members to accommodate the natural
flare of the leg and recesses in the lateral and medial members where they fit
over the lateral and medial molehill so as to reduce pressure upon the bony
prominence of the molehill but apply greater pressure to the peri-malleolar
tissues to reduce edema and prevent pressure sores. While a preferred
embodiment of the invention is described and illustrated herein, it will be
understood by those of ordinary skill in the art and others, that several changes
can be made to the illustrated embodiment while remaining within the spirit and
15 scope of the present invention. For example, a wide variety of materials can be
used in the manufacture of the splint as long as the rigidity of the members is
maintained. Further, while hook and loop fastening straps of the Velcro type
have been described, other fastening straps are possible. The dimensions given
herein are exemplary only and are not intended to limit the scope ox the
20 invention. The invention, therefore, should be defined solely by reference to the
appended claims.
