Custom-Fitted Ankle Splint

This invention relates to a custom-fitted ankle splint.

The invention has particular application in the orthopedic medical field, where ankle sprains or fractures are often supported and immobilized with a splint or brace so that the patient can continue to walk while the injury heals. One typical such injury is a sprain of the anterior talofibular ligament at the interior margin of the lateral malleolus. In such cases, it is essential to splint the ankle in such a way as to stabilize the ankle against eversion and inversion while permitting dorsiflexion and planoflexion necessary for normal walking and therapeutic exercise. It is also desirable for the splint to be sufficiently compact to fit within a conventional shoe. This facilitates sufficient use of the injured ankle during healing so that muscle atrophy is avoided or minimized.

The invention takes advantage of polymer chemistry to permit quick and easy molding of a splint to the ankle. Shock attenuation is increased since the custom fit provides spreads contact between the splint and the ankle over a wider surface area. Similarly, the close, custom fit is in distinct contrast to so called "one size fits all" braces or splints wherein a rigid outer shell provides support, and a relatively thick cushioning pad, for example, an inflatable bladder, must be utilized to fill the voids created between the "one sized" rigid shell and the foot, ankle and lower leg.

Therefore, in the particular embodiment of the invention disclosed in this application, the splint will accommodate a wide range of sizes and can be fitted to either the right or left ankle. Thus, a much reduced inventory of splints is required. This feature also substantially reduces design and manufacturing costs, and promotes use through ease of fitting. The custom-fit of the splint permits easy removal for bathing, dressing or adjustment, and easy and mistake-proof replacement even by children.

Prior art ankle splints include numerous types of splints and braces which typically include a soft component to place near the skin and a hard, shell-like preformed outer cover having a shape approximating a "normal" ankle. The soft component, for example, fiber padding, foam or an air bladder, is intended not only to provide a cushion, but also to accommodate itself to the varying configurations of differing sized and shaped body parts. For this reason, the cushioned part is substantially greater in thickness than required merely to provide the required amount of shock attenuation and protection from the rigid substrate. Such devices are sufficiently `generic` in size and shape that they usually are required to be held in place by straps or bands.

Other prior art ankle braces include pads which are constructed of thermosetting materials which are heated and then formed to the body while heated. These products require a source of heat, and are susceptible to either over-or-underheating. In addition, body heat itself can soften or increase the flexibility of the pad, thereby decreasing the effectiveness of the protection offered by the pad.

Applicant's prior U.S. Pat. No. 5,637,077 provides a solution to some of the problems described above, but is a unitary structure which has definite forward and rearward sides. Also, because the opposing sides of the splint are integrally-formed to each other by means of a unitary heel support member, lengthwise adjustment of the splint by shortening or lengthening the heel support is not possible.

The present invention permits quick and easy application of an ankle splint to a body part in such a way as to achieve a true custom fit. The moisture curable resin system used results in a very rigid ankle splint which holds the shape of the molded splint to a very high degree. No heat is required, and a source of water is the only additional material necessary to achieve a cure. Atmospheric moisture alone will cure the splint into its hardened position in a relatively short period of time, but in practice the resin in or on the splint will typically be activated by dipping in water and then removing the excess by rolling the splint in a towel immediately before application.

Therefore, it is an object of the invention to provide a custom-moldable ankle splint.

It is another object of the invention to provide an ankle splint which can be molded to an ankle to stabilize the ankle against eversion and inversion while permitting dorsiflexion and planoflexion necessary for normal walking and therapeutic exercise.

It is another object of the invention to provide an ankle splint which can be custom-fitted to a particular patient.

It is another object of the invention to provide an ankle splint having a shape prior to forming which permits the splint to be formed onto either the left or the right ankle.

It is another object of the invention to provide an ankle splint which hardens in the presence of moisture to form a very rigid but very lightweight splint.

It is another object of the invention to provide an ankle splint which can be worn without the need for the splint to be held into place by straps or belts.

It is another object of the invention to provide an ankle splint which can be worn inside a shoe.

It is another object of the invention to provide a ankle splint which is stored in a moisture-proof pouch until ready for application to the ankle.

It is another object of the invention to provide an ankle splint which provides two splint segments which are releasably and adjustably attached together to form a splint.

It is another object of the invention to provide an ankle splint which is custom-molded to a patient's ankle in such a way that it can be initially held in place with an elastic bandage to reduce edema on the front of the foot, and thereafter held in place with straps during later stages of healing.

It is another object of the invention to provide an ankle splint which includes reinforced cushioning and protection for the ankle bones of the patient.

These and other objects of the present invention are achieved in the preferred embodiments disclosed below by providing an ankle splint product including an ankle splint for being custom-formed to the shape of an ankle while flexible and upon hardening providing a rigid, supporting custom fit. The ankle splint product includes an outer container formed of moisture-impervious material and first and second flexible ankle splint segments positioned in the container in substantially moisture-free conditions and sealed therein against entry of moisture until use. Each of the first and second ankle splint segments includes an elongate substrate, a reactive system impregnated into or coated onto the substrate, the system remaining stable when maintained in substantially moisture-free conditions and hardening upon exposure to moisture to form a rigid, self supporting structure, an elongate, flexible protective pad positioned on one side of the substrate along its length to provide a cushioning barrier between the substrate and the skin of a patient when the ankle splint is in use, and an elongate outer cover covering the substrate on the side opposite the protective pad. The substrate, protective pad and outer cover are connected together into a unitary structure for being molded while flexible to an aspect of the ankle. A flexible cushion insert has a first major surface overlying the protective pad and an opposing second major surface adapted for residing adjacent an ankle bone of the patient. The cushion insert cooperates with the protective pad to further protect and cushion the ankle of the patient when the ankle splint is in use.

According to one preferred embodiment of the invention, the cushion insert is generally U-shaped to define an open central area for accommodating the ankle bone of the patient.

According to another preferred embodiment of the invention, attachment means are provided on the first major surface of the cushion insert for attaching the cushion insert to the ankle splint segment.

According to yet another preferred embodiment of the invention, the attachment means includes a pressure-sensitive adhesive.

According to yet another preferred embodiment of the invention, the cushion insert is formed of between 0.25 and 0.50 inch thick foam.

According to one preferred embodiment of the invention, the first and second attachment members include first and second mating patches of hook-and-loop material.

According to another preferred embodiment of the invention, the first and second patches of hook and loop material are attached to one end of respective first and second splint segments with sewing stitches.

According to yet another preferred embodiment of the invention, the container is fabricated of an aluminum foil laminate having an outer tear resistant layer, a central aluminum foil layer and an inner heat sealable plastic layer.

Preferably, the substrate includes a plurality of knitted or woven fabric layers and the protective pad includes a foam material.

According to yet another preferred embodiment of the invention, the foam material is chosen from the group consisting of open or closed cell EVA or polyurethane.

According to yet another preferred embodiment of the invention, the elongate outer cover is formed of a synthetic, hydrophobic fabric.

According to yet another preferred embodiment of the invention, the fabric of the outer cover is chosen from the group consisting of woven, knitted or non-woven fabric.

According to yet another preferred embodiment of the invention, the reactive system includes a blended polyisocyanate, polyol, catalyst and stabilizer.

Preferably, the protective padding, substrate and outer cover are sandwiched together in overlying layers and joined together around their respective peripheral edges by sewing stitches to form a unitary structure.

According to yet another preferred embodiment of the invention, the protective pad and the substrate are of substantially equal thickness.

According to yet another preferred embodiment of the invention, the protective pad is between 4 and 6 mm thick and the substrate is between 4 and 6 mm thick.

According to yet another preferred embodiment of the invention, the first and second splint segments have the same peripheral shape.

According to yet another preferred embodiment of the invention, the first and second splint segments have same peripheral shape and are symmetrical along a centerline extending the length of the substrate.

According to yet another preferred embodiment of the invention, the first and second splint segments have same peripheral shape, are symmetrical along a centerline extending the length of the substrate, and have tapered upper and lower ends.

In another embodiment, an ankle splint segment is provided for being custom-formed to the shape of an ankle while flexible and upon hardening providing a rigid, supporting custom fit. The ankle splint segment includes an elongate substrate, a reactive system impregnated into or coated onto the substrate, the system remaining stable when maintained in substantially moisture-free conditions and hardening upon exposure to moisture to form a rigid, self supporting structure, and an elongate, flexible protective pad positioned on one side of the substrate along its length to provide a cushioning barrier between the substrate and the skin of a patient when the ankle splint is in use. An elongate outer cover covers the substrate only on the side of the substrate opposite the protective pad. The substrate, protective pad and outer cover are adapted for being molded while flexible to one of the lateral or medial aspect of the ankle, and are further adapted for being releasably and adjustably attached to a like splint segment molded to the other of the lateral or medial aspect of the ankle to collectively define an ankle splint. A flexible cushion insert has a first major surface overlying the protective pad and an opposing second major surface adapted for residing adjacent an ankle bone of the patient. The cushion insert cooperates with the protective pad to further protect and cushion the ankle of the patient when the ankle splint is in use.

According to one preferred embodiment of the invention, the substrate includes a plurality of knitted, woven or non-woven layers.

According to yet another preferred embodiment of the invention, the protective pad includes a foam material.

According to yet another preferred embodiment of the invention, the foam material is chosen from the group consisting of open or closed cell EVA or polyurethane.

According to yet another preferred embodiment of the invention, the elongate outer cover is formed of a synthetic, hydrophobic fabric.

According to yet another preferred embodiment of the invention, the fabric of the outer cover is chosen from the group consisting of woven, knitted or non-woven fabric.

Preferably, the reactive system includes a blended polyisocyanate, polyol, catalyst and stabilizer.

According to yet another preferred embodiment of the invention, the protective padding, substrate and outer cover are sandwiched together in overlying layers and joined together around their respective peripheral edges by sewing stitches to form a unitary structure.

According to yet another preferred embodiment of the invention, the protective pad and the substrate are of substantially equal thickness.

According to yet another preferred embodiment of the invention, the protective pad is between 4 and 6 mm thick and the substrate is between 4 and 6 mm thick.

According to yet another preferred embodiment of the invention, the splint segment is symmetrical along a centerline extending the length of the substrate.

According to yet another preferred embodiment of the invention, the splint segment is symmetrical along a centerline extending the length of the substrate, and has tapered upper and lower ends.

In yet another embodiment, a flexible, ankle bone cushion insert is provided for use in combination with an ankle splint, and is adapted for residing adjacent an ankle bone of a patient to cushion and protect the ankle of the patient when the splint is in use. The ankle bone cushion insert includes a base adapted for residing adjacent a lower portion of the ankle bone. First and second, opposing, spaced extensions are integrally-formed with the base and adapted for residing on opposite sides of the ankle bone. The base and extensions cooperate to define an open central area for accommodating placement of the cushion insert adjacent the ankle bone.

According to one preferred embodiment of the invention, a pressure-sensitive adhesive coating is provided for removably attaching the insert to the ankle splint.

According to another preferred embodiment of the invention, the base and extensions are formed of a foam material.

Some of the objects of the invention have been set forth above. Other objects and advantages of the invention will appear as the description proceeds when taken in conjunction with the following drawings, in which:

FIG. 1 illustrates the ankle splint product and removal of the ankle splint from the protective pouch;

FIG. 2 is a perspective view showing an ankle splint segment of the ankle splint product according to an embodiment of the invention;

FIG. 3 is a perspective view of the ankle splint segment of FIG. 2, with parts broken away for clarity;

FIG. 4 illustrates that each ankle splint segment is wetted in water before application;

FIG. 5 is a perspective view illustrating application of two joined ankle splint segments to the ankle;

FIG. 6 is a perspective view illustrating from the rear the ankle splint in place on the ankle;

FIG. 7 is a side elevation of the ankle splint in place on the ankle;

FIG. 8 is a front elevation of the ankle splint in correct position on the ankle;

FIG. 9 is a perspective view showing that the ankle splint is preferably wrapped to hold it in place during curing and during wear;

FIG. 10 is a perspective view, with parts broken away for clarity, of the ankle splint being worn under a sock;

FIG. 11 is a perspective view showing that the ankle splint may be held in place with straps during curing and during wear;

FIG. 12 is a perspective view of an ankle splint according to a modified embodiment of the invention with one of the splint segments folded down to show the attachment of the cushion insert to the protective pad;

FIG. 13 is an elevational view of the cushion insert; and

FIG. 14 is an elevational view of the ankle splint, in use, and showing the cushion insert and ankle bone of the patient in phantom.

Referring now specifically to the drawings, an ankle splint product according to a preferred embodiment of the invention is illustrated broadly at reference numeral 10. A sealed, moisture-impervious foil and plastic laminated pouch or container 11 is fabricated of a aluminum foil laminate having an outer tear resistant layer, a central aluminum foil layer and an inner heat sealable plastic layer. Container 11 is opened with scissors or a knife, and an ankle splint 12 according to an embodiment of the invention is removed.

Ankle splint 12 is formed from first and second separate splint segments 13 and 14, as is shown in FIG. 2. Either of the splint segments 13 or 14 may be formed to the lateral or medial aspect of the ankle and lower leg. This interchangeability reduces manufacturing expense, inventory expense and simplifies application and replacement on the ankle after removal.

While it is preferable to place a splint segment 13 and 14 into a single container 11, each individual splint segment 13 and 14 may be placed in a separate container 11. This would allow, for example, replacement of one of the splint segments 13 or 14 while continuing to use the previously molded splint segment.

Referring now to FIG. 3, ankle splint segment 13 is illustrated and described more specifically. Ankle splint segment 13 includes a multilayer substrate 16 formed of, for example, six layers of woven fiberglass fabric 16A-F overlaid in registration with each other to form a laminated structure.

Other fabric material and constructions, such as knitted polypropylene, can also be used for the substrate fabric. The fiberglass fabric layers 16A-F of the substrate 16 are impregnated or coated with a moisture-curable resin such as polyisocyanate as described in full in the present applicant's U.S. Pat. No. 4,770,299. This reactive system remains stable when maintained in substantially moisture-free conditions, such as in the moisture-impervious pouch 11, but hardens upon exposure to sufficient moisture to form a rigid, self-supporting structure. A typical formulation of the reactive system is set forth in the following table:

A complete discussion of the parameters of the reactive system, the manner of production and the variables which apply are found in U.S. Pat No. 4,411,262.

The polyisocyanate resin remains in a viscous, liquid unhardened state so long as the resin is not exposed to moisture. This permits the fiberglass layers 16A-F to remain flexible and moldable so long as the resin is not exposed to moisture, and for a relatively short period of time after exposure to moisture. The curing time can be controlled to some extent by the quantity and temperature of the water to which the resin is exposed. For example, exposure to water by dipping will result in quite rapid curing, while merely allowing the resin to be exposed to air will cause long curing times proportional to the amount of moisture in the air to which it is exposed.

Resin coated or impregnated fiberglass layers 16A-F are covered with a foam protective pad 19, which may be a single thickness or a laminated structure. One preferred embodiment is a 3/16 inch, six pound EVA (ethylene vinyl acetate) pad. Another embodiment may be a 3/8 inch laminated pad of a 1/8 inch outer EVA pad and a 1/4 inch outer polyethylene/polyurethane, combination open and closed cell foam. Spaced-apart ventilation holes 19A permit rapid penetration of water to the substrate 16 during wetting and curing, and permit improved air flow and cooling while being worn by the patient.

The pad 19 covers and provides cushioning between the skin and the rigid substrate 16. The pad 19 is flexible enough to bend easily with the other components of the ankle splint segment 13 during fitting and curing. The pad 19 extends the entire length of the ankle splint segment 13. The pad 19 and the substrate 16 are approximately the same thickness--on the order of about 4-6 mm.

A fabric outer cover 20, such as a woven polyester fabric, covers the side of the substrate 16 opposite the side covered by the foam pad 19. The fabric cover is sewn with, for example, an overedge or serging seam 21 directly to the edges of the foam pad 19 enclosing the substrate 16.

A patch 22 of male or female hook-and-loop material is sewn onto one end of the splint segment 13 defined as the bottom or heel end. As is shown in FIG. 3, loops 23 on one face of the patch 22 are positioned on the same side of the splint segment 13 as the pad 19.

As is shown in FIG. 2, the structure and shape of the splint segment 14 is essentially identical to that of the splint segment 13, this being noted throughout this application by reference numerals in prime notation. The only difference in splint segments 13 and 14 is a patch 24 of hook-and-loop material complementary to patch 22 is sewn onto one end of the splint segment 14. As is shown, the hooks 25 on one side of the patch 24 are positioned on the same side of the splint segment 14 as the fabric cover 20'. Because of this arrangement, when the side of the splint segments 13 and 14 having the pads 19 and 19', respectively, are placed against opposing medial and lateral aspects of the ankle, the loops 23 face upwardly and the hooks 25 face downwardly, thereby allowing attachment of the two splint segments 13 and 14 together to collectively form the splint 12. The patches 22 and 24 when attached form a heel stirrup 27 which provides some padding and protection to the heel while stabilizing the lower portion of the splint 12.

Referring now to FIGS. 4-11, preparation and application of the ankle splint 12 is illustrated. In FIG. 4, the ankle splint segments 13 and 14 have just been removed from the protective container 11 and the splint segment 13 is dipped in water to activate the moisture-curable resin described above. Immediately thereafter the splint segment 14 is likewise dipped in water.

As shown in FIG. 5, the wetted and still flexible ankle splint segments 13 and 14 are attached together by marrying the hook-and-loop patches 22 and 24 to form the heel stirrup 27 and the splint 12. The splint 12 is immediately placed on the foot by positioning the heel of the patient directly onto the heel stirrup 27. Preferably, the splint segments 13 and 14 are each symmetrical along opposite sides of their longitudinal axis, so there is no defined forward or rearward side edge. The splint segments 13 and 14 of the splint 12 are then flexed upwardly along the lateral and medial aspects of the lower leg, as indicated by arrows 17 and 18 in FIG. 6, so that the splint segments 13 and 14 are positioned as shown. See also FIGS. 7 and 8. Note that ankle splint 12 is usable on either the right or left foot.

The ankle splint 12 is held in place so that as the curing takes place the exact conformation of the ankle and leg is transferred to the ankle splint 12. The ankle splint 12 will harden within a matter of minutes, and will permanently retain the conformation in which it was held during curing. The fit is close and exact. With no voids to fill or accommodate as the patient moves about, complete and even protection to the body is provided. The pressure exerted by the splint 12 is very evenly spread over the maximum practical surface area, thereby reducing the possibility of chafing, rubbing or blistering at points of uneven pressure.

Note, also, that the heel stirrup 27 remains flexible after the splint segments 13 and 14 cure and harden. Removal and replacement of the splint 12 is facilitated since the custom-formed splint segments 13 and 14 easily fold away from the ankle, using the heel stirrup 27 as a hinge.

As is shown in FIGS. 6 and 8, a properly applied ankle splint 12 splints the medial and lateral aspects of the ankle and foot with minimal coverage of the front or rear of the foot or leg. Thus, eversion and inversion of the foot is prevented while permitting substantially unrestricted dorsiflexion and planoflexion necessary for normal walking and therapeutic exercise, and an enhanced ability to place the foot into a normal shoe. Typically, a relatively soft shoe, such as an athletic shoe will accommodate the ankle splint 12 easily, it being necessary only to loosen the laces to permit added width to the shoe.

As is shown in FIG. 9, the ankle splint 12 may be held in place during curing by a wrapping, such as a conventional elastic medical bandage 30. Such a bandage may also be worn during treatment as a way of maintaining a close fit of the ankle splint 12 against the foot and leg. This has been found to reduce edema in the front of the foot during the early stages of recovery, when pressure applied by the splint 12 to the sides of the ankle might otherwise force fluid to the front of the foot. A sock 35 may also be used to hold the ankle splint 12 in place during hardening, as is shown in FIG. 10.

Straps such as elastic straps or straps with hook and loop fasteners such as straps 40 and 41 may be used to hold the ankle splint 12 in place during treatment, as is shown in FIG. 11. These straps preferably may be separate elements, like straps 40 and 41, or may be sewn onto the ankle splint 12 during manufacture.

As noted above, the heel stirrup 27 remains flexible, so some form of support is required to hold the splint 12 in supporting position against the ankle. The relative thinness and compactness of the splint 12 permits a wide variety of supports, including even a high-topped shoe or boot.

In one preferred embodiment suitable for children and adults of small stature, each ankle splint segment 13 or 14 has an overall length of 30 cm, an overall width of 9 cm at a point one-half of the distance between the upper and lower ends and taper to a width of 5 cm at each end. The heel stirrup is preferably 5 cm wide and each of the hook-and-loop patches 22 and 24 are 7 cm long.

In another preferred embodiment suitable for adults of medium and large stature, each ankle splint segment 13 or 14 has an overall length of 35 cm, an overall width of 10 cm at a point one-half of the distance between the upper and lower ends and taper to a width of 5 cm at each end. The heel stirrup is preferably 5 cm wide and each of the hook-and-loop patches 22 and 24 are 7 cm long. The ends of the splint segments 13 and 14 may be rounded rather than tapered as shown in the drawings and described herein. In addition, other forms of cushion padding, such as air bladders, gel-filled bladders or other types of foam or matrix products may be used. The approximate thickness of the body of the ankle splint 12 in both sizes is 8 mm, and of the hook-and-loop patches 22 and 24--2 mm.

Referring now to FIGS. 12-14, an ankle splint 100 according to the invention further includes one or two separately attached foam cushion inserts 110 positioned, respectively, to reside adjacent one or both of the medial and lateral ankle bones "B" of the patient to further protect and cushion the ankle when the splint 100 is being used. The medial ankle bone "B" is shown in FIG. 12. The ankle splint 100 is formed of splint segments 111 and 112 constructed as described above with reference to splint segments 13 and 14. The reference herein to medial and lateral "ankle bones" means the lower prominences of the tibia and fibula, respectively, also known as the "malleoluses."

As shown in FIG. 12, the cushion insert 110 has an inside major surface 110A which overlies the protective pad 116 of the splint segment 112 and includes a pressure-sensitive adhesive coating 118. After molding the splint segment 112 to the ankle, as previously described, the molded segment 112 is folded away from the ankle and the insert 110 placed in an area of the pad 116 residing adjacent the ankle bone "B" of the patient when the splint 100 is being used. Light application of pressure to an outside major surface 110B of the insert 110 activates the pressure-sensitive adhesive coating 118 which holds the insert 110 in place as the splint segment 112 is returned to its in-use position against the ankle. The adhesive coating 118 allows convenient removal and repositioning of the insert 110 for custom placement to suit the individual patient, and replacement of the insert 110 when worn. The outside major surface 110B of the insert 110 is adapted to reside against the skin of the patient.

As best shown in FIGS. 13 and 14, the cushion insert 110 is generally U-shaped with an open central area defined by a base 121 and opposing integrally-formed extensions 122 and 123. The term "U-shaped" is defined broadly herein to include, for example, structure which is generally V-shaped or horseshoe-shaped. When the splint 100 is in use, the base 121 of the insert 110 resides directly adjacent a lower portion of the ankle bone "B" with the extensions positioned on opposite sides of the ankle bone "B". The open central area provides space for accommodating the ankle bone "B" and for reducing pressure applied by the splint segments 111 and 112. According to one embodiment, the cushion insert 110 is formed of flexible, 1/4-inch thick polycushion foam with an overall height of 3.28 inches and an overall width of 2.54 inches. One cushion insert 110 is preferably used per splint segment 111 and 112 for each of the medial and lateral ankle bones of the patient.

An ankle splint is described above. Various details of the invention may be changed without departing from its scope. Furthermore, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation--the invention being defined by the claims.