Abstract:
An ankle brace comprising a base of flexible material shaped to wrap around the sides of a foot and ankle and underneath a portion of the foot, with a support strap for protecting the anterior talofibular ligament. The two ends of the support strap are fixed to the base at or near the forward edges of the base. The strap is not otherwise fixed to the base underneath the sole of the foot, allowing the strap to move freely under the foot to conform to the particular size and shape of the foot of a particular wearer. The ankle brace features a symmetric construction which allows the ankle brace to be worn on either the left or the right foot, simplifying manufacturing and inventory management.

Description:
FIELD OF THE INVENTION 
   This invention relates generally to the field of articles worn by persons to reduce the likelihood, severity, or exacerbation of injury to the body, and more specifically to the field of braces worn on the ankle. 
   BACKGROUND OF THE INVENTION 
   The ankle joint is one of the most frequently used joints in the body, as it is required for any activity that involves walking or running. The ankle joint connects the lower leg and the foot of a person, providing a pivot point that allows the foot to rotate relative to the lower leg. Together the lower leg, ankle joint, and foot make up a complex system that must be sturdy yet flexible in order to bear a person&#39;s weight while providing freedom of movement. 
   During ambulation, and especially during strenuous sports such as football, basketball, tennis, or soccer, quick changes in direction or uneven playing surfaces can cause the ankle to move beyond its normal range of motion, resulting in a sprained ankle. A sprained ankle may be painful, and can make sports less enjoyable, reduce athletic performance, and adversely affect day to day activities. Further, once an ankle joint has been injured, the injury is more likely to recur. For these reasons, there has long been motivation to find ways to protect the ankle without restricting freedom of motion, to prevent injuries and to protect the ankle during recovery from a previous injury. 
   The ankle joint itself is comprised of a bone structure held together by ligaments. The bone structure of the ankle consists of seven tarsal bones, including the talus, calcaneus (heel bone), and navicular bones. The talus is the bone which lies adjacent to the lower ends of the tibia and fibula (the two lower leg bones). 
   A single triangular shaped ligament, the deltoid ligament, holds together the medial (inside) portion of the ankle joint, joining the tibia, talus, calcaneus, and navicular bones. Because of its size, the deltoid ligament is strong and relatively resistant to sprain injuries. 
   Four major ligaments, named for the bones they join together and their relative positions, hold together the lateral (outside) portion of the ankle joint. The anterior inferior tibiofibular ligament, located at the top of the ankle joint, joins the tibia and fibula. The anterior and posterior talofibular ligaments, located at the front and rear of the ankle joint respectively, join the talus and the fibula. The calcaneofibular ligament, located at the rear of the ankle joint, joins the calcaneus to the fibula. Most ankle sprains involve these ligaments on the lateral portion of the ankle joint. 
   The ligaments and bone structure which comprise the ankle joint determine the four basic ways that the foot can move relative to the lower leg. Dorsiflexion is when the toes are drawn toward the tibia (shin), as would occur when leaning forward. Plantar flexion is when the toes are pointed away from the tibia, as would occur when standing on tiptoes. Inversion is when the foot turns inwards, and eversion is when the foot rotates outwards. 
   Sprains may occur in any ligament in the ankle, but most sprains involve two particular ligaments on the outside of the ankle, the anterior talofibular ligament, and to a lesser extent, the calcaneofibular ligament. When an ankle sprain occurs, the anterior talofibular ligament is usually the first to be injured, followed by injury to the calcaneofibular ligament. For this reason, a sprained ankle usually involves injury to the anterior talofibular ligament or to both the anterior talofibular and the calcaneofibular ligaments, but a sprained ankle usually does not involve injury to the calcaneofibular ligament alone. 
   Many ankle sprains are the result of inversion, where the foot is rotated inward, which stretches the anterior talofibular ligament beyond its elastic limit. Injury to the anterior talofibular ligament is especially likely when the foot is plantar flexed and then undergoes forcible inversion. When the foot is at maximum plantar flexion, when the toes are pointed downward as far as possible, the anterior talofibular ligament is pulled taut. When the anterior talofibular ligament is taut, that ligament cannot stretch any further and any subsequent forcible inversion may cause that ligament to be strained, or partially or completely torn. Such forcible inversion might occur, for example, when an athlete jumps in the air and then lands on their own inverted foot or on an uneven surface, such as a hole, another player, or some other obstacle. 
   Ankle braces have been used for many years, in a variety of specific embodiments directed to particular applications, including protection of the anterior talofibular ligament. However, prior ankle braces designed to protect the anterior talofibular ligament have been made to fit either the right foot or the left foot, but not both. Thus, an ankle brace designed to protect the anterior talofibular ligament which could be worn on either the left or right foot would be desirable, to simplify inventory management and reduce costs. 
   SUMMARY OF THE INVENTION 
   The present invention features an ankle brace comprising a base of flexible material shaped to wrap around the sides of a foot and ankle and underneath a portion of the foot, with a support strap for protecting the anterior talofibular ligament. The two ends of the support strap are fixed to the base at or near the forward edges of the base, and the support strap is not otherwise fixed to the base. 
   An ankle brace according to the invention features a symmetric construction such that the ankle brace may be worn on either the left or the right foot. This feature reduces the number of different products which must be manufactured and maintained in inventory, compared to other ankle braces which can be worn on only the left or the right foot. 
   An ankle brace according to the present invention features an anterior talofibular ligament support strap which is not secured to the base of the brace beneath the foot. This feature allows the strap to move freely under the foot, so that the support strap can conform to the particular size and shape of the foot of a particular wearer. This feature provides a better fit to a particular wearer, compared to other ankle braces which include an anterior talofibular ligament support strap which is secured to the base of the brace beneath the sole of the foot. 
   Further objects, features, and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
       FIG. 1  is a side view of an ankle brace according to the invention installed on a foot; 
       FIG. 2  is a rear view of an ankle brace according to the invention installed on a foot; 
       FIG. 3  is a front view of an ankle brace according to the invention laid out flat, with the tongue and laces removed to show the internal construction; 
       FIG. 4  is a rear view of an ankle brace according to the invention laid out flat, with the tongue and laces removed to show the internal construction. 
       FIG. 5  is a front view of an ankle brace according to the invention, with the tongue and laces removed to show the internal construction; 
       FIG. 6  is a cross-sectional view of the ankle brace of  FIG. 3  taken along the line  6 — 6  thereof; 
       FIG. 7  is a cross-sectional view of the ankle brace of  FIG. 3  taken along the line  7 — 7  thereof; and 
       FIG. 8  is a side view of a resilient stay member made of flattened springs. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With reference to the drawings,  FIG. 1  is a side view of a preferred embodiment of an ankle brace in accordance with the invention, indicated generally at  10  in  FIG. 1 . The foot has a toe region  11  that extends out from an opening in the front of the ankle brace  10 , and a heel region  12  that extends out from a opening in the rear of the ankle brace. The lower leg  13  of the person extends out from an opening at the top of the ankle brace. The brace  10  generally surrounds the ankle  14  of the person. 
   The ankle brace  10  is comprised of a base, indicated generally at  15 , and a tongue  16 , which are shaped generally to wrap about the foot and ankle of a person. The base  15  of the ankle brace  10  may be fastened about the foot using a plurality of eyelets  17  and a shoelace  18  tied in a knot  19 . Although eyelets  17  and shoelace  18  are used in the preferred embodiment, other means such as straps or hook and loop material of the type that adheres when pressed together may be used. 
   As best shown in  FIG. 2 , the base  15  of the ankle brace  10  has a first side  20  and a second side  21 . The first side  20  of the base  15  has a rear edge  22 , and this rear edge  22  has an upper portion  24  and a middle portion  26 . The second side  21  of the base has a rear edge  23 , and this rear edge  23  has an upper portion  25  and a middle portion  27 . 
   As best shown in  FIG. 4 , the first side  20  of the base  15  has a forward edge  28 , and the second side  21  of the base  15  has a forward edge  29 . Eyelets  17  may be arranged along these forward edges. The shoelace  18  may be passed through the eyelets  17 , placed under tension, and tied into a knot  27 , in order to draw the first side forward edge  28  and the second side forward edge  29  together. The spacing of the eyelets  17  may be varied so that the tension of the ankle brace is greatest in the vicinity of the ankle, although this is not required. 
   As best shown in  FIGS. 2 and 3 , the ankle brace preferably has an upper rear panel  32  having a first end  33  and a second end  34 . The first end  33  and the second end  34  of the upper rear panel  32  are attached, for example using stitching  38 , to the upper portions  24  and  25 , respectively, of the rear edges of the first and second sides of the base. The upper rear panel  32  is preferably formed of elastic sheet material which stretches in both horizontal and vertical directions, although this is not required. 
   As best shown in  FIGS. 2 and 3 , the ankle brace preferably has a middle rear panel  35  having a first end  36  and a second end  37 . The first end  36  and the second end  37  of the middle rear panel  35  are attached, for example using stitching  38 , to the middle portions  26  and  27 , respectively, of the rear edges of the first and second sides of the base. The middle rear panel  35  is preferably formed of directionally elastic sheet material which stretches in the horizontal direction but is relatively inelastic in the vertical direction, although this is not required. The upper rear panel  32  and the middle rear panel  35  may be secured to each other, for example using stitching  38 , although this is not required. 
   As perhaps best shown in  FIGS. 3 and 4 , the first side  20  and the second side  21  of the base  15  are generally symmetric, such that the ankle brace  10  can be worn on either the left or right foot. Edge binding  40  may be secured, preferably using stitching  41 , to cover the edges of the base  17  and the tongue  18 , although this is not necessary. 
   Although the first side  25  and second side  26  of the base  17  may be formed of a single layer of sheet material, they are preferably formed of multiple layers of sheet materials which are secured together, for example using stitches  41 , although this is not required. As illustrated in  FIGS. 6 and 7 , an inside layer  42  and an outside layer  44  may be provided. The inside layer  42  may be chosen to have a soft surface since it may be in contact with the skin of the wearer. The outer layer material  44  may be chosen to be resistant to tearing, stains, and moisture, since it forms the outside surface of the ankle brace. Some portions of the base of the brace may also include a center layer (not shown) which may be chosen to be relatively rigid to provide structural integrity to those portions of the base of the ankle brace, although this is not required. 
   Although the base  15  may be made as a single piece, in a preferred embodiment the first side  20  and the second side  21  of the base  15  are made as separate pieces. In a preferred embodiment, an outside bottom edge attachment member  45  and an inside bottom edge attachment member  46  (shown in  FIGS. 7 and 8 ) are provided to join the first side  20  and the second side  21  of the base  15 , preferably using stitching  47 . 
   One or more resilient support means  50  may be provided on each side of the base of the brace, although this is not required. As best shown in  FIG. 4 , the resilient support means  50  are preferably comprised of a resilient stay member  51  located in an elongate pocket  52  formed between the outside layer  44  and the inside layer  42  of the base  15 , preferably by stitching  53 . Alternatively, if a center layer is provided, the elongate pocket  52  may be formed between the outside layer  44  and the center layer, or between the inside layer  42  and the center layer. The resilient stay member  51  may be formed of a pair of interleaved helical springs made of stainless steel that have been flattened, as shown in  FIG. 8 , or other flexible material of conventional construction commonly used in various types of braces. 
   In a preferred embodiment, two elongate pockets  52 , each containing a resilient stay member  51 , are located on each side of the brace, for a total of four resilient support means  50 . As best shown in  FIG. 1 , a preferred embodiment includes one resilient support means  50  located behind the ankle, approximately vertical in orientation and roughly parallel to the rear edge of the base, and a second resilient support means  50  located forward of the ankle, running approximately vertically from a point above the ankle and then curving below the ankle. 
     FIGS. 3–7  best illustrate the construction of the sole portion  60  of the base of a preferred embodiment of an ankle brace according to the invention. As best shown in  FIG. 4 , the sole portion  60  corresponds generally to the area of the base bounded by forward edge  61 , rear edge  62 , and stitches  65  on each side of the base. The sole portion  60  has an inside surface  63  and an outside surface  64 . 
   As best shown in  FIGS. 3 and 5 , an ankle brace according to the invention includes a support strap  70  having a first end  71  and a second end  72 . The first end  71  of the support strap  70  may be attached near the forward edge  28  of the first side  20  of the base  15 , and the second end  72  of the support strap  70  may be attached near the forward edge  29  of the second side  21  of the base  15 , preferably using stitches  76 . In addition to or instead of stitches  76 , the first end  71  of the support strap  70  may also be attached to the forward edge  28  of the first side  20  of the base  15 , and the second end  72  of the support strap  70  may also be attached to the forward edge  29  of the second side  21  of the base  15  using stitches  41  which are used to secure the edge binding  40  to the edges of the base, although this is not required. In a preferred embodiment, the support strap  70  is unconnected to the base  15  at any point within the sole portion  60  of the base  15 . 
   As best shown in  FIGS. 3 ,  5 ,  6  and  7 , an elongate sole strap  73 , having a first end  74  and a second end  75 , may be provided, although this is not required. The elongate sole strap  73  may be made of any sheet material having an appropriate strength and texture. The first end  74  of the elongate sole strap  73  may be attached to the forward edge  61  of the sole portion  60  of the base  15 , and the second end  75  of the elongate sole strap  73  may be attached to the rear edge  62  of the sole portion  60  of the base  15 , preferably using stitches  47 . The elongate sole strap  73  is preferably otherwise unconnected to the base  15 . 
   Thus it can be seen that the present invention provides an ankle brace which can be worn on either the left or right foot, and which is self-adjusting to fit the particular size and shape of the foot of the wearer. While the foregoing description contains many specificities, these should not be construed as limitations on the scope of the invention, but rather as an exemplification of one or more preferred embodiments thereof. Many other variations are possible. 
   For example, although a preferred embodiment of an ankle brace according to the invention includes a support strap with ends secured along a line near the forward edges of the sides of the base  15  using stitches  76 , the ends of the support strap may be attached to other points at or near the forward edges of the sides of the base. Instead of using stitches, other means could be used to secure the ends of the support strap, such as glue, thermal bonding, or other means known in the art. 
   Instead of permanently securing the ends of the support strap, detachable attachment means such as hook and loop material of the type which adheres when pressed together could be provided on the support strap and along the inside of the base, to allow the support strap to be detachably attached to the base. Instead of or in addition to hook and loop material, the ends of the support strap could be provided with holes at a plurality of points near the ends of the support strap, and the shoelace  18  could be passed through a selected set of those holes in the support strap and through the eyelets  17 . 
   There may be more than one elongated side pocket  72  containing a resilient stay member  74  on each side, and the elongated side pocket  72  may be openable at one end to allow removal of the resilient stay member or replacement of the resilient stay member with a different resilient stay member having different resiliency to adjust the amount of support provided. 
   Although shoelace and eyelets are used in a preferred embodiment to fasten the ankle brace around the foot and ankle. This could be done in other ways. Straps bearing hook and loop material of the type that adheres when pressed together could be used, with or without reversing loops, instead of or in combination with shoelace and eyelets. A greater or lesser number of straps, or eyelets could be used. An adjustable size closure assembly could be used, for example as set forth in U.S. Pat. No. 5,814,002, instead of or in combination with straps bearing hook and loop material, or shoelace and eyelets. 
   It is understood that the invention is not confined to the embodiments set forth herein as illustrative, but embraces all such forms thereof as come within the scope of the following claims.