Patent Publication Number: US-4649939-A

Title: Mid-hind foot stabilizer

Description:
RELATED APPLICATION 
     This is a continuation-in-part application of patent application Ser. No. 524,428, filed Aug. 18, 1983 now U.S. Pat. No. 4,461,288. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The present invention pertains to an apparatus for stabilizing the foot joints during exercise and, more particularly, to a stabilizer strap worn external to a shoe for stabilizing the subtalar joint during the exercise. 
     BACKGROUND OF THE INVENTION 
     During exercise, the joints of an athlete&#39;s foot are subjected to most severe shear forces. In particular, the joint between the talus bone and the calcaneus bone, which forms the subtalar joint, is the recipient of a large portion of these shear forces. Primarily, these forces are the result of shocks generated when the heel strikes the ground. These shocks are exacerbated during running, since, during the running gait, both feet simultaneously leave the ground. As the heel strikes the ground during running, an increased motion occurs in all of the foot joints, with the forces distributed thereover by hydraulic action. This hydraulic action is due to the talar bones being held together by an integral network of muscles, tendons and ligaments that allow only limited motion, thus resulting in dispersion of the forces throughout the foot. 
     Although there is only limited motion between the talar bones, a certain amount of movement is provided in order to stabilize the foot on uneven surfaces. Such movements are inversion (pronation) which is turning of the foot inward and eversion (supination) which is turning the foot outward. When the heel of the foot strikes the ground, the remainder of the foot lags such that all of the weight is supported by the calcaneus bone. Until the distal portion of the foot strikes the ground, the foot is allowed to rotate about the subtalar joint which can cause excessive pronation. Normally, an adequate pair of athletic shoes can reduce this excessive pronation by providing arch support. However, athletic shoes have a tendency to slip during exercise and do not properly stabilize the subtalar joint. Moreover, an athlete&#39;s foot often swells during exercise, thus changing the fit and support of the athletic shoe during the exercise. If the subtalar joint and the joints therearound are not continually properly stabilized, pain can result from excessive rotation about these joints. 
     In view of the above, there exists a need for a stabilizing device that minimizes movement of the subtalar joint of the foot during exercise, and which may be adjusted during exercise in order to maintain proper support at all times. 
     SUMMARY OF THE INVENTION 
     The present invention disclosed and claimed herein comprises an apparatus for stabilizing movement of the infratalar joints of the foot and includes a dorsal strap for applying a dispersive force about the dorsum of the foot and directed along the line of motion of the infratalar joint. An Achilles strap is provided for applying a dispersive force about the tendo-calcaneus proximate the attachment point thereof to the calcaneus bone and directed towards the posterior talo-calcaneal joint. A plantar strap is provided for applying a dispersive force about the sole of the foot proximate the attachment point of the plantar fascia to the calcaneus bone and directed towards the infratalar joints. The dorsal strap, Achilles strap and plantar strap reduce movement of the infratalar joints during exercise and are interconnected such that an increase of force on one of the straps distributes the force to the remaining straps. 
     In another embodiment of the present invention, the straps are interconnected on the medial side of the foot adjacent the tendon connections to the navicular bone and adjustably connected together on the lateral side of the foot. The lateral connection allows for adjustment of the length of the Achilles and dorsal straps such that the force can be distributed around the infratalar joints. By adjusting these straps, compensation can be made for swelling in the foot and also different magnitudes of force therefor. 
     In yet another embodiment of the present invention, a shoe is first disposed over the foot and the straps placed external to the shoe to secure the shoe to the foot in addition to stabilizing the infratalar joints. In this manner, the straps assist the function of the shoe in distributing the forces incurred during running. The strap can be external to the shoe or an integral part thereof. 
     In still another embodiment of the present invention, the dorsal strap is modified to include a conventional lacing system. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying Drawings in which: 
     FIG. 1 illustrates a side view of the tarsal bones and depicting the infratalar joint; 
     FIG. 2 illustrates a lateral view of the apparatus of the present invention disposed external to a shoe; 
     FIG. 3 illustrates a medial view of the apparatus of the present invention disposed external to the shoe; 
     FIG. 4 illustrates a rear view of the shoes of FIGS. 1 and 2 with the apparatus disposed thereon; 
     FIG. 5 illustrates a planar view of the inner side of the apparatus unwrapped from the shoe; 
     FIG. 6 illustrates a planar view of the other side of the strap of FIG. 4; 
     FIG. 7 illustrates a side view of an alternate embodiment of the apparatus of the present invention shown as an integral part of the shoe; 
     FIG. 8 illustrates a top view of the instep pad disposed over the dorsum of the foot and integral with the shoe; 
     FIG. 9 illustrates a planar view of a second alternative embodiment of the apparatus of the present invention; 
     FIG. 10 illustrates a lateral view of the apparatus of FIG. 9 as an integral part of the shoe; 
     FIG. 11 illustrates a medial view of the apparatus of FIG. 9 shown as an integral part of the shoe; and 
     FIG. 12 illustrates a top view of the apparatus of FIG. 9 disposed over the dorsum of the foot and integral with the shoe. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In order to fully understand the present invention, an explanation of the construction of the human foot is necessary. Referring to FIG. 1, there is illustrated a medial view of the tarsal bones of the human foot. The heel of the foot is formed with the calcaneus bone 10 which is the largest and strongest of the tarsal bones. The calcaneus 10 articulates with the talus 12 and the navicular 14. The remainder of the foot is formed by articulation between the cuneiform bones 16, which articulate with the navicular 14, the metatarsals 18 which articulate at the base thereof with the cuneiform bones 16 and at the distal end with the phalanges 20. The superior surface of the talus 12 has a broad smooth trochlear surface for articulation with the tibia. The internal surface of the talus 12 presents at its upper part a pear-shaped articular facet for articulation with the inner malleolus and the external surface presents a large triangular facet, concave from above downward for articulation with the external malleolus. 
     The head of the talus 12 articulates with the navicular and the inferior surface thereof presents two articular facets separated by a deep groove. This groove runs obliquely forward and outward, becoming gradually broader and deeper in front, and corresponds with a similar groove on the upper surface of the calcaneus 10 and forms, while articulated with the calcaneus 10, a canal, filled up by the interosseous talo-calcanean ligament. There are three facets for articulation between the talus 12 and the calcaneus 10, the posterior, middle and anterior facets. Of these articular facets, the posterior is the larger, of an oblong form and deeply concave from side to side. The anterior and middle facets are shorter and narrower of an elongated oval form, convexed longitudinally. 
     The talus 12 takes part in three joints, the supratalar joint (not shown), the infratalar joints 22 and the pretalar joint 24. The supratalar joint is the ankle joint which is the articulation of the talus 12 with the tibia and allows flexion and extension of the foot. The operation of the supratalar joint is essentially that of a hinge joint. The infratalar joints 22 permit a gliding of one bone on the other in a direction from side to side. The pretalar joint 24 permits considerable mobility and essentially consists of a rotation motion. Therefore, the infratalar joints 22 and the pretalar joints 24 provide means by which the sole of the foot may be slightly flexed and extended or carried inward (inversion or supination) and outward (eversion or pronation). During exercise, the infratalar joints 22 and the pretalar joints 24 are subject to an undue amount of stress when the heel of the foot strikes the ground. Although there are numerous ligaments that bind the tarsal bones together, excessive supination or pronation can result. This excessive supination or pronation can cause pain or discomfort to the individual due to excessive movement in the infratalar and pretalar joints. 
     Referring now to FIGS. 2, 3 and 4, there are illustrated medial, lateral and rear views of a stabilizing strap 25 in accordance with the present invention disposed external to a shoe 28. A dorsal strap 26 is disposed exterior to the shoe 28 on the dorsum of the foot. An Achilles strap 30 is disposed over the tendocalcaneus adjacent the attachment point thereof to the calcaneus bone. A plantar strap 32 is disposed under the sole of the shoe 28 proximate the attachment point of the plantar fascia to the calcaneus bone 10. One end of each of the straps 26, 30 and 32 is secured together on the medial side of the shoe 28 at a connecting point 34. The straps 26, 30 and 32 are fabricated from a cotton polyester blend webbing. In the preferred embodiment, the plantar strap 32 has a thickness that is approximately twice the thickness of the Achilles strap 30 and the dorsal strap 26 since, as will be described hereinbelow, a greater magnitude of force is imparted. to the plantar strap 32. 
     The other end of the plantar strap 32 has a length of connecting strap 36 and a length of connecting strap 38 attached thereto to a connecting point 40, the connecting straps 36 and 38 having a fixed oblique angle with respect to the center line of the plantar strap 32. The angles between each of the connecting straps 36 and 38 and the center line of the plantar strap 32 are similar to the angles between both the Achilles strap 30 and the dorsal strap 26 and the center line of the other end of the plantar strap 32. The connecting point 34 and the connecting point 40 are sewn on the ends of the plantar strap 32 to maintain all angular relationships. 
     A ring clasp 42 is connected to the free end of the connecting strap 36 and a ring clasp 44 is connected to the free end of the connecting strap 38. The ring clasp 42 is operable to receive the free end of the dorsal strap 26 and the ring clasp 44 is operable to receive the free end of the Achilles strap 30. The free ends of the straps 26 and 30 are turned back over and connected to the surfaces thereof after tensioning thereof, as will be described hereinbelow. 
     Referring now to FIGS. 5 and 6, there are illustrated two views of both sides of the stabilizing strap 25 removed from the shoe 28 and depicted as a planar view. In FIG. 4, the view illustrated is that of the surface of the stabilizing strap 25 facing away from the surface of the shoe 28. A layer 46 of hook-like material is disposed proximate the end of the dorsal strap 26. A layer 48 of fibrous material is disposed on the surface of the dorsal strap 26 adjacent the layer 46. The hook-like material in the layer 46 is operable to mesh with the fibrous material in the layer 48 to form an attachment therefor. This type of material is commonly referred to under the trade name &#34;Velcro&#34;. A layer of hook-like material 50 is disposed proximate the end of the strap 30 and a layer of fibrous material 52 is disposed adjacent the layer of hook-like material 50. The layers 50 and 52 are similar to the layers 46 and 48, respectively. 
     The free end of the dorsal strap 26 having the layer 46 disposed thereon is inserted through the ring clasp 42 on the connecting strap 36 and folded back over itself such that the layer 46 contacts the layer 48 on the surface thereof. The two layers 46 and 48 are designed to provide a resistance to shear forces therebetween but the application of forces perpendicular to the surface of the dorsal layer 26 at the connection between the layers 46 and 48 results in separation thereof. Therefore, the dorsal strap 26 can be tightened through the ring clasp 42 and the two layers 46 and 48 attached together to provide sufficient shear force to retain the tension therein. The free end of the strap 30 is inserted through the ring clasp 44 in a similar manner with the layers 50 and 52 providing the attachment therefor. 
     Referring now to FIG. 6, a force relief pad 54 is attached to the surface of the Achilles strap 30 such that the pad 54 is adjacent the surface of the shoe 28. The pad 54 is oriented on the surface of the strap 30 such that the pad will cover the tendo-calcaneus and evenly disperse the force across the surface and the sides thereof. A force relief pad 56 is disposed on the opposite side of the connection point 34 for contacting the medial side of the shoe 28. The pads 54 and 56 are fabricated of neoprene rubber in the preferred embodiment. 
     As described above, the connection point 34 is disposed adjacent and slightly below the navicular bone. This portion of the foot anatomy is very sensitive in that both the anterior tibial tendon and posterior tibial tendons attach in this region. Referring back to FIG. 1, the anterior tibial tendon attaches to the points 57 on the cuneiform bone 16 and the base of the first metatarsal bone. The posterior tibial tendon attaches to the points 59 on the undersurface of the navicular bone 14 and. the cuneiform bone 16. The posterior and anterior tibial tendons extend about the navicular tuberosity and can be a point of irritation during exercise. Therefore, the force relief pad 56 provides some conformation to the lateral side of the foot and, in addition, raises the dorsal strap 26 at the connection point 34 slightly above the surface of the shoe 28. In this manner, the pressure applied to the area proximate the navicular tuberosity and the insertion points of the anterior and posterior tibial tendons is minimized. 
     Referring further to FIGS. 5 and 6, the operation of the dorsal, Achilles and plantar straps will be described in more detail. Prior to exercise, the plantar strap 32 is disposed under the sole of the shoe, the Achilles strap 30 placed over the back of the shoe and the dorsal strap 26 placed over the dorsum of the shoe. The free ends of the dorsal strap 26 and the Achilles strap 30 are inserted through the ring clasps 42 and 44, respectively. The individual then tightens the dorsal strap 26 and the Achilles strap 30 to provide a desired level of comfort and support. The plantar strap 32 supplies a force vector that is directed towards the infratalar joints and proximate the attachment point of the planta fascia to the calcaneus bone. The Achilles strap 30 provides a force vector directed external to the shoe 28 and along the line of motion of the infratalar joints external to the tendo-calcaneus and proximate the attachment point thereof to the calcaneus bone. This force vector is transmitted to the infratalar joints by hydraulic action in the foot. 
     The dorsal strap 26 provides a force vector that is directed external to the shoe 28 and on the dorsum of the foot and essentially along the line of motion of the infratalar joints. When a shock is received to the foot during exercise, force applied to one portion of the foot, such as the heel, is dispersed through the foot by hydraulic action. The dorsal strap 26, Achilles strap 30 and plantar strap 32 aid the foot in dispersing this motion without excess movement of the infratalar joints and also improves shoe-foot conformation. 
     The shoe-foot conformation provided by the present invention is important in that the arch of the foot contacts the inner sole of the shoe 28 which is normally formed as an arch support to provide support for the arch of the foot. If the foot is allowed to slip within the shoe 28, support for the arch would be reduced and this would result in excess pronation of the foot since the lateral side of the foot would exhibit a tendency to turn outward during impact of the heel which can result in some pain. Therefore, the increased shoe-foot conformation provided by the stabilizing strap 25 can alleviate some of the pain due to excess pronation of the foot resulting from movement of the infratalar joints. 
     Since the tension of each of the straps 26 and 30 can be adjusted by the individual, the amount of force applied along the line of motion of the infratalar joints can therefore be adjusted. For example, during running, the foot can have a tendency to swell and sweat resulting in a change in the shoe-foot conformation. In order to adjust this, it is only necessary to adjust the tension in each of the straps. Sometimes this may require two or three adjustments during an exercise routine. Without allowing for adjustment of the straps 26 and 30, a great deal of discomfort could result during the exercise routine. 
     In the preferred embodiment, the angle between the center lines of the straps 26 and 30 is approximately 90° and the angle of each of the straps 26 and 30 with respect to the center line of the plantar strap 32 is approximately 45° such that the straps 26, 30 and 32 form a &#34;Y&#34; configuration. In a similar manner, the angle between the connecting straps 36 and 38 is approximately 90° and the angle of each of the straps 36 and 38 with respect to the center line of the plantar strap 32 is approximately 45°. However, it should be understood that the angular relationships of the straps in the preferred embodiment is not a limitation and can be altered to provide a stabilizing strap customized for an individual&#39;s personal foot anatomy. In addition, the attachment points 34 and 40, although shown fixed, can be pivoted such that the dorsal strap 26 and the Achilles strap 30 pivot about the attachment point 34 and the connecting straps 36 and 38 pivot about the connecting point 40. This allows an individual to place the straps 26 and 30 at the position to provide maximum stabilization of the infratalar joints. In addition to providing force relief, the pad 54 also provides friction to keep the strap 30 from moving. Although not shown, an additional pad can be disposed on the undersurface of the dorsal strap 26 to prevent slipping thereof. This maintains the selected position of the straps 26 and 30 with respect to the shoe. 
     Referring now to FIG. 7, there is illustrated an alternate embodiment of the present invention. Points 58 are integrally molded with the sole of a shoe 60. A dorsal strap 62 is disposed over the dorsal of the foot external to the shoe 60 in a similar manner to the dorsal strap 26. However, the dorsal strap 62 is wider than the dorsal strap 26 of FIG. 2 with relation to the respective one of the shoes 28 or 60. An Achilles strap 64 is disposed over the tendo-calcaneus in a similar manner to the positioning of the Achilles strap 30. However, the Achilles strap 64 is permanently rooted through a slip 66 in the heel of the shoe and disposed higher than the dorsal strap 62. A pad 68 is disposed on the undersurface of the Achilles strap 64 and provides relief for the medial portion of the tendo-calcaneus. Although not shown, the Achilles strap 64 and the dorsal strap 62 have a free end which is inserted through associated ring clasps on the medial side of the shoe 60 that are similar to the ring clasps 42 and 44 of the embodiment of FIGS. 2-4. In addition, a relief pad (not shown) is disposed under the connection point for the straps 62 and 64 on the medial side of the plantar strap 32. 
     Referring to FIG. 8, there is illustrated a top view of the shoe 60 of FIG. 7. A pad 70 is provided on the instep under two instep flaps 72 and 74. The dorsal strap 62 is illustrated in phantom lines. The pad 70 is similar in construction to the pads 54 and 56 of FIG. 6 and provides force relief over the dorsum of the foot and proximate to the sensitive tendon insertion points thereon. When the dorsal strap 62 is tightened, the flaps 72 and 74 move together to tighten the shoe 60 about the instep of the foot. Therefore, the Achilles strap 64 and the dorsal strap 62 provide the primary securing function of the shoe about the foot while also stabilizing the infratalar joints. 
     Referring to FIG. 9, there is illustrated a planar view of another alternative embodiment of the present invention. The stabilizing strap 80 is of a y-shaped one-piece construction for being disposed external to a shoe. Stabilizing device 80 comprises a plantar strap 82 for disposal beneath the inner sole of a shoe. A first dorsal strap 84 is attached at one end thereof to the medial end of plantar strap 82 and a second dorsal strap 86 is attached at one end thereof to the lateral end of plantar strap 82. Dorsal straps 84, 86 are adapted to overlay the exterior surface of the shoe adjacent the dorsum of the foot on the medial and lateral sides thereof, respectively. Eyelets 88 are provided along the edges 90, 92 of dorsal straps 84, 86. 
     Stabilizing strap 80 also comprises an Achilles strap 94 for being disposed on the shoe adjacent the tendo-calcaneus proximate the attachment point thereof to the calcaneus bone. Achilles strap 94 is attached at one end thereof to the medial end of plantar strap 82. A ring clasp 96 is attached to the lateral end of plantar strap 82 for receiving the free end of Achilles strap 94. A layer of hook-like material (not shown) is disposed on the exterior surface of strap 94 proximate the free end and a layer of fibrous material (not shown) is disposed on the ventral surface. The layers are similar to the layers 50, 52 described above. Achilles strap 94 thus cooperates with ring clasp 96 to enable adjustable tensioning of Achilles strap 94 about the shoe in the manner described above with respect to ring clasp 44 and Achilles strap 30. 
     FIGS. 10 and 11 illustrate lateral and medial views of the stabilizing strap 80 as an integral part of a shoe 98. As shown in the Figures, plantar strap 82 is fixedly secured to the sole of the shoe and extends beneath the inner sole of shoe 98 between the mid sole 100 and the outer sole 102 proximate the attachment point of the plantar fascia to the calcaneus bone. An orienting loop 104 is disposed proximate the heel 106 of shoe 98 which receives the free end of Achilles strap 94 for proper disposal of the strap over the tendo-calcaneus proximate the attachment point to the calcaneus bone. Achilles strap 94 is thus extended from the medial side of shoe 98 through loop 104 and is then inserted through ring clasp 96 on the lateral side of the shoe and adjusted therethrough to tension Achilles strap 94 about shoe 98 and thus provide the desired level of comfort and support. As described above with respect to FIG. 9, dorsal straps 84, 86 extend over the dorsum of the foot on the exterior of shoe 98 on the lateral and medial sides thereof respectively. 
     As best seen in FIG. 12, a lace 108 is provided to extend between edges 90, 92 of dorsal straps 84, 86 and to thus adjustably tension the dorsal straps about shoe 98. As shown in FIG. 12, lace 108 is attached to the lowermost opposed pair of eyelets 88 and then criss-crossed into the other eyelets in the conventional manner. Achilles strap 94 and dorsal straps 84, 86 thus secure the shoe about the foot while also stabilizing the infratalar joints. 
     In summary, there has been provided a stabilizing device that stabilizes motion about the infratalar joints. The stabilizing device includes a dorsal strap for disposal about the dorsum of the foot, an Achilles strap for disposal over the tendo-calcaneus adjacent the attachment point thereof to the calcaneus bone and a plantar strap for disposal under the sole of the foot exterior to the shoe and proximate the attachment point of the plantar fascia to the calcaneus bone. The plantar strap, dorsal strap and Achilles strap are of a one-piece y-shaped construction with the dorsal strap consisting of two components overlaying the dorsum of the foot exterior to the shoe on the medial and lateral sides thereof and interconnected through a conventional lacing system. The dorsal straps are adjustably tensioned through the lacing system. A ring clasp is attached to the plantar strap for receiving the Achilles strap and allowing for adjustable tensioning thereof. By tensioning the dorsal and Achilles straps, a stabilizing force can be directed along the line of motion of the infratalar joints of the foot. The stabilizing device therefor stabilizes the infratalar joints and increases shoe-foot conformation during exercise. The adjustablility on the tension on the dorsal and Achilles straps allows for adjustment during an exercise routine such that compensation is made for swelling of the foot. 
     Although the preferred embodiment has been described in detail, it should be understood that various changes, substitutions and alterations can be made therein, without departing from the spirit and scope of the invention as defined by the appended claims.