Abstract:
A knee brace assembly for various uses, e.g., restricting anterior tibial movement. The knee brace assembly includes a proximal cuff for engaging the wearer&#39;s leg above the knee and a distal cuff for engaging the wearer&#39;s leg below the knee. The proximal and distal cuffs are linked together by a hinge that permits pivotal movement of the proximal cuff relative to the distal cuff. The proximal cuff has lateral and medial portions each having a slot extending there along. A strap guiding assembly is slidably mounted within each of the slots. Each strap guiding assembly is arranged to slide between a proximal extreme when the wearer&#39;s leg is in flexion and a distal extreme as the wearer extends his or her leg. A biasing device biases each strap guiding assembly towards its proximal extreme. A cross-strap, having free ends and a length, is provided for engagement with the wearer&#39;s leg. The cross-strap attaches to the wearer&#39;s leg below the knee and wraps behind the knee in crisscross fashion. The free ends of the strap attach to the strap guiding assembly. The cross-strap is operative in response to extension of the wearer&#39;s leg to pull the strap guiding assembly from the proximal extreme towards the distal extreme thus creating a force counteractive to abnormal anterior movement of the tibia.

Description:
This invention relates generally to orthopedic knee braces, and more particularly to knee braces for use by persons having anterior cruciate ligament laxity or insufficiency to protect them from injury due to abnormal anterior tibial movement. 
     BACKGROUND OF THE INVENTION 
     Various types of knee braces are shown in the patent literature and are commercially available. The following constitute examples of prior art braces that deal with restricting anterior movement of the tibia: U.S. Pat. Nos. 4,9055,369 (Bledsoe et al.); 5,433,699 (Smith, III); 4,751,920 (Mauldin et al.) and 4,781,180 (Solomonow). The apparatus shown by Mauldin is a knee brace that has a first attachment portion to attach the brace to the wearer&#39;s thigh and a second attachment portion to attach the brace to the wearer&#39;s tibia and a hinge connected to the medial side of the first and second attachment portions by way of a thigh bar and tibia bar, respectively. An adjustable gearing mechanism located at the hinge permits the wearer to limit the amount of rotation of the tibia bar with respect to the thigh bar. However, this brace suffers from failing to be able to prevent anterior translation of the tibia by the application of posterior pressure directed at the tibia tubercle location. Instead, like its predecessors, the Mauldin apparatus attempts to limit tibial rotation by limiting medial hinge motion. 
     The apparatus shown by Solomonow is a knee brace having an upper framework attached to the thigh and a lower framework attached to the lower leg just below the knee. These two frameworks are hinged on the medial and lateral sides of the leg (bilateral hinge). A bell crank is pivotally connected to the lower framework. An adjustable screw coupled to one side of the bell crank engages an offset portion of the upper framework whenever the leg is extended. The other side of the bell crank is coupled to a tibial restraining strap. As the leg is extended, the lower framework and bell crank are rotated counterclockwise until the offset of the upper framework contacts the screw, rotating the bell crank in a clockwise direction and thereby tightening the tibial restraining strap against anterior movement of the tibia. 
     The apparatus as shown by Bledsoe et al. is a knee brace which also utilizes bilateral hinges to connect the thigh support and calf support sections. The bilateral hinges basically comprise adjustable drive plates that alternate the pivoting point of the thigh support and calf support throughout leg flexion and extension. By varying the pivot point at different points throughout leg extension, a counter shearing force is generated to reduce the shearing force created by the quadriceps muscle which cause the undesirable anterior shift of the tibia of the leg. 
     Other prior art knee braces are disclosed in U.S. Pat. Nos. 3,581,741 (Rosman); 5,277,698 (Taylor); 5,512,039 (White); 3,387,305 (Shafer); 4,240,414 (Theisler); 4,805,606 (McDavid, III); 4,961,416 (Moore et al.); and U.S. Pat. No. 4,854,308 (Drillio). 
     Examples of prior art knee braces which are commercially available are: Innovative Sports C.Ti., C.Ti. 2 , C.Ti. 2  Lite, Edge, Edge Lite, Sentry, C180 and MVP all of which are sold by Innovation Sports, Inc. Of Irvine, Calif.; Cincinnati ACL which is sold by Brace Technologies, Inc. Of Cincinnati, Ohio, the OS-5 (TM) non-custom functional knee support which is sold by Omni Scientific, Inc. Of Martinez, Calif.; the Lennox Hill (TM) OTS Brace and Spectralite Brace which are sold by 3M Health Care of Long Island City, N.Y.; the SKO (TM) and TKO (TM) knee orthoses which are manufactured by Orthotic Consultants of Southern California; the ACL model knee brace which is sold by Townsend Design of Bakersfield, Calif.; the DONJOY 4-Point (TM), Gold-Point (TM), Playmaker (TM), and Defiance (TM) all of which are sold by Smith &amp; Nephew Donjoy, Inc. of Carlsbad, Calif.; the Poli-Axial Osteoarthritis Brace which is sold by Generation Orthotics, Inc.; and, the ECKO (TM) II Extension Control Knee Orthosis which is sold by Orthomedics of Brea, Calif. 
     While the aforementioned patents seem suitable for their intended purposes, it would be a significant advance in the art to provide a knee brace assembly that applies posterior pressure on the wearer&#39;s tibia in response to extension of the wearer&#39;s leg through the use of a cross-strap that is positioned over the wearer&#39;s tibia, wrapped in crisscross manner behind the wearer&#39;s knee and attached to biased strap guides slidably mounted to the brace assembly. 
     OBJECTS OF THE INVENTION 
     Accordingly, it is a general object of this invention to provide a knee brace assembly which overcomes the disadvantages of the prior art. 
     It is a further object of this invention to provide a knee brace assembly for restricting anterior movement of the wearer&#39;s tibia. 
     It is a further object of this invention to provide a knee brace assembly for restricting abnormal anterior tibial movement without preventing the wearer from being able to fully extend his/her leg. 
     It is a further object of this invention to provide a knee brace assembly that is inexpensive to manufacture. 
     It is a further object of this invention to provide a knee brace assembly that is reliable in operation. 
     It is a further object of this invention to provide a knee brace assembly that is simple in construction. 
     It is a further object of this invention to provide a knee brace assembly that is lightweight. 
     It is a further object of this invention to provide a knee brace assembly that is comfortable when worn. 
     SUMMARY OF THE INVENTION 
     These and other objects of this invention are achieved by providing a knee brace assembly for restricting anterior tibial movement. The knee brace assembly includes a proximal cuff for engaging the wearer&#39;s leg above the knee and a distal cuff for engaging the wearer&#39;s leg below the knee. The proximal and distal cuffs are linked together by a hinge means that permits pivotal rotation of the proximal cuff relative to the distal cuff. The proximal cuff has lateral and medial portions each having a slot extending there along. A strap guiding means is slidably mounted within each of the slots. Each strap guiding means is arranged to slide between a proximal extreme when the wearer&#39;s leg is in flexion and a distal extreme as the wearer extends his or her leg. A biasing means biases each strap guiding means towards its proximal extreme. A cross-strap, having free ends and a length, is provided for engagement with the wearer&#39;s leg. The cross-strap attaches to the wearer&#39;s leg below the knee and wraps behind the knee in crisscross fashion. The free ends of the strap attach to the strap guiding means. The cross-strap is operative in response to extension of the wearer&#39;s leg to pull the strap guiding means from the proximal extreme towards the distal extreme thus creating a force counteractive to abnormal anterior movement of the tibia. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     Other objects and many attendant features of this invention will become readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
     FIG. 1 is an isometric view of a first embodiment of the present invention; 
     FIG. 2 is an enlarged sectional view taken along line  2 — 2  of FIG. 1; 
     FIG. 3 is an enlarged sectional view taken along line  3 — 3  of FIG. 1; 
     FIG. 4 is an enlarged sectional view taken along line  4 — 4  of FIG. 3; 
     FIG. 5 is a sectional view taken along line  5 — 5  of FIG. 1; 
     FIG. 6 is a sectional view taken along line  6 — 6  of FIG. 1; 
     FIG. 7 is an exploded isometric view of a first embodiment of the present invention; 
     FIG. 8 is an isometric view of a second embodiment of the present invention; 
     FIG. 9 is an enlarged sectional view taken along line  9 — 9  of FIG. 8; 
     FIG. 10 is an enlarged sectional view taken along line  10 — 10  of FIG. 8; 
     FIG. 11 is an enlarged view of an area shown in FIG. 10 encircled by a line labeled FIG. 11; 
     FIG. 12 is an enlarged sectional view taken along line  12 — 12  of FIG. 10; 
     FIG. 13 is a sectional view taken along line  13 — 13  of FIG. 8; and, FIG. 14 is an exploded isometric view of a second embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now in greater detail to the various figures of the drawings wherein like reference numerals refer to like parts there is shown at  20  in FIGS. 1,  5  and  7  a first embodiment of the dynamic orthopedic knee brace assembly of the present invention. As shown in FIGS. 1 and 5, the knee brace assembly  20  is shown attached to a human left leg  25  (shown in phantom) having a thigh portion  30 , a knee  35  and leg portion below the knee  40 . The left leg  25  is chosen for convenience only and the brace assembly  20  can be affixed to either the right or left leg. Generally speaking, the knee brace assembly  20  functions to counteract anterior shifting of the tibia when the anterior cruciate ligament in the illustrated leg is missing or damaged. Such anterior shifting of the tibia occurs for a variety of reasons and often occurs when a person is engaging in physical activities that involve sudden turning to the right or to the left, sudden stopping, jumping, running backwards or other types of movement. Where the anterior cruciate ligament is missing or damaged, such anterior shifting of the tibia can also occur when a person simply extends his or her leg from a flexed position towards its fully straightened position (FIGS.  1  and  3 ). Referring now to FIG. 7, the knee brace assembly  20  of the present invention comprises three basic parts: a bracing component  45 , a cross-strap  50  and a sleeve  55 . The bracing component  45  comprises an upper or proximal cuff  60 , which is engageable with a wearer&#39;s thigh, a distal cuff  65 , which is engageable with the wearer&#39;s leg portion below the knee  40 , and a pair of polycentric hinges  70  which pivotally join the cuffs  60  and  65  together. Straps, used for securing the cuffs to the wearer&#39;s leg, are shown generally at  75  and  80 . 
     Referring now to FIGS. 1 and 7, the bracing component  45  is constructed to fit a wearer&#39;s leg as will become apparent hereinafter. The upper or proximal cuff  60 , is formed to fit the anterior portion of the wearer&#39;s leg above the knee, and is essentially curvilinear in configuration and shaped to fit over the wearer&#39;s thigh  30 . The proximal cuff  60  has medial and lateral depending portions  90  and  95 , respectively, and a front arcuate portion  85  (FIG.  1 ). The proximal cuff  60  is open at the posterior portion so that it may be placed over the thigh  30  from the anterior or front. The distal cuff  65  is similar in construction to the proximal cuff in that it is curvilinearly shaped and formed to fit the anterior portion of the wearer&#39;s leg portion below the knee  40 . It also includes a front arcuate portion  100 , a medial depending portion  110  and a lateral depending portion  105 . 
     The proximal and distal cuffs  60  and  65  and the polycentric hinges  70  are made of lightweight, high impact thermoplastic material which can be formed to fit the contours of the individual wearer&#39;s leg. The cuffs  60  and  65  may be fabricated from any suitable material, e.g., carbon fiber filament, carbon fiber filament and polymer composite, carbon/titanium composite, woven carbon fiber infused with acrylic resin. Preferably, the cuffs  60  and  65  are fabricated from a material that is water resistant and non-corrosive to enable the wearer to use the knee brace assembly in a full range of activities including working, walking, running, vigorous athletics and high-impact sports including freshwater and salt water sports. 
     Referring now to FIGS. 6 and 7, the proximal cuff  60  is padded on the inside surface by a durable non-allergenic foam pad  115 . In FIG. 6, a top view of the knee brace assembly  20  is shown wherein the inside surface of the proximal cuff is provided with a VELCRO® hook patch  135  secured, e.g., glued, thereon that is arranged to be brought into engagement the plush exterior surface of the foam pad  115 . 
     As shown in FIG. 7, the polycentric hinges  70  are also padded on the inside surface by a durable non-allergenic foam pad  120 . The padded cuff and hinges are positioned to absorb anterior or frontal impacts, as well as lateral impacts to the outside of the leg and medial impacts to the inside of the leg. 
     Referring now to FIGS. 1,  6  and  7 , the cuff strap  75  provides releasable securement of the proximal cuff  60  to the wearer&#39;s thigh  30 . The cuff strap  75  may be formed of any suitable flexible material, e.g., nylon, and includes an elastic segment  77 , VELCRO® loop segments  76  secured to the inner and outer surfaces thereof by any suitable means, e.g., sewing. The cuff strap  75  also includes VELCRO® hook segment  125  disposed at the free ends thereof. The free ends of the cuff strap  75  are slipped through and looped around elongated slots  130  located on opposite sides of the proximal cuff  60 . Each free end of the cuff strap  75  is then folded back onto itself so that the hook segment  125  releasably engages the loop segment  76  thereby permitting the strap  75  to be tightened or loosened for comfort. The cuff strap  80  provides releasable securement of the distal cuff  65  to the wearer&#39;s leg below the knee  40  in a similar manner. 
     Referring now to FIGS. 1,  5  and  7 , the medial and lateral depending portions  90  and  95  of the proximal cuff  60  each include a vertically oriented elongated slot  140 . As best shown in FIG. 7, a strap guide assembly  145   a  is slidably mounted within the elongated slot  140  located on the lateral depending portion  95 . Likewise, as best shown in FIG. 5, a strap guide assembly  145   b  is slidably mounted within the elongated slot  140  located on the medial depending portion  90  of the proximal cuff  60 . 
     Referring now to FIGS. 3 and 4, the strap guide assembly  145   a  shown therein includes a ring portion  146  trapped within a bracket portion  148 . The bracket portion  148  is disposed over the outside surface of the lateral depending portion  95  of the proximal cuff  60 . The strap guide assembly  145   a  also includes a flange portion  149  disposed on the inside surface of the lateral depending portion  95  of the cuff. The bracket  148  and flange  149  portions of the strap guide assembly  145   a  are held together and slidably mounted to the slot  140  by means of a rivet assembly  147  that enables the strap guide assembly  145   a  to slidably move within the slot  140  between two extremes: a distal extreme, as shown in FIG. 1 and a proximal extreme, as shown in FIG.  7 . 
     Referring again to FIG. 3, an elastic band  160 , e.g., a rubber band, is anchored at one of its ends to the flange  149  by any suitable means, e.g., tying. At its opposite end, the elastic band  160  is anchored to the inside surface of the lateral depending portion  95  of the proximal cuff  60  by any suitable means, e.g., rivet  166 . In this manner, the elastic band  160  serves as a means for normally biasing the strap guide assembly  145   a  to the proximal extreme within the vertically oriented slot  140  as shown in FIG.  7 . 
     As best shown in FIG. 5, the strap guide assembly  145   b  is slidably mounted within the elongated slot  140  located on the medial depending portion  90  of the proximal cuff  60 . The strap guide assembly  145   b  is similar in construction to the strap guide assembly  145   a  and includes a ring portion  165  trapped within a bracket portion  170  disposed over the outside surface of the medial depending portion  90  of the proximal cuff  60 . The strap guide assembly  145   b  also includes a flange portion  175 , the bracket and flange portions,  170  and  175 , respectively, being held together and slidably mounted to the slot  140  by means of a rivet assembly  180  to enable the strap guide assembly  145   b  to slidably move between distal and proximal extremes. An elastic band  185 , e.g., a rubber band, is anchored at one of its ends to the flange  175  by any suitable means, e.g., tying. At its opposite end, the elastic band  185  is anchored to the inside surface of the medial depending portion  90  of the proximal cuff  60  by any suitable means, e.g., rivet  190 . In this manner, the elastic band  185  serves as a means to normally bias the strap guide assembly  145   b  to the proximal extreme within the vertically oriented slot  140  as shown in FIG.  5 . 
     Referring now to FIGS. 1,  5  and  7 , the prosthetic sleeve  55  is provided to assist in the attachment of the cross strap  50  and may be constructed of any suitable material, e.g., one-eighth inch thick neoprene having a brushed nylon outer surface and a smooth neoprene inner surface. The sleeve  55  is shown as being arranged to be wrapped around and secure to the wearer&#39;s leg portion just below the knee  40 . An alternative sleeve, such as a full patella support sleeve which wraps around and secures to the wearer&#39;s thigh and calf, both above and below the wearer&#39;s knee could be utilized in substitution for the sleeve  55  in accordance with this invention. As best shown in FIG. 7, the sleeve  55  is provided with a laterally extending attachment strap  191  on which a VELCRO® hook segment is disposed. As best shown in FIG. 5, once the sleeve  55  is wrapped around the wearer&#39;s calf just below the knee  35 , the hook segment on the attachment strap  191  releasably engages the plush outer surface of the sleeve  55  thereby permitting the sleeve  55  to be tightened or loosened for comfort. 
     Referring now to FIG. 7, the cross-strap  50  is formed of a non-elastic flexible web using any suitable material, e.g., nylon, and comprises an interior surface (best shown in FIGS.  2  and  7 ), an exterior surface (best shown in FIG. 2) and free ends to which VELCRO® hook patches  200  and  205  are secured. As best shown in FIGS. 2 and 7, VELCRO® loop segments  206  are secured to both the interior and exterior surfaces of the cross-strap  50  by any suitable means, e.g., sewing. Positioned on the interior surface of the cross-strap  50  approximately midway along the length thereof is a VELCRO® hook patch  195  arranged for releasable securement with the plush exterior surface of the sleeve  55  at a position on the sleeve  55  that lies over the wearer&#39;s tibia just below the wearer&#39;s knee  35 . The positioning of the hook patch  195  on the outer surface of the sleeve  55  is best illustrated in FIG.  1  and by the dotted line  199  in FIG.  7 . The cross-strap  50  is also provided with a pad  59  slidably mounted thereon to be positioned behind the wearer&#39;s knee when the cross-strap is secured to the wearer&#39;s leg in the manner described below. 
     Referring now to FIGS. 1 and 5, once the hook patch  195  cross strap  50  is releasably secured to the sleeve  55  in the manner described above, the proximal and distal cuffs  60  and  65  of the bracing component  45  are releasably secured to the wearer&#39;s thigh  30  and leg portion below the knee  40  by attachment with straps  75  and  80 . As best shown in FIG. 2, a VELCRO® hook patch  209  is secured, e.g., glued, to the inside surface of the distal cuff  65  and is provided to engage with the plush exterior surface of the sleeve  55  thus providing an added means for securing the distal cuff  65  to the wearer&#39;s leg portion below the knee  40 . 
     Thereafter, the free ends of the cross-strap  50  are crossed behind the wearer&#39;s knee  35  and slipped through and looped around the ring portions  146  and  165  of the pivotally mounted strap guide assemblies  145   a  and  145   b.  Each free end of the cross-strap  50  is then folded back onto itself so that the hook patches  200  and  205  releasably engage the loop segments  206  of the cross-strap  50  thereby permitting the cross-strap  50  to be tightened or loosened for comfort. The slidable pad  59  may be positioned behind the wearer&#39;s knee to suit the user&#39;s comfort. In accordance with this invention, when releasably securing the free ends of the cross-strap to the strap guide assemblies  145   a  and  145   b,  the wearer must maintain his or her knee in approximately thirty degrees of flexion. Moreover, the cross-strap must be applied to fit snugly around the wearer&#39;s knee but not so tightly as to be uncomfortable. 
     During use of the knee brace assembly  20 , when the wearer&#39;s leg is fully flexed, the quadriceps muscle exerts only a relatively slight anterior displacement force on the tibia. This displacement force increases significantly as the wearer extends his or her leg closer and closer toward the fully extended position. It can be readily seen that when wearing the brace  20 , as the wearer begins to extend his or her leg  25  towards full extension, the cross-strap  50  tightens geometrically around the wearer&#39;s knee  35  above and below the joint line and also applies posteriorly directed pressure to the anterior portion of the wearer&#39;s tibia just below the knee. The posteriorly directed pressure exerted against the tibia by the cross-strap  50  restrains anterior translation of the tibia. 
     At this juncture, it is important to point out that anterior tibial translation can result from a number of causes other than displacement forces created by the quadriceps muscle. For example, anterior tibial translation can result from force exerted against the tibia when the wearer is engaged in physical activity that involves sudden turning to the left or right, sudden stopping, jumping and running backwards. The posteriorly directed pressure exerted against the tibia by the cross-strap  50  will restrain anterior translation of the tibia during such physical activity. 
     At the same time, the cross-strap  50  applies a tensile force upon the strap guide assemblies  145   a  and  145   b  urging them to move from their normally biased proximal extreme to their distal extreme. As the strap guide assemblies move towards the distal extreme, the elastic bands  160 ,  185  will stretch and exert a counteractive tensile force upon the strap guide assemblies resistive to their distal movement. The movement of the strap guide assemblies enables the wearer to straighten his or her leg into full extension while applying increasing amounts of pressure to the wearer&#39;s tibia just below the knee. 
     Referring now to FIGS. 8 and 14, there is shown at  300  a second embodiment of the dynamic orthopedic knee brace assembly of the present invention. As best shown in FIG. 14, the knee brace assembly  300  shown therein comprises three basic parts: a bracing component  305 , a cross-strap  310  and a sleeve  315 . The knee brace assembly  300  functions to counteract anterior shifting of the tibia that can occur during physical activities that involve sudden turning to the right or left, sudden stopping, jumping or running backwards when the anterior cruciate ligament in the illustrated leg is missing or damaged. 
     As best shown in FIGS. 8 and 14, the bracing component  305  comprises a pair of elongated rigid thigh support members  320  and  325  extending along medial and lateral sides of the thigh, respectively, and a pair of elongated rigid lower leg support members  330  and  335  extending along the medial and lateral sides of the wearer&#39;s leg portion below the knee, respectively. The inner ends of the thigh and lower leg support pairs are pivotally interconnected by means of a pair of polycentric hinges  340 . The thigh support members  320 ,  325 , lower leg support members  330 ,  335  and polycentric hinges  340  are made of any suitable lightweight material, e.g., carbon fiber filament, thermosensitive carbon composite materials. Preferably, these components are fabricated from a material that is water resistant and non-corrosive to enable the wearer to use the knee brace assembly in a full range of activities including working, walking, and vigorous athletics. The polycentric hinges  340  are padded on the inside surface by a durable non-allergenic foam pad  345 . 
     As best shown in FIGS. 8 and 14, the support members are releasably secured to the wearer&#39;s leg (not shown) above and below the knee by means of straps shown generally at  350 ,  352 ,  355 ,  360 ,  362 ,  365  and  367 . Referring now to FIG. 9, a top view of the knee brace assembly  300  is shown therein illustrating the manner in which the straps  350  and  352  releasably secure the rigid thigh support members  320  and  325  to the wearer&#39;s thigh. The straps  350  and  352 , shown therein, each include a VELCRO® hook segment  351  disposed at each end thereof. One end of the strap  350  is slipped through and looped around an elongated slot  375  located in the thigh support member  320  while the other end of the strap  350  is slipped through and looped around an elongated slot  380  located in the thigh support member  325 . One end of the strap  352  is slipped through and looped around an elongated slot  385  located in the lateral thigh support member  320  while the other end of the strap  352  is slipped through and looped around an elongated slot  390  located in the medial thigh support member  325 . Each end of the straps  350  and  352  is then folded back onto itself so that the hook segments  351  releasably engage VELCRO® loop segments secured, e.g., sewn, to the outer surface of the straps  350  and  352  thereby permitting the straps  350  and  352  to be tightened or loosened for comfort. Referring now to FIGS. 8 and 14, the strap  355  slips through and loops around elongated slots  381  and  386  and releasably engages to itself in the manner in which strap  350  and  352  releasably engage. 
     Referring now to FIG. 8, straps  355 ,  360 ,  362 ,  365  and  367  releasably secure the rigid lower leg support members  330  and  335  to the wearer&#39;s leg portion below the knee in a manner similar to that described above in connection with releasable attachment of the rigid thigh support members to the wearer&#39;s thigh using straps  350 ,  352  and  355 . 
     Referring now to FIGS. 8 and 14, the rigid thigh support member  320  includes a vertically oriented elongated slot  395  in which a strap guide assembly  400  is slidably mounted. Similarly, the rigid thigh support member  325  includes a vertically oriented elongated slot  396  in which a strap guide assembly  405  is slidably mounted. The strap guide assemblies  400  and  405  each include a ring portion  410  trapped within a bracket portion  415 . As best shown in FIGS. 10 and 11, the bracket portion  415  of each strap guide assembly  400  and  405  is disposed over the outside surface of the thigh support members  320  and  325 . As best shown in FIGS. 8 and 13, each strap guide assembly  400  and  405  also includes a leaf spring  420  disposed on the inside surface of the thigh support members  320  and  325 . As best shown in FIGS. 11 and 14, the bracket portion  415  and one end of the leaf spring portion  420  of the strap guide assemblies  400  and  405  are secured together and mounted on opposite sides of the elongated slots  395  and  396  by means of a rivet assembly  425  that enables the strap guide assemblies  400  and  405  to slidably move within the slots  395  and  396  between two extremes: a distal extreme, as shown in FIGS. 8 and 13, and a proximal extreme (not shown). 
     Referring now to FIGS. 13 and 14, as previously mentioned, one end of the leaf spring  420  is secured to the strap guide assemblies  400  and  405  by means of a rivet  425 . At its other end, the leaf springs  420  is anchored to the inside surface of the rigid thigh support members  320  and  325  by means of a rivet assembly  430 . In this manner, the leaf spring  420  serves as a means for normally biasing the strap guide assemblies  400  and  405  to the proximal extreme within the vertically oriented slots  395  and  396 , respectively. At this juncture it is important to point out that rather than a leaf spring, alternative means could be employed for biasing the strap guide assemblies towards the proximal extreme, e.g., a coiled spring, an elastic band, a rubber band, etc. 
     Referring now to FIGS. 8 and 14, the prosthetic sleeve  315  is provided to assist in the attachment of the cross-strap  310  and may be constructed of any suitable material, e.g., one-eighth inch thick neoprene having a plush outer surface and a smooth neoprene inner surface. The sleeve  315  shown is a full patella support sleeve which wraps around and secures to the wearer&#39;s thigh and calf above and below the wearer&#39;s knee. As best shown in FIG. 14, the sleeve  315  is provided with a laterally extending attachment strap  316  on which a VELCRO® hook segment is disposed. The sleeve  315  also provides a patella opening  317  through which the knee can protrude when the sleeve  315  is worn. Once the sleeve  315  is wrapped around the wearer&#39;s leg, the attachment strap  316  releasably engages the plush outer surface of the sleeve  315  to be tightened or loosened for comfort. 
     The cross-strap  310  is formed of a non-elastic flexible web using any suitable material, e.g., nylon, and comprises free ends, an interior surface, shown in FIG.  14  and an exterior surface, hidden from view in FIG.  14 . The interior surface comprises VELCRO® loop segments  440  secured thereto by any suitable means, e.g., sewing, and a centrally located VELCRO® hook patch  435  also secured thereto by any suitable means, e.g., sewing. The hook patch  435  is arranged for releasable securement with the plush exterior surface of the sleeve  315  just below the patella opening  317  of the sleeve  315 . This position, as best illustrated by the dotted line  399  in FIG. 14, corresponds with the wearer&#39;s tibia. The exterior surface of the cross-strap  310  comprises VELCRO® hook patches  445  at the free ends thereof and a VELCRO® loop segment (not shown) extending therebetween. The cross-strap  310  is also provided with a pad  359  slidably mounted thereon to be positioned behind the wearer&#39;s knee when the cross-strap  310  is releasably secured to the wearer&#39;s leg. 
     Once the cross-strap  310  is releasably secured to the sleeve  315  at the location described above and illustrated in FIG. 14, i.e., just below the patella opening  317 , the bracing component  305  is releasably secured to the wearer&#39;s thigh and leg portion below the knee using straps  350 ,  352 ,  355 ,  360 ,  362 ,  365  and  367 . Thereafter, the free ends of the cross-strap  310  are crossed behind the wearer&#39;s knee and slipped through and looped around the ring portions  410  of the pivotally mounted strap guide assemblies  400  and  405 . Each free end of the cross-strap  310  is then folded back onto itself so that the hook patches  445  releasably engage the loop segment secured thereby permitting the cross-strap  310  to be tightened or loosened for comfort. 
     During use of the knee brace assembly  300 , when the wearer&#39;s leg is fully flexed, the quadriceps muscle exerts only a relatively slight anterior displacement force on the tibia. This displacement force increases significantly as the wearer extends his or her leg closer an closer toward the fully extended position. It can be readily seen that when wearing the brace  300 , as the wearer begins to extend his or her leg towards full extension, the cross-strap  310  tightens geometrically around the wearer&#39;s knee above and below the joint line and also applies posteriorly directed pressure to the anterior portion of the wearer&#39;s tibia just below the knee. This posteriorly directed pressure exerted against the tibia by the cross-strap  310  restrains anterior translation of the tibia. 
     At this juncture, it is important to point out that anterior tibial translation can result from a number of causes other than displacement forces created by the quadriceps muscle. For example, anterior tibial translation can result from force exerted against the tibia when the wearer is engaged in physical activity that involves sudden turning to the left or right, sudden stopping, jumping and running backwards. The posteriorly directed pressure exerted against the tibia by the cross-strap  310  will restrain anterior translation of the tibia during such physical activity. 
     At the same time, the cross-strap  310  applies a tensile force upon the strap guide assemblies  400  and  405  urging them to move from their normally biased proximal extreme to their distal extreme. As best shown in FIG. 13, as the strap guide assemblies move towards the distal extreme, the leaf springs  420  will compress and exert a counteractive tensile force upon the strap guide assemblies resistive to their distal movement. The movement of the strap guide assemblies enables the wearer to straighten his or her leg into full extension while exerting additional counteractive force to prevent anterior translation of the tibia.