Abstract:
A hinge for orthopedic braces includes a pair of support arms, a pair of pivot pins and a hinge plate. The arms are coupled to the hinge plate through the pivot pins and are rotateable between an extension position and a flexion position. The hinge plate has a plurality of adjustment apertures for selective reception of an extension limit pin and a flexion limit pin to selectively restrain rotation of the arms beyond an extension limit and a flexion limit. The pins are retained on the hinge by flexible retainers and are individually positionable among the apertures to adjust the range of motion of the arms. A pair of cover elements pivotally moveable in a plane parallel to the hinge plate provide an open position accommodating access to the pins and a closed position preventing inadvertent displacement of the pins from the apertures.

Description:
FIELD OF THE INVENTION 
   The present invention relates to an orthopedic articulating brace, and more particularly, to an orthopedic polycentric hinge for knee braces having rigid relatively moveable support arms and means for conveniently adjusting the range of motion permitted between the arms. 
   BACKGROUND 
   The present invention constitutes an improvement on the polycentric hinge disclosed in U.S. Pat. No. 5,443,444, issued Aug. 22, 1995. 
   As described in said patent, the human knee joint provides for relative articulation of the upper and lower legs, between the femur and tibia, through a plurality of centers or axes over an arc of about 180°. To effectively duplicate the movement of the human knee joint when necessary to mechanically assist the knee, for example, following injury or a surgical procedure, the art has developed articulated knee supporting braces embodying plural axis or polycentric hinges worn about the knee of the patient. These hinges may be used to support the knee joint throughout its full range of motion, or to lock the knee joint in a selected position, or to limit the allowed range of motion of the joint to less than complete extension (straightening) and/or to less than complete flexion (bending) of the knee. During rehabilitation, it is common to initially limit articulation of the knee and to progressively increase the permitted range of motion in gradual increments as healing progresses. 
   Examples of prior art developments in knee braces may be found in U.S. Pat. Nos. 5,292,303 to Bastyr, et al., U.S. Pat. No. 401,933 to DeCamp, U.S. Pat. No. 5,062,858 to Broeck et al., U.S. Pat. No. 4,732,143 to Kausek et al., U.S. Pat. No. 5,038,763 to Wiggins, U.S. Pat. No. 4,726,361 to Farley, U.S. Pat. No. 4,628,916 to Lerman et al., U.S. Pat. No. 3,817,244 to Taylor, U.S. Pat. No. 3,901,223 to May, U.S. Pat. No. 4,372,298 to Lerman, U.S. Pat. No. 4,493,316 to Reed et al., and British Patent No. 1,316,572 and French Patent No. 1,187,444, among others. Some of these patents disclose knee braces with polycentric hinges and others have hinges with a single axis of rotation. 
   U.S. Pat. No. 5,443,444 discloses a polycentric hinge for orthopedic knee braces comprising two rigid support arms having cooperating, interlocking, continuously abutting proximal ends rotateably connected to one another by a polycentric hinge assembly including a pair of pivot pins and a hinge plate. Each rigid support arm is rotatably coupled at its proximal end to the hinge plate by a respective one of the pivot pins. The two arms are pivotable about their respective pivot pins along equal arcs of movement between an adjustable extension position and an adjustable flexion position. The total range of motion of the hinge is from substantially complete extension to substantially complete flexion; the rigid arms being positioned in substantially straight line end-to-end relationship in the complete extension position and being positioned in substantially side-by-side relation in the complete flexion position. The hinge accommodates relative angular movement of the rigid support arms substantially between 0° and 180°. The hinge plate is provided with a plurality of adjustment apertures arranged in an angularly spaced apart pattern for reception of a pair of limit pins to intercept rotation along the arc of rotation of at least one of the arms, thereby to limit rotation of both of the arms. 
   The proximal end portion of the one arm includes an extension facing edge and a flexion facing edge; the extension facing edge being adapted to engage a limit pin in the direction of extension movement and the flexion facing edge being adapted to engage a second limit pin in the direction of flexion movement. The pins, extending through the apertures into which they are inserted, thus restrain movement of the arm beyond the positions defined by the respective limit pins. 
   Adjustment of the permitted range of motion is obtained by repositioning the pins from one aperture to another to adjust the arc of rotation of the pair of arms, preferably in 15° and/or 30° increments, between a final extension position and a final flexion position. Each of the apertures may be labeled according to a specific angular position for extension or flexion, promoting convenient adjustment. 
   An openable cover member, specifically a flip-top cap, is provided to allow selected access to the limit pins for purposes of adjustment and to normally overlie the pins and prevent inadvertent or accidental displacement of the pins from their intended positions of adjustment. Also, each of the limit pins is attached to a respective pivot pin by an individual electrometric tether to retain the limit pins against loss or misplacement, while at the same time allowing the limit pins to be appropriately positioned among the apertures. 
   The flip top cap or cover for the limit pins, unfortunately, is not particularly secure and is prone to popping open, particularly during contact sports, thereby openly exposing the limit pins and permitting the pins to be inadvertently disassociated from their respective apertures, whereupon the hinge is incapable of achieving its intended purpose (unless intended for complete flexion and complete extension). The hinge, until reset, fails its purpose, during which time the knee intended to be protected could suffer further trauma. 
   SUMMARY OF THE INVENTION 
   The primary object of the present invention is to provide an improved and essentially fail proof cover for the limit pins for preventing disassociation of the pins from their respective apertures. 
   A further object of the invention is to provide improved means for retaining the pins in association with the hinge. 
   In accordance with the present invention, a cover for the limit pins is pivotally or swingably mounted on an axis perpendicular to the hinge plate, rather than on an axis parallel to the hinge plate as with the prior flip-top cap, so that the cover is not prone to being dislodged upon impact in a contact sport or otherwise. 
   More particularly, in a preferred embodiment of the invention, the cover is comprised of two cover elements swingably mounted on a pivot axis or pivot axes normal to the plane of the hinge plate and moveable toward and away from one another, somewhat like a clam shell, to selectively cover and uncover the limit pins without being prone to inadvertent or accidental uncovering of the pins. 
   To further secure the cover or cover elements in closed or pin covering position, and to prevent inadvertent or accidental movement of the cover or cover elements to open position, a locking latch is incorporated in the cover assembly. 
   Additionally, the invention provides improved limit pin retaining means comprising a pair of flexible retainers extending slidably around respective ones of the hinge pins and each carrying at their ends a pair of limit pins. 
   The present invention thus provides advantageous improvements on the prior art polycentric hinge. 
   The foregoing and other objects and advantages of the invention will become apparent to those of reasonable skill in the art from the following detailed description, as considered in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view illustrating the components of the hinge of the invention; 
       FIG. 2  is a top plan view of the hinge showing the cover elements in open or pin uncovering positions; 
       FIG. 3  is a top plan view of the hinge showing the cover elements in closed or pin covering position; and 
       FIG. 4  is an enlarged fragmentary cross sectional view taken on line  4 — 4  of  FIG. 3  and illustrating the cover elements in closed and latched position. 
   

   DETAILED DESCRIPTION 
   The following is a detailed description of an embodiment of the invention presently contemplated by the inventors to be the best mode of carrying out their invention. Except for the limit pin cover and retainers, the structure of the hinge is essentially the same as that of U.S. Pat. No. 5,443,444, which is incorporated herein by reference and to which reference is made for a more detailed disclosure of the hinge. 
   Referring to the drawings, an orthopedic polycentric hinge  10  is comprised of a pair of rigid support arms  12 ,  14  juxtaposed to one another at adjacent or proximal ends and which, in relation to the knee of the patient, have forwardly facing edges  12   a ,  14   a  and rearwardly facing edges  12   b ,  14   b . The two support arms  12 ,  14  are pivotally interconnected at their proximal ends by a hinge assembly  16 , comprised preferably of a pair of parallel spaced apart rigid hinge plates  18 ,  20  overlying the opposite sides, i.e., the exterior and interior sides respectively, of the proximal ends of the support arms  12 ,  14  and which are pivotally interconnected to the proximal ends of the arms  12 ,  14 . The hinge plates  18 ,  20  define therebetween a space within which rotation of the arms  12 ,  14  may occur. 
   Preferably, the hinge plates  18  and  20  are each comprised of two elements,  18   a ,  18   b  and  20   a ,  20   b  respectively. The elements  18   a ,  20   a  comprise sturdy metal plates providing structural integrity for the hinge and the elements  18   b ,  20   b  comprise washers, e.g., sheets of low friction material, such as polytetrafluoroethylene, for minimizing friction between relatively moveable parts and facilitating smooth, low friction movement of the arms  12 ,  14 . 
   The hinge plates  18 ,  20  are secured to one another and are pivotally connected to the arms  12 ,  14  by means of a pair of pivot pins or rivets  22  and  24  respectively. The hinge plates  18 ,  20  and pivot pins  22 ,  24  thereby connect the proximal ends of the support arms  12 ,  14  for relative rotation about a pair of spaced parallel axes in a motion that closely approximates the movement accommodated by the human knee joint. 
   As illustrated in the drawings, the hinge will be oriented for attachment to the inner or medial side of the right knee and the outer or lateral side of the left knee when the arm  12  is affixed to the upper leg and the arm  14  is affixed to the lower leg, and will be oriented for attachment to the outer or lateral side of the right knee and the inner or medial side of the left knee when the arm  12  is affixed to the lower leg and the arm  14  is affixed to the upper leg. In either orientation, one of the support arms is secured to the upper leg or thigh of the patient above the injured knee and the other support arm is secured to the lower leg or calf below the knee, with the polycentric hinge properly aligned along side the knee. Depending upon the severity of the injury and the degree of support required, the knee may be supported by a single brace on one side of the knee or by a pair of braces located respectively on opposite sides of the knee. 
   Various means of affixing the support arms to the upper and lower legs of the patient are disclosed in the prior art, for example, U.S. Pat. Nos. 3,786,804, 3,817,244, 4,088,130, 4,361,142, 4,372,298, 4,407,276, 4,493,316 and 4,628,916. To accommodate attachment of the securing means to the brace, a plurality of holes are provided in the arms  12  and  14 . 
   The hinge plates  18 ,  20  are preferably generally curvilinearly shaped on their side edges along a pair of arcs coincident respectively with the arcs of pivotal movement of the arms  12 ,  14 . 
   The proximal end surfaces  26  of the two support arms comprise complementary, mutually engaging surfaces formed on arcs of curvature conforming to the polycentric movement between the arms  12 ,  14 , so that the two arms engage one another and derive mutual support and guidance one from the other throughout substantially the entirety of the arc of relative rotation of the arms. Consequently, forces imparted to the hinge  10  in the plane of the hinge are borne by the entirety of the hinge construction, including the abutting surfaces of the support arms, so that the integrity of the hinge  10  is not reliant solely on the hinge plates  18 ,  20  and pivot pins  22 ,  24 . 
   Further, to provide for continual interengagement of the components of the hinge for maintaining the same in predetermined engaged relationship with one another, the mutually engaging end surfaces of the arms are provided with gear teeth  60  which are intermeshed and engaged with one another in all positions of relative rotation between the arms. 
   For injured or injury prone knees that should not be permitted a normal range of movement, protection is provided by a range of motion adjustment means incorporated within the hinge assembly  16 . As shown, the hinge plates  18 ,  20  are provided with aligned pairs of angularly spaced limit stop receiving holes or apertures arranged concentrically about at least one and preferably both of the pivot pins  22  and  24 . The limit stop receiving holes are arranged in respective sets  30  for defining extension limit positions and sets  32  for defining flexion limit positions. The holes or apertures are adapted for reception therein of limit pins  28  which in the preferred embodiment are four in number, two for insertion in corresponding pairs of the two sets of extension limit holes  30  and two for insertions in corresponding pairs of the two sets of flexion limit holes  32 . While desired limits of extension and flexion could be established by a single set of extension limit holes  30  and a single set of flexion limit holes  32  and the use of just two limit pins  28 , the use of four sets of holes and four pins effectively doubles the strength of the motion limiting means, thereby to provide a very sturdy construction having a large number of limit positions without necessitating large or heavy duty limit stop pins and fewer limit positions. 
   The pins  28  are situated to be engaged in extension by the forward or front edges  12   a ,  14   a  of the arms  12 ,  14  and in flexion by the rearward or rear edges  12   b ,  14   b  of the arms  12 ,  14 . The limit pins  28  inserted in corresponding ones of the adjustment apertures  30  thus establish an adjustable range of relative arm rotation for extension, while the limit pins  28  inserted in corresponding ones of the adjustment apertures  32  establish an adjustable range of relative arm rotation for flexion. 
   Each limit pin is of a size and shape to pass through the selected aperture in hinge plate  18  and to extend into the space between the hinge plates to act as a barrier and limit further rotation of the arms in a given direction, i.e., by engagement therewith of the arms  12 ,  14 . In the preferred embodiment, the limit pins  28  are of a length to extend to and engage within corresponding aligned adjustment apertures provided in and through the hinge plate  20 , thereby protecting the limit pins from bending or jamming. The tops of the pins are domed, e.g., semi-spherical, to serve as cam surfaces when pin covers (to be described) are moved to closed position, thereby to fully and firmly seat the pins in the apertures in plates  18  and  20 . 
   By appropriate positioning of the limit or stop pins  28 , the hinge can accommodate complete flexion and/or complete extension of the knee, or can selectively limit the knee to one of several degrees of flexion and/or one of several degrees of extension, i.e., a limited range of motion, or the hinge can be locked in any one of several positions of fixed adjustment. Thus, the hinge provides for a protective or rehabilitative knee brace having universal adjustability. 
   The limit pins  28  are retained in association with the hinge assembly  16  by retainer means  34 , specifically a pair of pin retainers  34   a ,  34   b  each carrying a pair of the pins  28 . Each retainer comprises an elongate, string like central portion slideably extended around a respective one of the pivot pins  22 ,  24  and enlarged end portions each having an aperture therein for secure reception and retention of a respective one of the pins  28 . Preferably, each retainer carries an extension limit pin at one end thereof and a flexion limit pin at the other end thereof. The length and flexibility of the string like central portion facilitates convenient movement of the pins between the adjacent apertures and insertion of the pins into and removal of the pins from the apertures, all without risk of the pins being lost or misplaced. 
   The limit or stop pins  28  are preferably sized so as to be easily and slideably insertable into and removeable from the adjustment apertures or holes  30 ,  32 . Consequently, once the pins have been inserted into respective motion control or adjustment apertures or holes, it is desirable to provide a cover for the pins so they will not inadvertently become displaced from the selected holes. 
   In accordance with the invention, one or more cover elements  50  are mounted on the outer surface of the exterior hinge plate  18  for pin covering and uncovering movement in a plane parallel to the plane of the hinge plate. This provides a cover assembly that is resistant to inadvertent displacement of the cover element or elements during use of the hinge, particularly during use of the hinge in a knee brace that is utilized in the course of contact sports. Preferably, the cover element or elements  50  are pivotally or swingably mounted on a pivot pin or pins extending normal, i.e., substantially perpendicular, to the hinge plate so that the element or elements move parallel to the plate. 
   As shown in the drawings, a preferred embodiment of pin cover is comprised of a base plate  48  and a pair of “clam shell” cover elements  50 . The base is mounted on the outer surface of the exterior hinge plate  18  by the pivot pins  22 ,  24 . The base includes, on the interior surface thereof, a pair of spaced parallel pivot pins  52  that extend normal to the plane of the hinge plate  18 . Each cover element  50  is generally semi-circular in plan view and has a vertical marginal edge or sidewall  54  for enclosing the heads of the limit pins in the closed positions of the covers. At one pair of ends thereof, the cover elements have end portions  50   a  of reduced thickness that extend into the interior of the base  48  and are mounted, respectively, on the pivot pins  52 . Alternatively, the pivot pins  52  could be provided on the cover element for reception in apertures in the base. In a further and preferred alternative, the end portions  50 A of the cover elements have apertures in their upper surfaces for reception of pivot pins  52  on the base  48  and aligned pivot pins on their lower surfaces that are pivotally received in apertures  52 A in the upper or exterior hinge plate  18 A, thereby to securely mount the cover elements for pivotal movement between the base  48  and the hinge plate  18 . In all such structures, the cover elements are swingable toward and away from one another in a plane parallel to the hinge plate between closed and open positions to respectively cover and uncover the limit pins  28  and, in the closed position, to enclose the pins within the side walls  54  of the covers. 
   At the other pair of ends thereof, the cover elements  50  also have end portions  50   b  of reduced thickness which in the closed position of the covers are adapted to overlap one another and which, when overlapped, have aligned apertures  50   c  for reception of a latch pin for securely locking the covers in closed position. 
   In the preferred embodiment of the invention, the base  48  pivotally mounts a latch member  56  having a latch pin  58  for movement into and out of latching or locking engagement within the aligned apertures  50   c  at the said other ends  50   b  of the cover elements. The latch member  56  is pivotally mounted on an axis parallel to the plane of the hinge plate for pivotal movement in a plane normal to the hinge plates. In open or unlatched position, the latch member  56  extends upwardly from the base  48  to an out-of-the-way location to accommodate free access to and adjustment of the limit pins  28 . To retain the latch in the open or out-of-the-way location, the base of the latch member is preferably provided with a protrusion or bump that is received within a dimple in the hinge plate  18  to serve as a detent for holding the latch open. In closed and latched position, the latch member is of a length to extend to but not significantly beyond the marginal edges of the cover elements so that it may be manually manipulated with ease but without significant exposure to inadvertent or accidental displacement. Additionally, the latch member fits into a recess formed in the overlapping portions of the cover elements so as to be flush with the outer surfaces of and protected by the cover elements. Also, the latch member at its free end extends between converging curvilinear marginal edges of the cover elements to be further shielded against inadvertent or accidental displacement. 
   To facilitate assembly of the hinge, the component parts  18 A,  48 ,  50 ,  56 , and  34  (suitably with pins  28  in place) are preferably put together and formed into or a pre-subassembly that is held together by a rivet or similar fastener  60  that extends through aligned apertures in the base  48  and hinge plate  18 A. The cover elements  50  are thus pre-assembled for swinging or pivotal movement parallel to the plate  18 A. Also, the base  48  is provided in its lower surface with curvilinear grooves for reception of the central portions of the retainers  34  thereby to pre-mount the retainers between the base and the hinge plate for relative sliding movement about the respective pivot pins  22  and  24  to accommodate placement of the limit pins  28  in selected limit pin apertures  30  and  32 . 
   Should any of the limit pins  28  fail to be fully seated in their respective limit apertures, the covers  50  as they are moved to closed position will engage the domed tops of the pins and force them into fully seated positions in the plates  18 A and  20 A. 
   The cover elements, when closed and latched, completely enclose the limit pins and are effectively prevented from accidental opening, especially during use in contact sports, and therefore prevent accidental displacement of the limit pins and ensure that the knee brace remains at all times properly adjusted to the particular requirements of the wearer. 
   The objects and advantages of the invention have thus been shown to be attained in a convenient, practical, economical and facile manner. 
   While a preferred embodiment of the invention has been herein illustrated and described, it is to be appreciated that various changes, rearrangements and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.