System and method for side insertion of a bicondylar mini knee implant

Abstract

A bicondylar knee implants with improved fixation means for resurfacing only the weight-bearing surface of the femoral medial and lateral condyles, while preserving the cruciate ligaments and avoids displacing the patella. The inventive device includes metallic convex articular surfaces for resurfacing the medial and lateral femoral condyles, and concave multifacial non-articular surfaces to be affixed to the resected distal surfaces of the femur. The prosthesis provides claws situated at the anterior and posterior ends of the medial and lateral metallic condyles, which will firmly attach the implant against the resected femoral condyle. The prosthesis is designed to be implanted through a direct lateral approach and does not resurface the femoropatellar joint. Furthermore, a minirobot or electromechanical actuator is used to perform the femoral and tibial bone cuts using electromagnetic bone chipper.

1 . An implantable bicondylar femoro-tibial prosthetic device adapted to be implanted by lateral insertion through a direct lateral approach to a retropatellar region of a knee joint and for forming a joint between a femur and a tibia, the prosthetic device comprising:
 a biconylar femoral component having a thin shell convexly curved outer articular surface having a medial condyle having two ends, a lateral condyle having two ends, and an intercondylar anterior connection connecting the medial condyle to the lateral condyle and a concave non articular inner surface having retaining claws situated at each anterior ends and each posterior ends of the medial condyle and the lateral condyle, wherein, when the prosthesis is implanted on the weight bearing portion of the femur, the outer surface of the convexly curved articular surface is sized to substantially cover only the weight bearing portion and to substantially cover no portion of the patello-femoral joint of the knee, and wherein the concave non-articular inner surface consists of two or more substantially planar surfaces, and   wherein during the implantation of the fermoral component onto a resected portion of the femur by lateral insertion, the retaining claws are embeddable within a laterally resected surface of the femur; and wherein only the weight bearing portion of the femur is resurfaced by the lateral resection, which weight bearing portion is substantially defined by the articular surface of the femur which contacts the tibia of the knee joint during flexion from full extension through flexion.   
     
     
         2 . The prosthetic device of  claim 1 , wherein the retaining claws each include two planar sides extending from the non-articulating inner surface, and wherein the two planar sides converge to form a sharp edge. 
     
     
         3 . The prosthetic device of  claim 1 , wherein the retaining claws each include two planar sides extending from the non-articulating inner surface, and wherein the two planar sides are substantially parallel to each other and form a blunt edge. 
     
     
         4 . An implantable prosthetic device adapted to be implanted by lateral insertion through a direct lateral approach to a retropatellar region of a knee joint, and for forming a knee joint between a femur and a tibia, the prosthetic device comprising:
 a bicondylar femoral component having a concave non-articular inner surface and a curved articular portion including a medial condyle having two ends, a lateral condyle having two ends, and an intercondylar bridge connecting the medial condyle to the lateral condyle, and an inner surface including four retaining claws, one of each claws at said ends of the medial condyle and lateral condyle, and wherein the concave non-articular inner surface consists of two or more substantially planar surfaces;   a tibial component having a tibial metallic platform which has a bottom surface which includes an anterior and posterior retaining claws, and, a top surface which includes at least two restraining lips, and a polyethylene insert having a top surface, having two circular depressions, and a bottom surface having includes transverse retaining ridges configured to be fitted between the at least two restraining lips;   wherein, during the implantation of the femoral component onto a resected portion of the femur by lateral insertion, substantially no portion of the outer surface of the prosthesis resurfaces any area of the patello-femoral joint, and, during which insertion the four retaining claws are embeddable into the femur;   wherein during the implantation of the tibial metallic platform onto a laterally resected portion of the tibia by lateral insertion. during which insertion the anterior and posterior transverse retaining claws are adapted to both guide the tibial platform along a laterally resected surface of the tibia and to hold onto the tibia; and   wherein the polyethylene insert is adapted to be affixed to the tibial metallic platform by lateral insertion wherein the during which insertion the transverse retaining ridges the restraining lips of the tibial platform and is ultimately restrained upon of the top surface of the tibial metallic platform.   
     
     
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         21 . An implantable bicondylar femoro-tibial prosthetic device adapted to be implanted by lateral insertion through a direct lateral approach to a retropatellar region of a knee joint and for forming a joint between a femur and a tibia, the prosthetic device comprising:
 a biconylar femoral component having a convexly curved outer articular surface having a medial condyle, a lateral condyle, and an intercondylar anterior connection therebetween, and a concave non articular flat inner having extending outwardly therefrom a first mini post extending from the medial condyle and a second mini post extending from the lateral condyle, wherein, when the prosthesis is implanted on the weight bearing portion of the femur, the outer surface of the convexly curved articular surface is sized to substantially cover only the weight bearing portion and to substantially cover no portion of the patello-femoral joint of the knee, and   wherein during the implantation of the fermoral component onto a resected portion of the femur by lateral insertion, each of the mini posts are embeddable within a laterally resected surface of the femur; and wherein only the weight bearing portion of the femur is resurfaced by the lateral resection, which weight bearing portion is substantially defined by the articular surface of the femur which contacts the tibia of the knee joint during flexion from full extension through flexion.   
     
     
         22 . The prosthetic device of  claim 21 , wherein one or both of the miniposts have flat ends adapted to be penetrated into cancellous bone. 
     
     
         23 . The prosthetic device of  claim 21 , wherein one or both of the miniposts have curved ends adapted to be penetrated into cancellous bone. 
     
     
         24 . The prosthetic device of  claim 21 , wherein one or both of the miniposts have pointed ends adapted to be penetrated into cancellous bone.