Adjustable intramedullary replacement of the knee: evolution of surgical technique and prosthesis.

The total knee replacement developed at the New York Orthopaedic Hospital is a nonhinged, nonconstrained variety in which the principle fixation mechanism is via the intramedullary stems of both components. The plastic segment (high density polyethylene) is press fitted into the metallic component of the tibial segment to minimize "plastic flow" and deformity. The operative technique calls for conservation of the bone of the proximal tibia by a minimum of bone resection following complete soft tissue release including removal of the cruciates. Accuracy of replacement becomes possible when the cruciate ligaments are excised and the mediolateral soft tissue structures are balanced in tension following maximum spacing of the joint to provide stability. Provisions are made for routine replacement of the patellofemoral joint.