In vitro contact stress distribution on the femoral condyles.

Contact stress distributions were measured across the tibiofemoral joints of 11 fresh-frozen normal cadaver specimens. Local stress magnitudes were sensed by arrays of miniature piezoresistive transducers inset superficially in the cartilage of the femoral condyles. Knee joints were tested at 0, 10, 20, and 30 degrees of flexion and later retested at 0 degrees following medial and dual meniscectomies. For the intact joint, both the spatial mean and peak local contact stresses rose approximately linearly with the joint resultant, reaching levels of 2.6 and 8.0 MPa, respectively, at 3 kN of applied loading. Flexion angle variations in the range studied failed to cause significant changes in the major contact parameters. Although meniscectomies involved contact area reductions and consequent stress increases, such effects were more moderate than results previously seen for static loading of the tibial plateau.