Tibial plateau strength patterns in experimental modular knee replacement.

Nondestructive low-strain-rate compression tests were carried out on 12 human cadaver tibiae fitted with a metal modular resurfacing component on the medial or lateral condyle. The tests were done at 20 regularly spaced points on each plateau. The reproducibility of measurement was +/- 16% (95% tolerance limits). A statistically significant correlation was demonstrated between stiffness and ultimate force values obtained from the same points (r = 0.75, P less than 0.005). On the medial plateau the compressive stiffness of the system was maximal when load was applied to the center of the prosthesis, but declined sharply toward the medial and posterior margins. On the lateral plateau maximal stiffness values were obtained more posteriorly, and the stiffness gradients toward the periphery were less marked. Details of surgical technique and specific loading situations that may cause undesirable combinations of load and point of prosthetic component contact are discussed.