Tibiofemoral contact pressures in degenerative joint disease.

Using tibiofemoral joints from older (age, 53-80 years) human cadavers with articular cartilage degeneration, contact pressures and contact areas were measured in the extended knee in four conditions: (1) neutral alignment; (2) 5 degrees varus (simulating single limb stance of gait); (3) 5 degrees valgus; and (4) after a 5 degrees proximal tibial closing wedge valgus osteotomy. In degenerated cartilage, contact pressures were reduced at the lesion sites and were high on the borders of the lesions. No statistically significant changes occurred in contact pressures and areas when values from neutral loading were compared with values during loading in each of the other three conditions. Lateral average and maximum contact pressures were less in varus loading than in valgus loading. Equal medial and lateral contact pressures during varus loading, in contrast to lower medial than lateral contact pressures in the other three loading, supports the theory that the varus moment imposed on the knee in single limb stance could be a mechanism causing medial tibiofemoral osteoarthritis. The 5 degrees valgus osteotomy resulted in contact pressures similar to those in neutral loading. These experiments do not support the value of the 5 degrees valgus osteotomy in reducing contact pressures on the medial tibial plateau.