WEAR PATTERNS ON TIBIAL PLATEAUS FROM VARUS AND VALGUS OSTEOARTHRITICKNEES

The size and location of articular cartilage wear was assessed on 106 varus and 37 valgus osteoarthritic tibial plateaus resected during tot al knee arthroplasty, Anterior cruciate ligament integrity was assesse d intraoperatively, and calibrated digital images were used to measure the wear patterns. Complete anterior cruciate ligament deficiency was seen in 25% of the varus and 24% of the valgus knees. Wear patterns o n anterior cruciate ligament intact and attenuated varus tibial platea us occurred in the middle to anterior aspect of the medial plateau, An terior cruciate ligament deficient varus plateaus had significantly la rger wear areas located more posterior on the medial plateau, In contr ast, anterior cruciate ligament intact and deficient valgus tibial pla teaus had wear located posterior to the center of the lateral plateau, Anterior cruciate ligament integrity is a discrete feature of advance d osteoarthritis that strongly influences the articular wear patterns. The anterior cruciate ligament deficient wear patterns show a wear me chanism that is consistent with the posterior femoral subluxation and posterior tibiofemoral contact observed after acute anterior cruciate ligament rupture. These observations provide insight into the altered knee mechanics that exist in osteoarthritic knees and the resulting me chanical factors that contribute to degenerative changes.