The lateral compartment in knees with isolated medial and patellofemoral osteoarthritis: a histologic analysis of articular cartilage.

The purpose of this study was to examine, at a histologic level, the articular cartilage of the radiographically normal lateral compartment in knees with isolated medial and possibly patellofemoral osteoarthritis. Twenty patients with radiographic evidence of medial compartment osteoarthritis and a radiographically osteoarthritis-free lateral compartment underwent a tricompartmental total knee arthroplasty. The resected lateral femoral condyle and lateral tibial plateau were evaluated by a fellowship-trained musculoskeletal pathologist for the presence, or lack thereof, of osteoarthritis at a microscopic level. Both the tibia and femur showed evidence of mild osteoarthritis at a microscopic level. This study shows that in patients with radiographic evidence of medial osteoarthritis and a radiographically normal lateral compartment, there is mild osteoarthritis in the lateral compartment.