Structural joint changes, malalignment, and laxity in osteoarthritis of the knee

Objective: To assess the relationship between ( i) structural joint changes ( i. e. joint space narrowing and osteophyte formation) and laxity and ( ii) joint malalignment and laxity in osteoarthritis ( OA) of the knee. Methods: A cross- sectional study was carried out on 35 outpatients with osteoarthritis of the knee. Weightbearing radiographs of the knees were used to assess joint space narrowing ( JSN) and osteophyte formation. Knee joint laxity was assessed using a device that measures the angular deviation of the knee in the frontal plane ( varus - valgus laxity). Malalignment was assessed using a goniometer. All analyses were performed using knees as units of analysis ( i. e. 70 knees). Results: The mean laxity of 70 knees was 8.0 +/- 4.1 degrees. Knees with minute JSN were significantly more lax than knees with no JSN. There was no significant relationship between osteophyte formation and laxity. Malaligned knees were significantly more lax than aligned knees. Conclusion: Both joint space narrowing and malalignment are related to laxity. These results support the premise that biomechanical factors play a role in the degeneration of the osteoarthritic knee joint.