In vivo kinematics of the rabbit knee in unstable models of osteoarthrosis.

The effects of osteoarthrosis inducing surgery on the kinematics of the rabbit knee were evaluated in vivo. A video motion analysis system was used to track reflective markers attached to two pins fixed in both femur and tibia, and from these data knee kinematics were computed. The control for all measurements was the gait after pins were implanted, but the knee was unaltered. Both a release of the anterior cruciate ligament and a partial medial meniscectomy were then performed, and the animals' gait was recorded at 4, 8 and 12 weeks after knee surgery. Knee kinematics were described by three translations and three rotations and were analyzed in terms of maximum and minimum values and range of motion. Statistical comparisons of these data between control and operated knees were made using Wilcoxon's signed rank test. Results showed an initial increase in maximum anterior displacement which returned to normal after 12 weeks. In addition there was a persistent increase in knee adduction and an increase in the minimum value of external rotation over the 12 week period. At 12 weeks after surgery there was no change in range of any measurable kinematic parameter. Overall, the changes in joint kinematics following partial medial meniscectomy and release of the anterior cruciate ligament were small, suggesting that altered joint kinematics might not be a critical factor in the development of osteoarthrosis in this animal model.