Articular cartilage lesions of the knee following immobilisation or destabilisation for 6 or 12 weeks in rabbits.

Eighty mature female New Zealand White rabbits were sacrificed 6 or 12 weeks after either section of the medial collateral and the anterior cruciate ligaments with removal of the anterior third of the medial meniscus of one knee, or immobilisation of one knee, using the contralateral non-treated knee as the control. The area of degenerated joint surface of the distal femur, and water and proteoglycan content were measured, and the articular cartilage stained using haematoxylin and eosin and safranin O. Destabilisation resulted in a significantly larger time-dependent degenerated joint surface area. Water content significantly increased after 6 weeks with no significant differences between immobilisation and destabilisation. Destabilisation resulted in a significantly greater decrease in proteoglycan content. At 12 weeks, the control knees of the animals undergoing destabilisation showed significant degenerative changes. There were more extensive lesions in destabilisation, while 6 weeks of immobilisation produced moderate degenerative joint disease.