Simultaneous changes in bone mineral density and articular cartilage in a rabbit meniscectomy model of knee osteoarthrosis

Objective: It was hypothesized that increased bone mineral density of the medial proximal tibia would precede or coincide with the development of more severe cartilage changes after meniscectomy. Methods: In a rabbit knee model, mineral density of subchondral bone and changes of articular cartilage were monitored 13 to 40 weeks after medial meniscectomy or a sham operation. Results: Both procedures resulted in a decrease of bone mineral density, especially of the medial proximal tibia, which persisted up to 40 weeks (P<0.02-0.0007). Meniscectomy induced cartilage changes typical for osteoarthrosis (P<0.009), which progressed over time on the posterior aspect of the medial tibial plateau (P<0.009), which is physiologically covered by the meniscus, but the procedure also induced iatrogenic changes which were located mainly on the anterior aspect of the concerned compartment, and which did not progress or develop to osteoarthrosis. Conclusions: The data suggest that the cartilage changes after meniscectomy in this animal model are caused by the surgical trauma, subsequent limb misuse, and altered load distribution, and initially associated by a decrease not an increase in bone mineral density of the proximal tibia. Moreover, the cartilage changes progressed without a simultaneous increase of the bone mineral density at corresponding sites. (C) 2000 OsteoArthritis Research Society International.