The role of excessive body weight and meniscal instability in the progression of osteoarthritis in a rat model.

Background: The main objective of the study was to determine if excessive body weight and meniscal destabilization cause knee articular cartilage damage and changes in meniscal histology indicative of knee osteoarthritis (OA).

Methods: Forty female Lewis rats were randomly assigned to regular diet sham surgery, regular diet medial meniscus destabilization (DMM) surgery, high-fat diet sham surgery, or high-fat diet DMM surgery. Surgical intervention occurred four weeks after diet initiation. Rats were sacrificed four weeks post-surgery. Progression of OA was evaluated in femoral condyles and tibial plateaus using the Osteoarthritis Research Society International (OARSI) scoring system by two blinded scorers. Ossification of menisci was evaluated with digitized histological slides using a grid.

Results: DMM surgery had greater OARSI scores than sham surgery for all knee surfaces in both diet groups (all P < 0.004). The high-fat diet sham surgery group had greater OARSI scores than the regular diet sham surgery group on all knee surfaces (all P < 0.02). Histological evaluation showed the lateral meniscus had more bone than the medial meniscus, but there was no relationship between diet or surgery groups and amount of bone in the meniscus.

Conclusions: Results suggested excessive body weight may contribute to spontaneous onset of OA and emphasized the importance of preventative care in those at risk of developing OA.