Comparison of Early-Stage Knee Osteoarthritis Induced by Medial Meniscus Tear Versus Tibial Osteotomy in the Rat Model.

OBJECTIVE

Medial meniscus tear (MMT) is a common method to induce osteoarthritis in rats, but mimics secondary osteoarthritis. A novel method of carrying out a medial wedge closing tibial osteotomy (TO) has been recently developed to induce primary osteoarthritis. This study aims to validate it, compared to MMT.

METHODS

Twenty rats were divided equally into 2 groups. Outcome measures such as histology graded according to Osteoarthritis Research Society International (OARSI) guidelines and computed tomography (CT) scans were analyzed at 6 weeks post-operatively. Observational gait analysis and serum biomarkers such as C-terminal cross-linked telopeptides of type II collagen (CTX-II) and -1 beta (IL-1β) were collected at 2-weekly intervals up to 6 weeks post-operatively.

RESULTS

Serum CTX-II and IL-1β levels did not reveal a statistically significant difference across all time points between the 2 groups. CT grading was significantly more severe (2.80 ± 1.10 vs 1.40 ± 0.548, = 0.0389) in the MMT group compared to the TO group. In addition, histological gradings such as calcified cartilage score (2.10 ± 1.91 vs 0.00 ± 0.00, < 0.01) and cartilage degeneration score (4.80 ± 5.18 vs 0.00 ± 0.00, < 0.01) revealed significantly more severe osteoarthritis in the MMT compared to TO group. Synovial membrane score did not reveal a statistically significant difference (1.10 ± 0.994 vs 1.00 ± 0.00, = 1.00).

CONCLUSION

TO is a novel method in inducing primary osteoarthritis in the rat model compared to MMT between the 6 and 12 weeks' time frame.