Intra-articular zoledronic acid in a rat osteoarthritis model: significant reduced synovitis may indicate chondroprotective effect.

Purpose: The aim of this experimental study was to evaluate the effect of intra-articular application of zoledronic acid (ZA) on joint cartilage and synovial tissue following induction of knee osteoarthritis (OA) in a rat model.

Methods: An OA model was created by anterior cruciate ligament transection (ACLT) in the right knees of 48 adult Wistar albino rats. The rats were randomized into a study and control groups, each including 24 rats, and 10 μg of ZA was injected in 0.1 ml of sterile saline to 24 animals in the study group on the first day to operation and was repeated weekly until the rats were killed. The same volume of sterile saline was injected with the same schedule to the control group. Eight rats from both the study and control groups were killed, each time, on the 4th day, the 3rd week, and the 6th week after the operation. The groups were compared based on the histological scores of synovitis and cartilage destruction and the evaluation of serum markers.

Results: Histological score indicates progression of synovitis was significantly less in the study group (p = 0.047). There was significant increase in the mean Mankin cartilage damage score in the control group (p = 0.021), while no significant change was found in the study group. When the two groups were compared over time, no statistically significant difference was detected in total histological scores, although there was a 47 % less incidence of cartilage tissue damage in the study group and better cartilage structure and tide mark integrity scores were also detected in the study group (p = 0.017 and p = 0.021, respectively).

Conclusion: Intra- articular zoledronic acid may suppress synovial inflammation. Furthermore, Zoledronic Acid does not reduce cartilage degeneration in early osteoarthritis models, but may provide some chondroprotective effect in ACLT- induced knee osteoarthritis model in rats.