Increasing Concentration of Sinovial: Effect on Cartilage Protection in a Rabbit ACLT Model

Objective This study aimed to test the hypothesis that administration of increasing doses of Sinovial (hyaluronic acid [HA]), would exhibit a dose-dependent effect on the prevention of cartilage degradation, without local and systemic toxicity. Methods Twenty-seven adult rabbits were subjected to anterior cruciate ligament transection (ACLT). Two Sinovial products containing HA concentrations of 1.6% and 2.4% were used as active treatment, and 0.9% saline was used as control and injected intra-articularly 7 days post ACLT. Radiographs were taken prior to surgery, at injection and sacrifice times. After euthanasia, 8 weeks postsurgery, knee joints were observed macroscopically using India ink staining with OARSI (Osteoarthritis Research Society International) scoring and histologically using modified Mankin scoring. The synovial membranes were analyzed using Cake classification. Results No intraoperative complications were observed. One week postinjection, 4 animals in the HA 2.4% group developed subcutaneous nodules that disappeared spontaneously. No inflammation of the synovial membrane was ever observed. The control group exhibited the maximum uptake of India ink 2.22 ± 0.14. HA groups exhibited a dose-dependent ( P = 0.02) reduction in India ink uptake: 1.75 ± 0.17 for HA 1.6% and 1.58 ± 0.14 for HA 2.4%. The most marked dose-dependent effect of this study was a reduction of modified Mankin score for HA groups, with the 2.4% treatment achieving a statistically significant improvement as compared with the control group (7.19 ± 0.85 for saline, 4.65 ± 0.66 for HA 1.6%, and 3.53 ± 0.59 for HA 2.4%; P = 0.005). Conclusions A dose-dependent protective effect on cartilage was observed after injection of both HA solutions.