The effect of hyaluronic acid on a rabbit model of full-thickness cartilage repair

The current study investigated whether hyaluronate exerts a beneficial effect on articular cartilage repair. Nineteen rabbits had bilateral knee arthrotomies, and 2-mm full-thickness cartilage defects were created on each medial femoral condyle. Rabbits received intraarticular injections (0.5 mL) of hyaluronic acid once a week for 3 weeks in the right knee, started at either 1 or 3 weeks after injury. The left knees, which served as controls, were injected with 0.5 mL normal saline. Cohorts of each group were euthanized at 2 and 6 months, and histologic sections of the injury sites were evaluated for repair tissue. No significant differences were seen in the quantity or quality of the repair tissue at either 2 or 6 months. Hyaluronate and saline-treated defects showed persistent fibrillation, poor matrix staining, and incomplete void filling, irrespective of the injection timing. Hyaluronate did not provide protection to zones peripheral to the injury site, and did not significantly alter the healing process in this model of acute full-thickness cartilage injuries.