Sodium hyaluronate in the treatment of osteoarthritis of the ankle: a controlled, randomized, double-blind pilot study.

Background: Intra-articular injections of hyaluronans have been shown to be safe and effective for the treatment of pain associated with osteoarthritis of the knee. This pilot study was undertaken to gather preliminary data on the efficacy and safety of five weekly intra-articular injections of Hyalgan (sodium hyaluronate; molecular weight, 500 to 730 kDa) as compared with saline solution for the treatment of pain associated with osteoarthritis of the ankle.

Methods: Twenty patients at two test sites were randomized with use of a double-blind (blinded observer), saline solution-controlled, parallel experimental design. Patients were randomized to receive five weekly intra-articular injections of either 1 mL of sodium hyaluronate (10 mg/mL) or 1 mL of phosphate-buffered saline solution into the ankle joint. The primary outcome measurement was the ankle osteoarthritis score. Several secondary outcome measures also were assessed.

Results: Significant improvement in the mean ankle osteoarthritis score from baseline was seen at all follow-up visits from one to six months in both the sodium hyaluronate group and the saline solution group (p < 0.0001). In addition, five of nine patients in the sodium hyaluronate group had >30 mm of improvement in this score, compared with one of eight patients in the control group. No withdrawals were directly attributable to the injections of sodium hyaluronate or saline solution, and no severe medication-related adverse events were observed.

Conclusions: The present study suggests that five weekly intra-articular injections of sodium hyaluronate (molecular weight, 500 to 730 kDa) are well tolerated, can provide sustained relief of pain, and can improve function in patients with osteoarthritis of the ankle. These findings are consistent with those of previously published studies involving intra-articular injections of sodium hyaluronate in other joints, but they require confirmation in a large, randomized, saline solution-controlled study.