A one-year, randomised, placebo (saline) controlled clinical trial of 500-730 kDa sodium hyaluronate (Hyalgan) on the radiological change in osteoarthritis of the knee.

The primary objective of this study was to investigate structural changes, as measured by joint space narrowing (JSN), within the knee joint during treatment with intra-articular sodium hyaluronate (HA) of molecular weight 500-730 kDa in patients with osteoarthritis (OA) of the knee. Patients received a weekly intra-articular injection of either 20 mg2/ml HA or a 2 ml vehicle placebo (saline) for three weeks. This course was repeated twice more at four-monthly intervals. Concomitant treatment with analgesics or NSAIDs was allowed. The primary efficacy measure was the reduction in mean joint space width (JSW) of the medial compartment at 52 weeks. A total of 408 patients were randomised and 319 completed the one-year study (HA: n=160, placebo: n=159); 273 of the 319 were included in the primary analysis. Analysis of variance on these 273 patients did not show a statistically significant difference between the two treatment groups. However, there was a significant difference in response to treatment in terms of the baseline JSW (p=0.01), indicating that outcome of treatment may depend on-baseline JSW. Therefore, a subgroup analysis by baseline JSW was conducted. This compared patients with a JSW >4.6 mm with those with a JSW <4.6 mm. In those with radiologically milder disease at baseline and receiving HA, the JSN was significantly reduced compared with placebo (p=0.02). In patients with radiologically more severe disease there was no difference in JSN between the two treatments. Although, in this one-year study, no overall treatment effect was seen, those with radiologically milder disease at baseline had less progression of joint space narrowing when treated with HA.