Overall tolerability and analgesic activity of intra-articular sodium hyaluronate in the treatment of knee osteoarthritis

Objective. Viscosupplementation with intra-articular hyaluronic acid (HA) is an alternative to the treatment of symptomatic knee osteoarthritis (OA) with pain relieving drugs. Sinovial*, is a sterile, non-pyrogenic 0.8% solution of highly purified sodium hyaluronate for intra-articular application. The aim of the present study was to investigate the safety and tolerability profile of this preparation in patients with symptomatic knee OA over 24 weeks. Research design and methods: This was a single group, open-label study, including outpatients of both sexes, aged between 18 and 85 years, with symptomatic knee OA. All patients underwent weekly intra-articular injections of HA for 5 consecutive weeks and were followed-up for 19 additional weeks. The safety and tolerability profile (primary endpoint) was assessed by adverse event (AE) reporting. The secondary endpoint was efficacy evaluated by changes in the Western Ontario and McMaster Universities (WOMAC) score vs. baseline. Patient and physician satisfaction were also recorded. Results: Intra-articular HA was generally well tolerated. The most frequent AE was pain at the injection site (5.8% of the injections); no serious treatment-related AE was reported. The WOMAC score was significantly reduced within the first 2 weeks of treatment (from 4.02 +/- 1.90 to 3.55 +/- 2.04, p = 0.0011), further decreased by the end of the injection series (week 6: 2.59 +/- 1.90; p < 0.0001) and maintained during the follow-up (week 24: 2.44 +/- 1.88; p < 0.0001). The WOMAC subscores were also significantly reduced from week 4 for 'pain' and from week 6 for 'stiffness' and 'physical function'. Conclusions: In the present study, intra-articular HA was well tolerated and safe in patients with symptomatic knee OA. Based on the sustained improvements in WOMAC score and subscores, a carry-over effect lasting for at least 19 weeks after the last injection may be proposed. These results further confirm the evidence of efficacy and safety of intra-articular HA in the management of knee OA.