[Efficacy and safety of a single intra-articular injection of 2% hyaluronic acid plus mannitol in knee osteoarthritis over a 6-month period].

OBJECTIVE To evaluate the safety and efficacy of a single intra-articular injection of 2% hyaluronic acid (HA)+mannitol in symptomatic knee osteoarthritis (KOA). MATERIAL AND METHODS Pilot, multicentre, open, non-comparative study performed in eighty patients with painful KOA, of whom 79 completed the study. They received one injection of 2ml of 2% HA+0.5% mannitol (Day 0) and were followed-up for 6 months. On Days 0, 15, 30, 60, 90, 120, 150 and 180, pain and joint function were assessed using a visual analogue scale (VAS) and WOMAC index. Efficacy and safety by investigator and patient, and rescue medication, as an indirect measure of pain, were also recorded. RESULTS A significant reduction in joint pain, stiffness and functional disability compared with baseline was observed at every follow-up visit (P<.001). Joint function improved by 38.7% on Day 30, reaching 47.5% on Day 180. Rescue medication use decreased from 58.2% at baseline to 2.5% on Day 90, increasing in the last visits. Efficacy and safety were positively evaluated by investigators and patients. No serious adverse events were observed. Mild side effects were reported in 4 patients (local pain and swelling in the infiltration area). DISCUSSION There is evidence that repeated intra-articular injections of HA improve symptoms in KOA. However, studies with a single injection of HA have shown mixed results. This study demonstrates that one single intra-articular injection of non-cross-linked HA reduces joint pain and increases function in patients with KOA over a period of at least 6 months.