Single intra-articular injection of high molecular weight hyaluronic acid for hip osteoarthritis

BACKGROUND: Intra-articular (IA) injection of hyaluronic acid (HA) into the hip joint appears to be safe and well tolerated but only a small number of randomized clinical trials in humans has been published. The objective of this prospective study was to evaluate the efficacy and safety of a single IA injection of high-molecular-weight (2800 kDa) HA (Coxarthrum) for hip osteoarthritis. MATERIALS AND METHODS: All patients received a single IA administration of 2.5 % sodium hyaluronate (75 mg/3 mL) of high molecular weight. Fluoroscopy requires an iodized contrast medium (iopamidol, 1 ml) which highlights the capsule before administering HA. Patients were evaluated before IA injection (T0), after 3 months, after 6 months and after 1 year from injection. Results were evaluated by the Brief Pain Inventory (BPI II), Harris Hip Score and a visual analog scale of pain (pain VAS). All treated patients were considered for statistical analysis. RESULTS: Two hundred seven patients were included at T0. The mean age was 67 years (range 46-81). Regarding BPI severity score, changes in pain between T0 and the three following visits were statistically highly significant (p < 0.001). Changes in pain score compared to the previous visit were statistically significant for the worst pain in the second quarter post-intervention (p = 0.037) and for mean pain in the second semester post-intervention (p = 0.043) The evolution of the Harris Hip Score was statistically highly significant (p < 0.001) between T0 and the following visits (T0 + 3 months, T0 + 6 months and T0 + 12 months); after a significant change between T0 and T0 + 3 months, the score remained stable. The evolution of the pain VAS showed a statistically highly significant improvement (p < 0.001) between T0 and T0 + 3 months; thereafter it remained stable from the first quarter post-intervention. No serious adverse event was noted; 12 cases (0.5 %) of pain associated with transient synovitis are noteworthy. CONCLUSION: This study shows that a single IA injection of Coxarthrum is effective from the third month and that the results are stable or continue to improve up to 1 year. LEVEL OF EVIDENCE: IV.