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

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.

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.

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.

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.

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