Efficacy of a single intra-articular injection of ultra-high molecular weight hyaluronic acid for hip osteoarthritis: a randomized controlled study

Background: Viscosupplementation with hyaluronic acid (HA) is increasingly used for the treatment of hip osteoarthritis (OA). The purpose of this study was to compare the efficacy of intra-articular injections of an ultra-high molecular weight viscosupplement (UHMW-HA, Fermathron S) with a medium molecular weight hyaluronan (MMW-HA, Hyalubrix 60) in hip OA. Methods: Fifty-four patients with hip OA grade 3 on the Kellgren/Lawrence scale were randomized. All infiltrations were performed under ultrasound guidance. Evaluation was performed preoperatively and at 1, 3, 6 and 12 months after infiltration. Patients were clinically evaluated using Lequesne index, VAS and WOMAC score. Results: Fifty patients, including 27 in the MMW-HA group and 23 in the UHMW-HA group, completed the follow-up. No significant difference was found between the two groups in terms of VAS, WOMAC or Lequesne index preoperatively or at 1, 3, 6 and 12 months after viscosupplementation. A stratified analysis was performed to study the development over time of Lequesne index of patients aged ≤ 55 years, > 55 and, ≤ 70 years and > 70 years and Lequesne index was different between the three age-stratified subgroups only in the MMW-HA group. The subgroup of older patients showed a higher Lequesne index than the subgroups of younger patients (p < 0.05). Conclusions: UHMW-HA is a safe and effective treatment for hip osteoarthritis. A single dose of UHMW-HA was as effective as two doses of MMW-HA resulting in similar reductions of pain and disability. Study design: Multicenter, independent, prospective, randomized controlled trial with level of evidence 1.