Viscosupplementation with hyaluronic acid (HA) or its derivatives for the symptomatic relief of osteoarthritis (OA) of the hip joint has never been studied in placebo-controlled, double-blinded trials and conflicting results have been obtained from the published open trials. The aim of this study was to review the literature on viscosupplementation as a symptomatic treatment of hip OA.
Clinical trials in Medline (1966-2005) and Cochrane Controlled Trials Register using the key words: hip osteoarthritis AND hyaluronic acid or HA preparation trade name. All trials aimed to assess intra-articular hyaluronic acid injection for the treatment of hip OA were analyzed. In the absence of placebo-controlled trials, and because of the very wide variety of the study designs it was not possible to apply strictly the conventional rules of meta-analysis.
Nine studies, including a total of 287 patients, were identified. Eight studies were uncontrolled-open trials. One was a randomized double blind study comparing two HA preparations. Five open-label prospective studies, including a total of 141 patients with symptomatic hip OA, assessed the safety and efficacy of 1 to 3 x 2mL intra-articular (IA) injections of hylan G-F 20 under fluoroscopic or ultrasound guidance. The overall success rate was about 50% at 3 to 12 month follow-up. In 31 subjects with symptomatic hip OA who received 1 x 3mL IA injection of non animal stabilized hyaluronic acid (NASHA) under fluoroscopy, pain and disability were reduced by 59% and 47% respectively at month 3. Six to 11 months after treatment the results remained satisfactory (42% and 39%). Hyaluronan injections, performed 3 to 5 times at weekly intervals in 44 patients, were effective in controlling pain in 68% of the patients over the 6 month follow-up period. In contrast, 1 to 3 ultrasound guided IA injections of HA preparations with 0.5-0.75 or 1.0 million MW induced only a very weak benefit in 28 patients. In all studies IA injections of HA were safe and well tolerated. Transient pain at the injection site and mild increase in hip pain for a few days was more frequent with NASHA. In the only double blind controlled trial no difference between hyaluronan and hylan was found regarding both efficacy and safety.
To date, in the absence of placebo-controlled studies, the efficacy of IA injections of HA or its derivatives in the symptomatic treatment of hip OA cannot be determined conclusively. Nevertheless the published data suggest that viscosupplementation may be effective. Double-blind, controlled studies are required to confirm these data, before viscosupplementation should be included into the treatment paradigm for patients with hip osteoarthritis.