Predictors of response to viscosupplementation in patients with hip osteoarthritis: results of a prospective, observational, multicentre, open-label, pilot study.

<bold>Background: </bold>To identify predictive factors of response to viscosupplementation (VS) in patients with hip osteoarthritis (HOA).<bold>Methods: </bold>Prospective, multicentre, open-label trial, achieved in daily practice conditions. Patients with HOA were treated with a single intra-articular injection of a cross-linked hyaluronic acid combined with mannitol (HAnox-M-XL), using imaging guidance. WOMAC pain and function scores and patient global assessment (PGA) were assessed at baseline and day 90. Improvement, satisfaction and efficacy were self-assessed at day 90. Hip radiographs at baseline were scored using Kellgren-Lawrence grade and Osteoarthritis Research Society International (OARSI) score. Associations between clinical and radiological features and response to VS (pain improvement > 50% at day 90) were assessed in univariate analysis, and then using logistic regression, adjusted for confounding factors.<bold>Results: </bold>The intent-to-treat (ITT) population included 97 patients (57 females, mean age 63). Ninety completed the follow-up and 80 had full clinical and radiological data. Response to VS was achieved in 47.8% of patients. In univariate analysis, the only clinical outcome statistically and negatively related to response was PGA at baseline (p = 0.047). Radiologically, response to VS was negatively correlated with joint space narrowing (JSN) score (JSN < 2 vs. JSN ≥ 2, p = 0.01) and was related to the patterns of femoral head migration (p = 0.008). In multivariate analysis, only JSN grade (p = 0.03) remained significantly related to a poor response.<bold>Conclusion: </bold>This pilot study, which needs further confirmation by larger scale trials, suggests that radiological features might be of importance for the decision of VS in patients with HOA.<bold>Trial Registration Number: </bold>ID RCB N°2013-A00165-40. Registered 31 January 2013. [ABSTRACT FROM AUTHOR]