Safety, efficacy and predictive factors of efficacy of a single intra-articular injection of non-animal-stabilized-hyaluronic-acid in the hip joint: results of a standardized follow-up of patients treated for hip osteoarthritis in daily practice.

Aim: To evaluate, in daily clinical practice, the efficacy and tolerability of a single intra-articular injection of non-animal-stabilized hyaluronic acid (NASHA) in patients treated for symptomatic hip OA (HOA).

Methods: Standardized follow-up (FU).

Patients: forty patients suffering from HOA treated by a single intra-articular injection of NASHA in the painful hip under fluoroscopy.

Evaluation: patient global assessment (PGA) and walking pain (WP) on a 100 mm visual analogue scale, WOMAC index, Lequesne index at each visit.

Statistics: last observation carried forward. Treatment efficacy was assessed using OMERACT-OARSI response criteria, minimal clinically important improvement (MCII), patient acceptable symptom state (PASS) obtained from PGA, WOMAC and WP. Predictive factors of efficacy were also studied.

Results: Efficacy evaluation: 34 patients were assessable (mean FU 159 days). All clinical variables (WP, PGA, WOMAC, Lequesne index) decreased significantly between baseline and last evaluation. Twenty-two patients (71%) were classified OMERACT-OARSI responders, 25 subjects (75.8%) were classified PASS+, and 19 (61.3%) fulfilled criteria for MCII. Out of clinical and radiological variables only Lequesne index (p = 0.04) and WOMAC (p = 0.04) at baseline were found to be predictive of treatment efficacy. Safety evaluation: the treatment was well tolerated. There were no severe adverse events related to the treatment or to the procedure. However 15 of the 28 assessable patients experienced transient increase of pain in the target hip during the first week after injection.

Conclusion: Viscosupplementation of the hip with NASHA is easily feasible in daily clinical practice, safe and well tolerated despite a frequent increase of pain the days following injection. Prospective controlled trials are needed to confirm these data and to evaluate both safety and efficacy of a second course of treatment.