Eloisa Velasco, Mª Victoria Ribera, Joan Pi

Osteoarthritis of the trapeziometacarpal (TMC) joint of the thumb - also known as rhizarthrosis - is painful and has a significant impact on quality of life. Intra-articular injection of hyaluronic acid may potentially meet the need for effective, minimally invasive intervention in patients not responding adequately to initial treatment. We aimed to confirm the safety and effectiveness of viscosupplementation with Durolane (NASHA nonanimal hyaluronic acid) in rhizarthrosis. This was a prospective, single-arm, multicenter, open-label study with a 6-month follow-up period. Eligible patients had Eaton-Littler grade II-III rhizarthrosis in one TMC joint with pain and visual analog scale (VAS) pain score ≥4 (scale: 0-10). A single injection of NASHA was administered to the affected TMC joint. The primary effectiveness variable was change from baseline in VAS pain score. Thirty-five patients (mean age 60.8 years; 85.7% female) received NASHA and completed the study. The least-squares mean change from baseline in VAS pain score over 6 months was -2.00, a reduction of 27.8% (p<0.001). The reduction in pain exceeded 25% as early as month 1 (26.5%), and gradual improvement was observed throughout the 6-month follow-up period. Secondary effectiveness parameters included QuickDASH (shortened version of Disabilities of the Arm, Shoulder, and Hand [DASH]), Kapandji thumb opposition test, radial abduction, metacarpophalangeal (MCP) joint flexion, and pinch (clamp) strength. Most of these measurements showed statistically significant improvements from baseline over 6 months. Five adverse events (injection site reactions) were reported in four patients (11.4%), and there were no serious or allergic reactions. This study suggests that viscosupplementation using NASHA is effective and well tolerated in treating the symptoms of rhizarthrosis.