The study aim was to compare the efficacy and safety of ultrasound-guided intra-articular injections of hyaluronic acid and betamethasone in the management of patients with osteoarthritis of the thumb.

Eighty-eight evaluable patients diagnosed with osteoarthritis of the thumb (Kellgren-Lawrence grade II-III) received ultrasound-guided intra-articular treatment with hyaluronic acid (48) or betamethasone (40). In total, 3 local injections were scheduled at 7-day intervals. Assessments were performed at baseline and at 7, 14, 30, 90, and 180 days.

In both study groups, the pain Visual Analogue Scale and Functional Index for Hand Osteoarthritis scores decreased significantly during follow-up compared to baseline. There were no significant differences between the groups. However, at 90 days, the functional score showed a trend towards greater clinical improvement in the hyaluronic acid group (P 0.071). A subanalysis of patients with Functional Index score≥5 and Visual Analogue Scale score≥3 at baseline showed a significantly higher median functionality score in the hyaluronic acid group (P 0.005 at 90 days and P 0.020 at 180 days). Further limiting analysis to a baseline pain score≥5 showed significantly greater improvement in functionality score (P 0.004 at 180 days), which was already apparent after the second intra-articular injection at 14 days (P 0.028). In this patient subset, the mean pain score also improved significantly at 180 days (P 0.02).

Both hyaluronic acid and betamethasone were effective and well-tolerated for the management of rhizarthrosis. Hyaluronic acid was more effective over time and more efficiently improved functionality and pain in patients with more severe symptoms.