The Efficacy of Intra-Articular Versus Extra-Articular Corticosteroid Injections in the Thumb Carpometacarpal Joint.

Purpose: This study evaluated whether the location of steroid deposition (intra-articular vs extra-articular) for thumb carpometacarpal (CMC) joint arthritis affects clinical outcomes. Methods: We prospectively enrolled 102 hands (82 patients) with thumb CMC joint arthritis. Patients received a CMC joint injection with Triamcinolone and radiopaque contrast. Wrist radiographs were used to visualize the injection location. Patients completed Disabilities of the Arm, Shoulder, and Hand Questionnaire (DASH) questionnaires and visual analog scale (VAS; scale, 1-100) pain scores before injection and then at 1 week and 1, 3, and 6 months after injection. Generalized linear regression models were constructed to identify variables associated with clinical outcomes. Results: The rate of intra-articular injection was 80%. No differences were found between the 2 groups in preinjection DASH or VAS scores. After 1 week, both the intra-articular and extra-articular groups showed improvements of DASH (14.2 and 11.2, respectively) and VAS (15.5 and 15.0, respectively) scores. Although both groups were worse at 3 months, the intra-articular group had significantly lower DASH (26.7 vs 37.5, respectively) and VAS (26.5 vs 39.0, respectively) scores than the extra-articular group. There were no differences between the intra-articular and extra-articular groups for DASH (33.8 vs 42.5, respectively) or VAS scores at 6 months. The intra-articular group maintained significant improvements in outcomes for up to 6 months, while the extra-articular group only maintained them for up to 1 month. The Eaton-Littler classification was found to be a predictor of DASH and VAS scores at 3 and 6 months. Conclusions: Intra-articular injection in the thumb CMC joint provides significantly greater pain relief and functional improvement compared to extra-articular injection at 3 months. Inadvertent extra-articular injection is common and appears to provide short-term pain relief and functional improvement. Some patients receiving intra-articular injections continue experiencing relief for up to 6 months. Type of study/level of evidence: Therapeutic II.