Letter regarding "The Efficacy of Intra-Articular Versus Extra-Articular Corticosteroid Injections in the Thumb Carpometacarpal Joint"

We read the article “The Efficacy of Intra-Articular Versus Extra-Articular Corticosteroid Injections in the Thumb Carpometacarpal Joint” by Katt et al with great interest, as optimal placement of steroid injections in the thumb carpometacarpal joint is intensely discussed among hand surgeons. Our own clinical experience shows that there is no evident difference in pain reduction between extra- and intra-articular injections. Although we were pleased to see a scientific investigation addressing this topic, we were nonetheless surprised by the study conclusion that intra-articular injections provide significantly lower pain and Disabilities of the Arm, Shoulder, and Hand (DASH) scores compared with extra-articular injections at 3 months (P < .05). We believe some scientific shortcomings markedly influenced the results. Patients were allocated to intra- and extra-articular groups post hoc: that is, according to the final location of steroid deposition. Accompanying interventions, including pain medication and orthotic or hand therapy, were also not standardized. Yet, these interventions seem to be effective and could, therefore, influence the outcome of steroid injection therapy. Another concern is the interpretation of differences in DASH and visual analog scale pain scores at 3 months. Although statistical testing revealed significant P values, the group differences in DASH and pain scores were smaller than the minimal important difference (MID); the MID ranges between 10 and 19 points for the DASH and between 1.3 and 2.1 points, on a numeric rating scale, for pain at rest.^{,  ,}  Therefore, the clinical relevance of the group differences is questionable and the significant P values could, in fact, be because of chance or other, unscreened factors.

Overall, we question the generalizability of the newly published results and propose further examination, in a randomized controlled trial, of the highly interesting question of whether intra- or extra-articular steroid injections are more effective in treating thumb carpometacarpal joint arthritis. In such a study, administration of injections should be done under fluoroscopic control, additional therapies should be standardized, and a statistician should be involved for high-quality data analysis.