The "Thumbs-up" sign and trapeziometacarpal joint injection: a useful clinical indicator.

BACKGROUND: Several clinical studies investigating the accuracy and efficacy of trapeziometacarpal injection exist. Some studies utilize anatomical landmarks for proper injection placement while others utilize modalities including ultrasound and fluoroscopy. The changes of limb position that occur at the time of intra-articular injection can provide valuable visual and tactile feedback to the clinician. The purpose of this study is to investigate the occurrence of the "Thumbs-up" sign with injection of the thumb trapeziometacarpal joint as a useful and reliable clinical indicator of intra-articular trapeziometacarpal injection and correlate level and duration of pain relief.
METHODS: Trapeziometacarpal joint injections were performed on twenty-seven thumbs utilizing anatomic landmarks. At the time of injection, the presence or absence of the "Thumbs-up" sign was noted, and needle location was verified after injection with orthogonal mini-C arm fluoroscopic images. Visual analog pain scale scores were obtained pre-injection and by follow-up telephone calls at 1 week, 6 weeks, and 3 months post injection.
RESULTS: Twenty-four of twenty-seven injections demonstrated a positive "Thumbs-up" sign. There were three negative "Thumbs-Up" injections. The thumbs-up sign demonstrated a 92.3 % sensitivity. Eighteen of twenty-seven thumbs had sustained relief at 3 months post injection.
CONCLUSIONS: The "Thumbs-up" sign is a practical clinical tool that gives the practitioner important visual feedback at the time of injection. Patient relaxation and joint compliance are limiting factors. The "Thumbs-up" sign is an inexpensive indicator of successful intra-articular injection and may obviate the need and expense of advanced imaging modalities at the time of injection.