Purpose: The accuracy of intra-articular injection of the basal joint of the thumb and the rate of soft tissue extravasation of injected material in successful intra-articular injection was investigated. It was hypothesized that success of blind injections would approach that of fluoroscopically aided injection, and would approach the reported accuracy rates for injections of other joints.

Methods: Thirty cadaveric hands were injected with radio-opaque dye and examined fluoroscopically for accuracy of injection. To re-create the ideal situation, eight specimens were injected using a portable fluoroscopy unit to aid in needle placement. The remaining twenty-two specimens were injected without fluoroscopic aid in needle placement, thus approximating the conditions in most outpatient offices and clinics. The results were recorded in one of three categories depending on the location of the dye on post-injection fluoroscopic examination: 1) completely within the joint, 2) within the joint and the surrounding soft tissues, and 3) completely outside the joint.

Results: The rate of intra-articular accuracy for the fluoroscopically aided injections was 100% and the accuracy for the “blind” injection group was 81.8%. The rate for soft tissue extravasation of dye for successful intra-articular injections was 25% in the fluoroscopically aided group and was 33.3% for the “blind” group.

Conclusions: In the basal joint of the thumb, the accuracy rate for intra-articular injection without fluoroscopic guidance identified in this study is comparable to the accuracy rates reported for injection of larger joints, such as the knee. As was suspected, the accuracy of needle placement was improved by using portable fluoroscopic guidance. There is a relatively high soft tissue extravasation rate for successful intra-articular injection. These findings seem to validate intra-articular injection to deliver medication to the basal joint of the thumb as a viable treatment option. The relatively high rate of soft tissue extravasation, however, must be considered when the injection of materials that may adversely affect soft tissues is contemplated.