Sonographically guided tendon sheath injections are more accurate than blind injections: implications for trigger finger treatment.

OBJECTIVES: Trigger finger is frequently treated with tendon sheath injections. This cadaveric study evaluated the accuracy and safety of blind and sonographically guided tendon sheath injections. To our knowledge, a study that precisely mapped the locations of material injected into the tendon sheath has not been reported previously.

METHODS: A total of 40 fingers (excluding thumbs) of 5 fresh cadavers were used. Methylene blue dye was injected into the flexor tendon sheath using either a blind or sonographically guided injection technique (20 fingers for each technique). The location of the dye was then determined via dissection.

RESULTS: Dye was observed only in the tendon sheath (ie, optimal outcome) in 70% of sonographically guided injections and 15% of blind injections (P = .001). Dye was observed in the tendon proper (ie, unsafe outcome) in 30% of blind injections and 0% of sonographically guided injections (P = .02).

CONCLUSIONS: We found that sonographically guided tendon sheath injections were more accurate and may be potentially safer than blind injections. These findings suggest that sonographically guided injections should be considered over blind injections when treating trigger finger.