Sonographic appearance of trigger fingers.

Objective: The purpose of this study was to describe the sonographic appearance of the first annular (A1) pulley-flexor tendon complex in patients with trigger fingers.

Methods: Thirty-three trigger fingers in 33 patients were examined with a 7- to 15-MHz probe. A control group consisted of 20 patients without trigger fingers. The study included systematic measurement of the thickness of the A1 pulley and a power Doppler assessment of the pulleys, tendons, and tendon sheaths.

Results: Thickening and hypoechogenicity of the A1 pulley were found in all patients with trigger fingers. Measurements of A1 pulley thickness were significantly different (P < .0001) between the groups without trigger fingers (mean, 0.5 mm; range, 0.4-0.6 mm) and with trigger fingers (mean, 1.8 mm; range, 1.1-2.9 mm). Hypervascularization of the A1 pulley on power Doppler imaging was found in 91% of the trigger fingers but was never found in the healthy control group. Flexor tendinosis was found in 48% of the trigger fingers; tenosynovitis was found in 55%; and both were found in 39%. In the control group, tenosynovitis and tendinosis were not found.

Conclusions: Thickening and hyper-vascularization of the A1 pulley are the hallmarks of trigger fingers on sonography. Other frequently observed features include distal flexor tendinosis and tenosynovitis.