Morphological alterations of the tendon and pulley on ultrasound after intrasynovial injection of betamethasone for trigger digit

PURPOSE The aim of this study was to elucidate whether intrasynovial corticosteroid injections for trigger digit reduced the volume of the tendon and pulley on high-resolution ultrasonography. METHODS Twenty-three digits of 20 patients with trigger digit were included. Each affected finger was graded clinically according to the following classification: grade I for pre-triggering, grade II for active triggering, grade III for passive triggering, and grade IV for presence of contracture. Axial ultrasound examinations were performed before an intrasynovial corticosteroid injection and at an average of 31 days after the injection. The transverse diameter, thickness, and cross-sectional area of the tendon and the thickness of the pulley were measured by two independent, blinded researchers. RESULTS At least 1 grade of improvement was achieved in this study group by the time of the second examination. The transverse diameter and cross-sectional area of the tendon and the thickness of the pulley significantly decreased (P<0.05). CONCLUSION The injection of a single dose of betamethasone improved clinical symptoms by reducing the volume of both the tendon and pulley, which may be related to the fact that tendon and pulley ruptures are delayed by corticosteroid injections.