Ultrasound-Guided Exercise Therapy Targeting the Supinator and Its Radial Nerve Branch for Refractory Lateral Elbow Pain: A Case Series

Lateral epicondylitis is commonly attributed to tendinopathy of the extensor carpi radialis brevis (ECRB). Although eccentric exercises, prolotherapy, and percutaneous ultrasonic tenotomy (PUT) are frequently used, a subset of patients experience persistent pain. The potential contributions of the supinator muscle and its radial nerve branch to rehabilitation have not been adequately explored. We report three patients (two females and one male; aged 20-59 years) with refractory lateral epicondylitis and residual pain after injection or PUT. All the patients exhibited severe pain during the modified Thomsen test in supination ("reverse Thomsen test"). Ultrasonography revealed impaired supinator activation with deep tenderness. Each patient underwent ultrasound-guided visual feedback training to selectively activate the supinator muscle, combined with a structured home exercise program. After 12-18 weeks of therapy (three to six sessions), pain resolved, tenderness subsided, and Disabilities of the Arm, Shoulder and Hand (DASH) scores improved significantly (Case 1: 25→9; Case 2: 48→4; Case 3: 15→4). These cases suggest that supinator dysfunction and involvement of the radial nerve branch may contribute to persistent lateral elbow pain. The reverse Thomsen test reliably reproduced the symptoms consistent with nerve stretching at the supinator level. Ultrasound-guided exercises facilitated selective supinator recruitment, reduced compensatory extensor overactivity, and improved functional outcomes. These findings indicate that supinator-focused rehabilitation may be a valuable therapeutic option in refractory cases. Ultrasound-guided exercise therapy targeting the supinator and its radial nerve branches provided substantial clinical benefits to patients with refractory lateral epicondylitis. A positive reverse Thomsen test result may serve as a clinical indicator of supinator involvement and help guide treatment selection.