Abstract
Shoulder impingement syndrome is highly prevalent among overhead athletes, with rehabilitation typically requiring three to six months before returning to the sport. A 20-year-old male collegiate baseball outfielder (right-hand pitcher, left-hand batter) developed right-shoulder pain during throwing and was diagnosed with internal impingement two months after onset. Pain occurred in the early cocking phase, with 0° internal rotation at 90° flexion and abduction limited to 140°. Pain was induced by 90° abduction [numeric rating scale (NRS): 8/10]. The strength of the infraspinatus and teres minor was reduced, and the Neer, Hawkins, and Hornblower tests were positive. Dynamic ultrasonography revealed impaired teres minor contractions with compensatory posterior deltoid activation. Treatment included manual range-of-motion and flexibility exercises, ultrasound-guided real-time visual biofeedback once weekly to facilitate selective teres minor activation, and a structured at-home program emphasizing daily repetitions of teres minor contractions. Active external rotation in the elevated arm position improved after two weeks, and teres minor strength increased, allowing the initiation of a return-to-throw program. At four weeks, the NRS score decreased from 8/10 to 3/10, and the patient was able to throw 20 m. He achieved his pre-injury performance level at six weeks following five therapy sessions, and returned to competition before the league season. At the three-month follow-up, the patient remained asymptomatic and continued to play without any recurrence. Ultrasound-guided real-time visual biofeedback accelerated the player's return to the sport despite shoulder impingement symptoms. Our approach can serve as a valuable adjunct to conventional rehabilitation, potentially reducing loss of time in overhead athletes.