Case Report:
An active 37-year-old, right-hand dominant male presented to the clinic for left shoulder pain and weakness that began seven days prior while lifting weights. His symptoms started abruptly after completion of a set of barbell shoulder shrugs with 450 pounds. During the action he felt a popping sensation over the left posterior shoulder, followed by sharp pain. There was associated deformity and swelling following the injury. He was employed as a heavy laborer and felt his work was limited by these new symptoms. He denied any previous shoulder trauma, injury, or prior shoulder girdle corticosteroid injections. On physical exam there was evident point tenderness over the insertion site of posterior deltoid fibers on the humerus as well as in the main deltoid muscle belly. During strength testing of the left shoulder abduction the posterior deltoid was graded 4/5.
Radiographs of the patient’s shoulder showed no fracture, subluxation, dislocation, abnormal calcifications or narrowing of the acromiohumeral interval. MRI revealed tendon avulsion of the posterior head of the deltoid muscle from the deltoid tuberosity of the humerus (Figure 1).