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).