Deltoid Muscle Injury

Deltoid muscle ruptures are uncommon injuries, generally occurring secondary to massive rotator cuff tears (due to proximal migration of the humeral head, leading to compression of the undersurface of the deltoid by the greater tuberosity), repeated corticosteroid injections within the muscle or subacromial space, acute trauma or after open rotator cuff repair. The diagnosis is usually made clinically with deformity in the contour of the deltoid, a subcutaneous bruise and upper arm swelling. Common imaging modalities are; plain radiographs, to evaluate proximal humeral head migration in case of rotator cuff tear arthropathy; Ultrasound showing a gap within the muscle fibers; and above all magnetic resonance imaging (MRI), evaluating both potential deltoid muscle tears and associated rotator cuff pathology. Treatment is either nonoperative (nonsteroidal anti-inflammatory drugs, rest, and physical therapy) especially in elderly patients with chronic injuries or operative with early surgical repair indicated for complete rupture in young patients.