Deltoid Rupture / Avulsion

This is a deltoid insufficiency from iatrogenic deltoid rupture or avulsion, which is the commonest cause of this injury. The anterior deltoid takes origin from the anterior acromion, so during open or arthroscopic acromioplasty - or open rotator-cuff surgery - it can be detached or devitalised, and the resulting deltoid failure is disabling because the deltoid is the prime mover of the shoulder. The patient presents as this one has: weakness of abduction and elevation, pain, a visible or palpable contour defect over the deltoid, and, if there is associated cuff deficiency, anterosuperior escape of the humeral head. I would confirm it on examination, correlating with the operative history, and image it with ultrasound and especially MRI to define the deltoid defect, its retraction and any associated cuff pathology. Treatment is difficult: for symptomatic insufficiency I would consider surgical repair - direct reattachment of the deltoid to the acromion using transosseous sutures or suture anchors, or for larger or chronic defects a local flap or allograft reconstruction - but I would counsel the patient that results are variable and there is no firmly established standard technique. The most important lesson, though, is prevention: the deltoid origin must be protected during shoulder surgery and any split securely repaired to bone, and a postoperative deltoid detachment should be recognised and repaired early, before retraction and atrophy make reconstruction even harder.