Summary Distal clavicle osteolysis is the painful development of bony erosions and resorption of the distal clavicle caused by repetitive trauma to the AC joint. Diagnosis is made with radiographs of the shoulder revealing osteolysis, cysts, erosions and resorption of the distal end of the clavicle. Treatment is a trial of NSAIDs, activity modifications, and corticosteroid injections. Arthroscopic versus open distal clavicle excision is indicated for patients with persistent symptoms that have failed nonoperative treatment. Epidemiology Demographics patients in their 20s, mostly male commonly seen in weightlifters Risk factors history of traumatic injuries Etiology Pathophysiology pathoanatomy caused by repetitive stress and micro-fracture in distal clavicle which leads to osteopenia Anatomy Osteology clavicle is S-shaped bone last bone to fuse Medial growth plate fuses early 20s Diarthrodial joint with fibrocartilage meniscus Ligamentous AC ligaments: horizontal stability CC ligaments: vertical stability Presentation Similar to AC joint arthritis Symptoms pain located at distal clavicle and anterior superior shoulder insidious in onset exacerbated by repetitive loading (ie. bench press or push-ups) Physical exam palpation tenderness at the distal end of clavicle and AC joint provocative test pain with cross-body adduction Imaging Radiographs recommended views AP clavicle Zanca view (15 degrees cephalad tilt) findings of the distal clavicle (should not involve the acromion) cysts osteopenia resorption and erosion tapering of distal clavicle AC joint widening Advanced Imaging MRI: increased signal of T2 sequences and bone marrow edema bone scan: increased uptake in the distal clavicle (may be seen earlier than radiographic changes) Treatment Nonoperative activity modification, NSAIDs indications login to view 1 more bullet modification login to view 2 more bullets corticosteroid injections indications login to view 1 more bullet technique login to view 1 more bullet Operative open or arthroscopic distal clavicle excision indications login to view 1 more bullet technique login to view 1 more bullet outcomes login to view 5 more bullets Techniques Arthroscopic distal clavicle resection (Mumford procedure) should resect only 0.5-1cm of the distal clavicle too large a resection can lead to AC joint instability Complications Horizontal instability avoid violating the posterosuperior capsule during distal clavicle excision as will lead to horizontal instability