Scapular Fractures After Reverse Shoulder Arthroplasty

Abstract

With the increased use of reverse shoulder arthroplasty, the complication of postoperative scapular fracture is increasingly recognized. The incidence is variable and dependent on a combination of factors including patient age, sex, bone mineral density, diagnosis of inflammatory arthritis, acromial thickness, and implant-related factors. Acromial stress reactions are a clinical diagnosis based on a history and physical examination. These are treated successfully with 4 to 6 weeks of immobilization. Acromial stress fractures are visible on imaging studies and are classified based on anatomic location by the classification systems of Crosby and Levy. In approximately 20% of fractures, a CT scan is necessary to make the diagnosis. Treatment is typically nonsurgical that leads to a high rate of nonunion or symptomatic malunion. Scapular spine fractures (type III) can be treated with either nonsurgical or surgical management; however, obtaining fracture union is challenging, and the outcomes are typically inferior to that of type I and II fractures. Although the nonsurgical and surgical treatment of acromial stress fractures improves the clinical outcomes from the patient's preoperative state, the outcomes of a control group undergoing reverse shoulder arthroplasty without fracture are better. The exception to this is oftentimes the displaced and angulated type III fracture.T he number of shoulder arthroplasty procedures performed is rapidly growing, mostly because of the development of the reverse shoulder arthroplasty (RSA). 1 Since its approval in the United States in 2003, the indications for RSA are expanding. Numerous studies have documented the effectiveness of RSA in relieving pain and restoring function in patients with rotator cuff tear arthropathy, massive irreparable rotator cuff tears, complex proximal humerus fractures, fracture malunions, and severe glenohumeral arthritis with glenoid deformity and in revision arthroplasty. [2][3][4][5] Common complications after RSA include scapular notching, hematoma, instability, infection, and acromial or scapular spine fracture. [6][7][8][9][10] Postoperative acromial fracture is unique to RSA secondary to the altered shoulder biomechanics with distalization and medialization of the center of rotation. 2 This places more tension on the deltoid muscle origin of the clavicle, acromion, and scapular spine, and it leads to