AANA Lab Course 906- Técnicas Avanzadas de Cirugía de Hombro-Fracturas de acromion y espina de la scapula tras protesis invertida-Philipp N. Streubel, MD

Fracturas de acromion y espina de la scapula tras protesis invertida-Philipp N. Streubel, MD

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This document, authored by Dr. Philipp N Streubel, addresses acromion fractures following reverse shoulder arthroplasty (RSA). These fractures represent the fifth most common complication post-RSA, with an incidence ranging from 1% to 10%, and a recent meta-analysis pinpointing approximately 4%. Most fractures occur within six months postoperatively and can arise due to stress fractures from increased deltoid loading or trauma (direct or indirect).<br /><br />Risk factors include osteoporosis, the presence of stress risers from superior screws (controversy exists here), and prosthesis design—with the Grammont design showing a 1.3% fracture incidence and the Aequalis Ascend onlay design a 4.3% rate.<br /><br />Diagnosis primarily uses plain radiographs, though these show low interobserver reliability and are useful mainly for displaced fractures. Computed tomography is the preferred modality, especially when radiographs are inconclusive or for assessing fracture healing.<br /><br />Two main fracture classification systems exist: Crosby and Levy. Crosby’s system classifies fractures by location—type I (anterior acromion near the coracoacromial ligament, often intraoperative avulsions, 36%), type II (just posterior to the acromioclavicular joint, 46%, potentially linked to acromioclavicular arthritis), and type III (posterior acromion or scapular spine, 18%, possibly related to screw stress risers). Levy’s classification focuses on post-op fractures—type I (anterior acromion), type II (middle acromion), and type III (acromion base), with type III fractures having the worst prognosis.<br /><br />Clinical outcomes post-fracture improve compared to pre-RSA status but remain inferior to patients without fractures. Symptomatic nonunions lead to poorer outcomes.<br /><br />Nonoperative management, mainly sling immobilization in abduction for six weeks, is appropriate for Crosby type I and nondisplaced fractures but results in about a 50% nonunion rate, though 75% have mild or no pain. Surgical treatment is indicated for displaced fractures and involves direct approaches with fixation via tension bands or plates and screws. Surgery is challenging due to deltoid tensile forces, poor bone stock, and a high failure potential. Evidence suggests surgery may offer better anterior flexion and less pain but similar consolidation time and functional scores compared to nonoperative care.<br /><br />In summary, acromion fractures post-RSA are uncommon but significantly impact clinical outcomes. Optimal management strategies remain unclear, requiring further research.

Keywords

acromion fractures

reverse shoulder arthroplasty

RSA complications

fracture incidence

risk factors

diagnosis methods

fracture classification

Crosby classification

Levy classification

treatment outcomes