GLENOID REPLACEMENT IN TOTAL SHOULDER ARTHROPLASTY

Since its first descriptions, total shoulder arthroplasty was aimed at improving pain and function in patients with severe disabling arthritis of the shoulder joint. Total shoulder arthroplasty has been a well-recognized and successful treatment for many pathologic processes affecting the glenohumeral joint; however, replacement of the glenoid has been, and continues to be, a controversial issue. The decision to replace the glenoid is influenced by the specific pathologic changes of the soft tissue anatomy and the presence or lack of sufficient glenoid bone stock for fixation of the glenoid component. The distinct anatomic and biomechanical characteristics of the glenoid have necessitated specific glenoid component design and fixation considerations. Adequate surgical exposure is critical for appropriate glenoid replacement, and is dependent on meticulous surgical techniques and the use of appropriate retractors and instrumentation that allow for safe access to the glenoid surface. The pathologic indications for total shoulder arthroplasty have been shown to correlate with outcome. Patients with osteoarthritis and avascular necrosis generally have better functional results than those with rheumatoid arthritis because of better soft tissue quality and glenoid bone stock. 6,11,12,23 Over the last 20 years, several authors have reported good results with total shoulder arthroplasty. Nevertheless, glenoid component-related problems have been widely described in the literature. 8,9,15,16,18,44 As in other types of joint resurfacing, glenoid component loosening has been a major concern in total shoulder arthroplasty. However, direct correlation between radiographic signs of loosening of the glenoid and symptomatic clinical loosening has not yet been established. The incidence of radiolucent areas surrounding the glenoid has been reported to be between 22% and 95%. 1,3,8,9,21 Incidence rates of clinical loosening or failure in short-to medium-term studies have been reported to be significantly lower. Torchia and Cofield, however, recently reported a long-term incidence of 44% of patients developing clinical loosening after presenting with lucency. 40 In summary, the outcome of total shoulder arthroplasty is largely based on the quality of glenoid component fixation, which, in turn, is related to the amount and quality of bone stock, glenohumeral stability, and rotator cuff function. This article discusses the anatomic and pathologic indications for glenoid replacement, surgical techniques, and results.