MODULAR TOTAL SHOULDER REPLACEMENT - DESIGN RATIONALE, INDICATIONS, AND RESULTS

Modular total shoulder systems offer many advantages over nonmodular d esigns. Modularity facilitates precise placement of the humeral head w ith respect to the rotator cuff and tuberosities, allows for soft tiss ue tensioning and balance with variable neck lengths, and simplifies r evision surgery by allowing removal of the humeral head while maintain ing a well-fixed humeral stem. This review includes 47 total shoulder arthroplasties performed in 40 patients from 1986 to 1991. The average patient age was 62.3 years, with followup averaging 54 months. Sevent een patients had rheumatoid arthritis, and 22 had osteoarthritis. In t he remaining 8 patients, 5 had posttraumatic arthritis, 2 had avascula r necrosis, and 1 had cuff tear arthropathy. Glenoid revision was requ ired in 3 patients, and symptomatic loosening occurred in only 1. Pain relief was achieved in 93.5% of patients. Range of motion improved 34 .9 degrees in forward flexion, 18.1 degrees in external rotation, and 4 vertebral levels of internal rotation. Lucent lines were evaluated o n the anteroposterior (AP) and axillary radiographs. On the AP radiogr aph, 16 shoulders demonstrated lucency about the glenoid component. Pr ogression beyond 2 mm occurred in 5 shoulders, and symptoms requiring revision developed in one patient. Twenty-two patients demonstrated a lucency on the axillary radiograph, and 9 patients progressed beyond 2 mm. None required revision. The authors present the results and discu ss surgical and design considerations of modular total shoulder arthro plasty.