Unconstrained shoulder arthroplasty.

OBJECTIVE: To evaluate the results of 36 unconstrained shoulder arthroplasties. METHODS: In the series, 24 total and 12 hemi-arthroplasties of the shoulders were performed with unconstrained shoulder prostheses in 29 patients who suffered from glenohumeral degenerative arthritis, rheumatoid arthritis, avascular necrosis and proximal fracture of humerus, respectively. Follow-up averaged 6.2 years. All patients were evaluated pre- and post-operatively using the rating system of the Society of American Shoulder and Elbow Surgeons which assesses the severity of pain, strength of muscles around shoulder, stability, range of motion and functional activities of daily living. Radiolucent line and migration of prostheses were observed postoperatively on X-rays. RESULTS: Postoperatively, the rate of pain relief was 91.3%, and active range of motion increased by 47 in forward flexion, 43 in abduction, 30 in external rotation, and 4 segments in internal rotation. Preoperatively the average points of 6 functional activities patients could perform was 0.8, and postoperatively 3.1. On postoperative X-ray, proximal migration of the humerus was seen in 8 shoulders, 6 of which had either a torn or absent rotator cuff. Radiolucent lines were seen around 1 humeral component and 9 glenoid components. One humeral and 2 glenoid components loosened. CONCLUSIONS: These results suggest that unconstrained shoulder arthroplasty is a satisfactory and safe technique.