Evaluation of a nonconstrained total shoulder prosthesis.

We reviewed the radiographs and medical records of 76 patients with 98 nonconstrained total shoulder prostheses: 68 were inserted for rheumatoid arthritis, 25 for osteoarthritis, and five for avascular necrosis. The radiographic follow-up averaged 36 months. Radiographic evidence of postoperative complications was noted in 37 (38%) of 98 shoulders: dislocation of the humeral head (six), upward migration of the humerus (24), loosening of the glenoid compartment (15), loosening of the humeral component (five), subsidence of the humeral component (seven), and heterotopic bone formation (six). Patients with a dislocated prosthesis had limitation of motion, poor function, and residual pain. No increase in pain was associated with proximal subluxation of the humerus. No correlations were found between any of the radiographic findings (the presence of radiolucent lines about the glenoid or humeral components, humeral subsidence, or ectopic ossification) and any of the clinical findings (pain relief, range of motion, motor power, or functional improvement).