Bipolar implant shoulder arthroplasty.

A bipolar implant was designed by the author in 1975 for reconstruction of the severely arthritic shoulder. It has the advantage of not requiring glenoidal component fixation, but still provides an artificial joint interface. The ball of the humeral intramedullary stemmed component articulates with a polyethylene bearing within the glenoid cup component. This bipolar prosthesis was implanted in 15 shoulders of patients who presented severe arthritic shoulder disabilities. The follow up period averaged 41 months. Nine patients had rheumatoid arthritis, and five had osteoarthritis; all presented with severe pain and joint crepitation with loss of motion. A "shoulder score" system, based on the rating of pain, activities of daily living and range of motion, was devised to categorize the results obtained. Patients obtained greatly improved range of motion with good to excellent pain relief and very good functional restoration. Radiographically, the implant was well tolerated and there was no stem loosening. This procedure appears to be safe and efficacious for use in the severely arthritic shoulder.