Rheumatoid arthritis often leads to severe destruction of the glenohumeral joint, including synovitis and inflammation-induced alterations of the rotator cuff. Cup arthroplasty, or surface replacement of the shoulder, was introduced in the 1980s. The aim of this study was to evaluate the midterm results of the DUROM cup surface replacement for patients with rheumatoid arthritis affecting the glenohumeral joint.
From 1997 to 2000, forty-two DUROM cup hemiprostheses were implanted in a cohort of thirty-five patients (forty-two shoulders), who were evaluated preoperatively and again at three, twelve, and more than sixty months postoperatively. Six patients (seven shoulders) were lost to follow-up. Thirty-five shoulders in twenty-nine patients (twenty-one women and eight men with an average age of 61.4 years) could be evaluated prospectively after an average follow-up period of 73.1 months. Patients were evaluated clinically with the use of the Constant score, and a detailed radiographic analysis was performed to determine the presence of endoprosthetic loosening, glenohumeral subluxation, and glenoid bone loss.
The mean Constant score for the thirty-five shoulders increased from 20.8 points preoperatively to 64.3 points at a mean of 73.1 months postoperatively. There were three revisions: one to replace an implant that was too large, another to treat glenoid erosion, and a third due to loosening of the implant. No additional cases of loosening of the prosthesis or changes in cup position were observed radiographically. Over the five-year follow-up period, proximal migration of the cup increased in 63% of the shoulders, and the glenoid depth increased in 31%. With the numbers studied, no differences in clinical outcome were identified between patients with a massive rotator cuff tear and those with a smaller or no tear.
The midterm results of the cemented DUROM cup surface replacement for patients with advanced rheumatoid arthritis of the shoulder are very encouraging, even for patients with a massive tear of the rotator cuff. The advantage of this cup arthroplasty is the less complex bone-sparing surgery. In the event of failure of the implant, other reliable salvage options remain.