The concept of a newly developed cup arthroplasty (Durom Cup) involves the replacement of the destroyed joint surface of the humeral head with minimal bone resection. In cases of additional massive cuff tear, the cup can be placed in a more valgic position to articulate with the glenoid and the acromion. The aim of this prospective study was to evaluate the results of this surface replacement as a hemiarthroplasty in rheumatoid arthritis.
Forty-five Durom Cups in 39 patients (30 women, 9 men) with rheumatoid arthritis were evaluated preoperatively and every 3 months postoperatively. Their average age was 62.7+/-12.3 years and the average follow-up 45.1+/-11.6 months with a minimum of 36 months. Concerning the cuff, 15 shoulders had an intact cuff (group A), 18 shoulders a partial tearing or a repaired rotator cuff (group B), and 12 shoulders a massive cuff tear (group C). The Constant Score was used, and the cups were examined radiologically.
In group A rheumatic shoulders, the Constant Score increased from 21.5+/-9.6 points preoperatively to 66.1+/-9.8 points at 36 months postoperatively; in shoulders of group B, from 19.6+/-9.7 points preoperatively to 64.9+/-9.6 points at 36 months postoperatively; and in shoulders of group C, from 17.5+/-8.7 points to 56.9+/-9.8 points at the latest follow-up examination. All shoulders were pain-free at the latest examination. No complications, component loosening or changes of cup position were observed.
The results of the Durom Cup are encouraging. In shoulders with additional massive cuff tear, the limited goal criteria were always achieved. Therefore, cup arthroplasty is a good alternative to other kinds of shoulder endoprostheses in rheumatic shoulders with and without massive cuff tear.