Background: Shoulder arthroplasty with a stemmed prosthesis is a
recognized treatment for rheumatoid arthritis of the shoulder. The humeral
component of the Copeland cementless surface replacement arthroplasty consists
of a cup for surface replacement with a short central peg for primary fixation
to the bone. We hypothesized that surface replacement may offer some
advantages over stemmed prostheses.
Methods: Between 1986 and 1998, seventy-five shoulders underwent
surface replacement arthroplasty (thirty-three hemiarthroplasties and
forty-two total shoulder arthroplasties) for the treatment of rheumatoid
arthritis. The results of these procedures were reviewed after an average
duration of follow-up of 6.5 years. Patients were assessed with use of the
Constant score, a patient satisfaction score, and radiographs.
Results: The average Constant score was 47.9 points (age and
sex-adjusted score, 71%) in the hemiarthroplasty group and 53.4 points (age
and sex-adjusted score, 76%) in the total shoulder replacement group. The mean
range of active flexion improved from 50° in the hemiarthroplasty group
and 47° in the total shoulder replacement group to 101° and 104°,
respectively. Seventy-two of the seventy-five shoulders were considered by the
patients to be much better or better at the time of the review. Of the
sixty-eight humeral implants that were evaluated radiographically, fifty-six
(82%) showed no lucencies, eleven (16%) showed localized lucencies of <1 mm
in width, and one was definitely loose. Of the thirty-nine glenoid implants
that were evaluated radiographically, nineteen (49%) showed no lucencies,
nineteen showed localized lucencies of <1 mm, and one was definitely loose.
No lucencies were observed adjacent to the hydroxyapatite-coated implants.
Thirty-nine (57%) of the sixty-eight shoulders showed some degree of superior
subluxation. Three patients required a major reoperation: two required a
revision because of loosening of both components, and one patient with pain at
the site of a hemiarthroplasty had a revision to a total shoulder arthroplasty
to provide relief.
Conclusions: The indications for this surface replacement are the
same as those for the conventional stemmed prostheses, but the surface
replacement has the advantage of bone preservation as well as avoidance of the
potential complications associated with a long humeral stem in rheumatoid
bone. This procedure is not suitable for severely damaged joints in which the
humeral head is insufficient or too soft.
Level of Evidence: Therapeutic study, Level IV (case
series [no, or historical, control group]). See Instructions to Authors for a
complete description of levels of evidence.