The metal-backed glenoid component in rheumatoid disease: eight- to fourteen-year follow-up.

HYPOTHESIS

We believe the variable reported survivorship of the metal-backed glenoid is related to the design of the component. This study reports the outcome and survivorship of the uncemented glenoid in rheumatoid patients with an intact or repairable rotator cuff at surgery, and considers the key design features that may predict longevity of this component.

METHOD

Forty-six shoulders in 39 patients (31 women), with a mean age of 55 years (range, 35-86 years) received a total shoulder replacement with a screw-fixed porous coated metal-back glenoid. Twenty-nine patients (36 shoulders) were monitored for a mean of 132 months (96-168 months), and 10 were lost to follow-up or died before 8 years of follow-up. A Constant score was measured preoperatively and annually from the time of surgery. Radiographs were assessed for lucency, loosening, and superior subluxation of the humeral head.

RESULTS

The Constant score improved from a mean of 20.6 preoperatively to 33.5 at last follow-up (P < .001). Implant survivorship at 10 years was 89%. Five were revised: 3 for pain with associated superior subluxation, 1 for infection, and 1 for aseptic loosening. In the 4 patients with lucent zones around the glenoid, superior subluxation of the humeral head had occurred 2 to 4 years before the observed lucent lines.

DISCUSSION

The uncemented glenoid performs well in the rheumatoid shoulder, giving pain relief and improved functional outcome. The survivorship is comparable to previously reported studies.

CONCLUSION

We believe the key design features in the survivorship of the metal-backed glenoid are: a low-profile tray, with a fully coated bone ingrowth substance at the plate-bone interface, a conical stem, and secure screw fixation.