Total Shoulder Arthroplasty with a Metal-Backed, Bone-Ingrowth Glenoid Component

Background: Loosening of a cemented glenoid component is an important cause of failure in shoulder arthroplasty. This study was developed to examine the outcome of patients managed with a metal-backed, bone-ingrowth glenoid component as an alternative to a cemented component.

Methods: The study group included eighty-three total shoulder arthroplasties with a metal-backed, bone-ingrowth glenoid component performed between 1989 and 1994. Seventy-four shoulders had a diagnosis of primary osteoarthritis, and nine shoulders had other diagnoses. All patients were followed radiographically and clinically for a minimum of two years or until the time of revision surgery. Kaplan-Meier survival estimates were performed with revision and/or radiographic failure as the end points.

Results: The mean clinical follow-up was 9.5 years, and the mean radiographic follow-up was 7.1 years. Pain ratings (on a scale of 1 to 5) decreased from a mean of 4.7 preoperatively to 2.0 postoperatively. The mean range of motion in active elevation increased from 102° preoperatively to 135° postoperatively; the mean external rotation increased from 27° to 56°. Glenohumeral joint instability developed in fourteen shoulders. Radiographic changes consistent with glenoid component loosening were present in thirty-three shoulders. Polyethylene wear with metal wear of the glenoid component was noted in twenty-one shoulders, and humeral component loosening was seen in fifteen shoulders. Revision procedures were performed in twenty-six shoulders. There were no identifiable patient, disease, or surgical characteristics associated with failure, either clinically or radiographically. The five-year survival estimate free of revision or radiographic failure was 79.9% (95% confidence interval, 71.6% to 89.3%), and the ten-year survival estimate was 51.9% (95% confidence interval, 41.0% to 65.8%).

Conclusions: The high rate of failure of total shoulder arthroplasties performed with this metal-backed, bone-ingrowth glenoid component raises concerns as to its use, and perhaps the use of other types of metal-backed components, in shoulder arthroplasty, other than for special situations.

Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.