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Abstract

Background: Loosening of a cemented glenoid component is an important cause of failure in total shoulder arthroplasty. A metal-backed, bone in-growth glenoid component has been designed as an alternative. The purpose of this study is to examine the results of this type of total shoulder arthroplasty. Methods: One hundred and twenty-four total shoulder arthroplasties with metal-backed, bone in-growth glenoid components were performed between 1989 and 1994. All patients had a minimum radiographic and clinical follow-up of two years or until the time of revision surgery. Mean clinical follow up was 9.4 years; mean radiographic follow-up was 6.9 years. Degenerative joint disease was present in 71% of patients, rheumatoid arthritis in 14.5%, and other diagnoses in the remaining. The glenoid component was bone-grafted in 14 shoulders; rotator cuff tears were present in 24 shoulders. Results: Clinical data included pain ratings that decreased from an average of 4.5 preoperatively, to 2.0 postoperatively. Range of motion in active elevation increased from 102 degrees preoperatively, to 133 degrees postoperatively. Range of motion in external rotation increased from 30 degrees preoperatively, to 56 degrees postoperatively. All clinical data was significant (p=0.0001). Three major issues arose. Subluxation occurred in 38, radiographic change was present in 62 shoulders (glenoid loosening in 47 (35%), humeral loosening in 20 (15%), polyethylene wear with metal wear of the glenoid component in 28 (21%)). Revision procedures were required in 40 shoulders (27%). There were no identifiable patient, disease, or surgical characteristics associated with failure, either clinically or radiographically. Kaplan-Meier survival estimates were performed for the endpoint of revision and/or radiographic failure. The one year survival estimate was 93.5% (standard error 0.022). The five year survival estimate was 79.8% (standard error 0.037). The ten-year survival estimate was 48.2% (standard error 0.052). Conclusions: A higher rate of failure of total shoulder arthroplasties performed with a metal-backed, bone in-growth glenoid component raises concern for its use in shoulder arthroplasty, other than for special situations. If noted, the author indicates something of value received. The codes are identified as follows: a, research or institutional support; b, miscellaneous funding; c, royalties; d, stock options; e, consultant or employee. *The Food and Drug Administration has not cleared the drug and/or medical device for the use described in this presentation (ie, the drug or medical device is being discussed for an “off-label” use). If noted, the author indicates something of value received. The codes are identified as follows: a, research or institutional support; b, miscellaneous funding; c, royalties; d, stock options; e, consultant or employee. *The Food and Drug Administration has not cleared the drug and/or medical device for the use described in this presentation (ie, the drug or medical device is being discussed for an “off-label” use).