Mismatched implants yield comparable outcomes in revision shoulder arthroplasty

Revision shoulder arthroplasty procedures pose unique challenges to shoulder surgeons. Efforts to mitigate bone loss, blood loss, operative time, and intraoperative complications may prompt the surgeon to consider retaining well-fixed components and combine them with components of a different manufacturer. This concept, known as mismatching, represents a viable solution to a dilemma encountered in the revision setting. The purpose of this study is to compare the clinical outcomes between patients treated with matched vs. mismatched implants in revision shoulder arthroplasty.

All revision shoulder arthroplasty cases performed by a single surgeon between 2012 and 2022 were reviewed. Using radiographs and operative reports, 44 patients were identified as mismatches, defined by humeral and glenoid components made by 2 different manufacturers. Demographic data, preoperative and postoperative range of motion, and patient-reported outcomes measures (American Shoulder and Elbow Surgeons, visual analog scale, Simple Shoulder Test, and stability) were collected. A larger cohort of all revision arthroplasties by the same surgeon (n = 574) was then used to perform a matched cohort analysis based on indication for revision. Rate of re-revision and patient-reported outcomes were then compared using simple statistics.

Twenty-five of the 44 total mismatches had a minimum of 1-year follow-up. Indications for revision included 13 failed reverse shoulder arthroplasty, 9 failed anatomic total shoulder arthroplasty, and 3 failed hemiarthroplasty. All were revised to reverse shoulder arthroplasty. In the matched cohort analysis (n = 25 mismatches and n = 281 matches), there were no differences in mean American Shoulder and Elbow Surgeons score, visual analog scale pain score, or Simple Shoulder Test at 1 year postoperatively. However, stability was significantly higher for mismatches (5.9) than for matches (3.5) on a 0-10 scale, with 10 being most stable (P = .039). There was an 11% (n = 5) re-revision rate among mismatches, compared with 13% among matches in the total revision cohort. Of the 44 total manufacturer-mismatched cases, 11 were also size-mismatched (differing glenosphere and socket size), and none of these required re-revision within the available short-term follow-up period.

Patients treated with mismatched components in this study demonstrated similar clinical outcomes and revision rates to those treated with matched components in revision shoulder arthroplasty. Although promising, these results are limited by a small sample size and short-term follow-up. A more definitive conclusion about the practice of mismatching implants will require further research with larger data sets and longer follow-up.