Radiographic restoration of native anatomy: a comparison between stemmed and stemless shoulder arthroplasty

Background: Shoulder arthroplasty is a reliable procedure for patients with degenerative glenohumeral disease, and reproduction of native shoulder anatomy leads to superior outcomes. The aim of this study was to compare the ability of stemmed and stemless implants to radiographically restore native glenohumeral anatomy. Methods: Shoulder arthroplasties were performed in 79 patients, with 58 receiving a stemless implant and 21 receiving a stemmed implant. Preoperative and postoperative radiographs were assessed for humeral head height, humeral head centering, humeral head medial offset, humeral head diameter, humeral neck angle, and lateral humeral offset by 2 independent viewers. Measurements were scored and summed to identify the anatomic reconstruction index (ARI). Radiographic measurements were compared using the Student t test, and significance was set at P < .05 for all statistical analyses. Interobserver agreement of radiographic analyses was assessed using the intraclass correlation coefficient, finding excellent reliability (intraclass correlation coefficient, 0.92). Results: Five of six radiographic measurements along with the calculated ARI demonstrated no differences between stemmed and stemless shoulder implants (humeral head diameter, P = .651; humeral head height, P = .813; humeral head medial offset, P = .592; lateral humeral offset, P = .311; humeral head centering, P = .414; and ARI, P = .862). Stemless implants showed improved restoration of the native humeral neck angle (0° for stemless vs. −3° for stemmed, P = .017). Conclusion: Radiographic restoration of anatomy is similar for stemmed and stemless shoulder arthroplasty implants.