Baseplate retroversion does not affect postoperative outcomes after reverse shoulder arthroplasty

Abstract

Background: There is concern that excessive glenoid component retroversion leads to altered biomechanics and baseplate failure in reverse shoulder arthroplasty (RSA). However, much of this has been rooted in the total shoulder arthroplasty experience. In the current literature, it is not well defined whether glenoid baseplate positioning in reverse arthroplasty affects functional outcomes. Our practice has been to preserve glenoid bone stock without aiming for a certain degree of retroversion. We aimed to evaluate the correlation between pre- and postoperative retroversion in a cohort of RSAs and determine the effect of glenoid retroversion on functional outcomes, range of motion, and postoperative complications.

Methods: A retrospective review of patients who had an RSA between 2017 and 2019 was performed. Preoperative computed tomography scans were used to assess preoperative retroversion, and axillary radiographs were used for postoperative retroversion. Outcome measures included American Shoulder and Elbow Surgeons score, visual analog scale for pain score, Single Assessment Numeric Evaluation score, range of motion, radiographic lucency, and complications.

Results: A total of 271 patients were eligible for the study. There was a 76.9% 2-year follow-up rate. In total 161 patients had postoperative retroversion ≤15° (group A), and 110 patients had retroversion >15° (group B). There were no significant differences in American Shoulder and Elbow Surgeons, visual analog scale, or Single Assessment Numeric Evaluation scores. There were also no significant differences in postoperative range of motion. There was 1 baseplate failure in each group, and there was 1 patient in group B with asymptomatic radiographic loosening (baseplate at risk). The mean change in pre- to postoperative retroversion was 1° and 4° in groups A and B, respectively.

Conclusion: There was no significant difference in postoperative functional outcomes, range of motion, or complications between patients who had baseplate retroversion ≤15° vs. those who had retroversion >15°.

Keywords: Reverse total shoulder arthroplasty; clinical outcome; glenoid retroversion.