Exactech Equinoxe anatomic vs. reverse total shoulder arthroplasty for primary osteoarthritis with an intact rotator cuff in patients with no glenoid deformity

Abstract

Background

Studies comparing anatomic and reverse total shoulder arthroplasty (aTSA, rTSA) for rotator cuff-intact glenohumeral osteoarthritis (RCI-GHOA) frequently fail to control for selection bias secondary to glenoid bone loss. Comparisons of similar patient populations without glenoid deformity may better evaluate potential differences in outcomes. The purpose of this study is to compare the outcomes of a matched cohort of aTSA and rTSA patients with RCI-GHOA and no glenoid bone loss.

Methods

A retrospective review of primary aTSA/rTSA for RCI-GHOA with an A1 or B1 glenoid between 2007 and 2020 was performed. Matched cohorts were conceived based on age, sex, follow-up, Walch class, prior surgery, preoperative shoulder arthroplasty smart (SAS) score, preoperative forward elevation, and preoperative abduction. Range of motion, outcome scores, and rates of complications and reoperations were compared.

Results

A total of 310 matched shoulders (155 aTSA, 155 rTSA) were evaluated at a mean 3.2 years follow-up. Postoperatively, aTSAs had more favorable abduction (146 ± 27° vs. 133 ± 26°, P < .001), internal rotation score (4.6 ± 1.3 vs. 4.1 ± 1.3, P = .004), external rotation (53 ± 15° vs. 43 ± 14°, P < .001), Constant score (73.6 ± 10.5 vs. 70.5 ± 12.8, P = .039), and SAS score (81.1 ± 9.7 vs. 77.2 ± 10.2, P = .002). However, when assessing improvement from preoperative state, only abduction remained significantly greater in the aTSA cohort (60° vs. 47°, P = .024). Patients undergoing aTSA achieved substantial clinical benefit at a higher rate for abduction (78% vs. 64%, P = .034) and external rotation (61% vs. 45%, P = .034). There was no difference in the incidence of complications (3.9% vs. 1.9%, P = .501) or revision surgery (3.2% vs. 0.6%, P = .214).

Conclusion

In patients with RCI-GHOA with no bone loss, treatment with rTSA demonstrated similar improvements compared to a matched aTSA cohort except for less improvement in abduction. rTSA does not appear to offer functional benefits over aTSA in this population. Longer term follow-up of this cohort needs to be considered to assess the longitudinal functional and revision rates of these patients.