Do individualized humeral retroversion and subscapularis repair affect the clinical outcomes of reverse total shoulder arthroplasty?

Background: This study aimed to evaluate the effects of an individualized angle of humeral retroversion and subscapularis repair on clinical outcomes after reverse total shoulder arthroplasty (RTSA) using a lateralized prosthesis. Methods: A retrospective analysis of 80 patients who underwent RTSA and had a minimum of 2 years' follow-up was performed. Individualization was based on the native retroversion angle, quantified from computed tomography images. Clinical outcomes (forward flexion, external rotation at the side, internal rotation at the back, functional scores, and pain) were compared between patients with individualized retroversion (group I, n = 52) and patients with a fixed retroversion angle of 20° (group II, n = 28). Group I was further subdivided into patients with a retroversion angle of 20° or less (subgroup A, n = 21) and patients with a retroversion angle greater than 20° (subgroup B, n = 31). We also compared outcomes in group I between patients with (n = 40) and without (n = 12) subscapularis repair. Results: Ranges of motion including external rotation and internal rotation, functional scores, and pain relief were significantly better in group I than in group II (P < .05 for all). No differences in clinical outcomes were found between subgroups A and B, although outcomes for both of these subgroups were better than those for group II (P < .05 for all). Subscapularis repair was not correlated with superior clinical outcomes. Conclusions: Individualized humeral retroversion may provide superior clinical outcomes to those of implantation of the humeral component at a fixed angle of 20° of retroversion. Repair of the subscapularis may not be essential for superior clinical outcomes in patients treated using a lateralized RTSA prosthesis.