Effect of infraspinatus integrity on external rotation following reverse total shoulder arthroplasty for massive rotator cuff tears

Background The purpose of this study was to compare clinical outcomes between patients who underwent primary rTSA for mRCT involving anterosuperior (AS), posterosuperior (PS), and three-tendon (3T) tears. Method We identified patients who underwent primary rTSA for mRCT between 2011 and 2023 by two high-volume shoulder arthroplasty surgeons with minimum 1-year follow-up. Demographics and clinical outcomes were compared between groups preoperatively and 1-year postoperatively. Type of mRCT was assessed with MRI or CT arthrography and confirmed intraoperatively. Results Included were 224 shoulders (mean follow-up of 12.4 months). Patients with AS tears demonstrated significantly greater external rotation (ER, mean = 52.8°; P < 0.01) and internal rotation (IR, mean = 58.3°; P = 0.03) 1-year postoperatively than patients with PS and 3T tears. Patients with AS tears demonstrated greater mean improvements in ER than those with PS and 3T tears (21.3° vs. 7.8°, P = 0.04). Discussion There were no differences in patient-recorded outcome measures 1 year after rTSA for different mRCT subtypes. Patients with AS tears exhibited significantly higher ER and IR 1 year after rTSA than those with tears involving the infraspinatus tendon. These findings suggest patients with an intact infraspinatus tendon can expect greater improvement in and higher overall ER following rTSA. Level of Evidence III, Retrospective Cohort Study