Effect of subscapularis repair in patients with an intact rotator cuff undergoing reverse total shoulder arthroplasty

Abstract

BackgroundReverse total shoulder arthroplasty (rTSA) is increasing in popularity worldwide. There remains considerable debate as to whether to repair subscapularis or not following the procedure. Previous research into all indications demonstrates similar outcomes regardless of subscapularis (SSC) repair when using a medial glenoid/lateral humeral implant. The purpose of this study is to assess the effects of SSC repair on postoperative shoulder function and patient reported outcomes scores only in patients with an intact rotator cuff undergoing rTSA. MethodsPatients who underwent a primary rTSA for osteoarthritis with a minimum of 2 years follow-up were identified from an international shoulder registry. Patients with rotator cuff tears, cuff arthropathy, or post-traumatic arthritis were excluded. They were then divided into age and gender matched groups based on whether they had SSC repaired or not; 436 patients were analyzed in total, with 218 in each group. Numerous outcome measures between groups were compared, including active shoulder range of motion, complication rates, and 7 different patient reported shoulder outcome scores, using MCID (Minimal Clinically Important Differences), SCB (Substantial clinical benefit), and a 2 tailed paired T-Test. ResultsIn both groups, improvement in average shoulder movement and patient reported shoulder scores exceeded the threshold of SCB with 93% reporting their symptoms were better or much better in both groups. Those who had SSC repaired demonstrated a statistically significantly better mean active forward flexion (144° vs. 138°, P= .021) and mean internal rotation score (4.8 vs. 4.0, P= <.05), however these differences did not exceed the MCID where available. With regard to patient reported scores, those who had SSC repaired demonstrated a statistically significantly better mean Constant score (71 vs. 68, P= .05) and Shoulder Arthroplasty Smart Score (78 vs. 75, P= <.05), however these differences did not exceed the MCID for either score (5.3 and 6.1 respectively). There was no difference in complication rates between groups, including dislocation. ConclusionThis study demonstrates excellent results following rTSA with a medial glenoid/lateral humeral implant design regardless of whether the SSC was repaired or not. For the majority of patient reported scores and shoulder movements there was no significant difference between SSC repaired and nonrepaired groups, and where statistically significant differences were noted, the difference did not exceed the MCID in any measure. Level of EvidenceLevel III; Retrospective Comparative Study