The influence of preoperative rotator cuff cross-sectional area and strength on postoperative outcomes in reverse shoulder arthroplasty.

Abstract

Although preoperative function and range of motion (ROM) are determinants of postoperative outcome following reverse shoulder arthroplasty (RSA), there is limited data on the influence of preoperative rotator cuff status. The purpose of this study was to evaluate the relationship between preoperative rotator cuff physiologic cross-sectional area (PCSA) and strength on postoperative RSA outcome. A retrospective review was conducted on 53 primary RSAs from a multicenter database performed between 2015 and 2019 using a 135° humeral neck-shaft angle. Preoperative magnetic resonance imaging and computed tomographic scans were used to assess the PCSA of the subscapularis, supraspinatus, infraspinatus, and teres minor. American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) scores, ROM, and strength were measured preoperatively and at a minimum of 2 years postoperatively. Correlation coefficients were used to determine the relationship between variables. There were no significant correlations between preoperative PCSA of any rotator cuff muscles and postoperative ASES scores. Preoperative subscapularis PCSA positively correlated with change in belly press (BP) strength following RSA (⍴ = 0.37, P = .006). Preoperative abduction strength was significantly correlated with postoperative abduction strength (⍴ = 0.297, P = .006). Preoperative external rotation (ER) strength was significantly correlated with postoperative ER (⍴ = 0.378, P = .005) and abduction (⍴ = 0.304; P = .032) strength. Preoperative BP strength negatively correlated with postoperative ASES (⍴ = -0.283, P = .042) but positively correlated with postoperative BP (⍴ = 0.411, P = .001) and abduction (⍴ = 0.367, P = .009) strength. With the use of a 135° humeral implant, there is limited correlation between preoperative PCSA and postoperative outcomes 2 years following RSA; the only significant correlation was between preoperative subscapularis PCSA and postoperative BP strength. Preoperative strength is positively correlated with postoperative strength but not ROM or ASES scores.