Axial rotation moment arms of the shoulder musculature after reverse total shoulder arthroplasty

Abstract

Background: Reverse total shoulder arthroplasty changes the lines of action of the shoulder muscles, resulting in increases in the moment arms of the major abductors and flexors of the glenohumeral joint; however, at present little is known about the axial rotation capacity of the musculature after this procedure. The purpose of this study was to measure the instantaneous axial rotation moment arms of all of the major muscles spanning the glenohumeral joint during abduction and flexion after reverse total shoulder arthroplasty. Methods: Reverse total shoulder arthroplasty was performed on eight entire cadaveric upper extremities. Specimens were mounted onto a testing apparatus, and the inter..