Muscle and Joint Function After Anatomic and Reverse Total Shoulder Arthroplasty Using a Modular Shoulder Prosthesis

Abstract

Changes in joint architecture and muscle loading resulting from total shoulder arthroplasty (TSA) and reverse total shoulder arthroplasty (RSA) are known to influence joint stability and prosthesis survivorship. This study aimed to measure changes in muscle moment arms, muscle lines of action, as well as muscle and joint loading following TSA and RSA using a metal‐backed uncemented modular shoulder prosthesis. Eight cadaveric upper extremities were assessed using a customized testing rig. Abduction, flexion, and axial rotation muscle moment arms were quantified using the tendon‐excursion method, and muscle line‐of‐force directions evaluated radiographically pre‐operatively, and after TSA and..