Reverse shoulder arthroplasty (RSA) increases the moment arm of the deltoid, however there is limited knowledge on the accompanying changes in muscle architecture that play a role in muscle force production. The purpose of our study is to use a geometric shoulder model to evaluate the anterior deltoid, middle deltoid, and supraspinatus regarding 1) differences in moment arms and muscle-tendon lengths in small, medium, and large native shoulders, and 2) impact of three RSA designs on moment arms, muscle fiber lengths, and force-length (F-L) curves.
Source: JSES