Electromyographic and kinematic study of reverse total shoulder arthroplasty: an observational prospective cohort study.

Background: Reverse total shoulder arthroplasty (RTSA) procedures have significantly increased in the last decade as an alternative to the current treatments for cuff-tear arthropathy. Since Grammont's theory in 1987, few data about the in vivo kinetics of the shoulder-girdle musculature in patients with RTSA have been available. The goals of this study are to (1) describe the contribution of principal muscles around the shoulder by electromyography and (2) access the range of motion of 5 movements of patients with RTSA compared with normal shoulders.