High delta angle after reverse total shoulder arthroplasty increases stresses of the acromion: biomechanical study of different implant positions.

Background: Acromial fractures after reverse total shoulder arthroplasty (RTSA) are a common complication. Nevertheless, only a few studies have identified risk factors for acromial fractures after RTSA. High delta angle (combination of inferiorization and medialization of the center of rotation [COR]) after RTSA was identified as a risk factor in recent studies.