Isokinetic shoulder strength correlates with level of sports participation and functional activity after reverse total shoulder arthroplasty

Abstract

Reverse total shoulder arthroplasty (RTSA) is increasingly being performed. Many patients may wish to return to high levels of sporting activity. This study aimed to evaluate the correlation of isokinetic shoulder strength with level of participation in sport and recreation after RTSA. We surveyed 51 patients at a mean of 29.5 months (range, 12-60 months) after surgery. Mean age was 74.1 years. Patient-reported sporting activity was classified as low, medium, or high demand. All patients completed the shortened Disabilities of the Arm, Shoulder, and Hand questionnaire and the Oxford Shoulder Score and underwent Biodex dynamometer testing of the RTSA evaluating isokinetic shoulder strength in flexion and extension, abduction and adduction, and internal and external rotation. Reported sporting activity was high demand in 35% and moderate demand in 43%. There was a large variation in shoulder isokinetic strength parameters especially for internal and external rotation. With the exception of abduction, a significant correlation was noted between strength and the level of sports participation that patients reported (P < .03). A significant correlation was also noted between strength and patient-reported outcome measures for internal rotation and arm flexion and abduction (P < .05). Most patients reported returning to moderate- or high-level sporting activity in the short term after RTSA. Isokinetic shoulder strength, especially in internal rotation and arm flexion, positively correlates with both patient-reported level of participation in sports and recreation and daily function.