The Shoulder at Risk: Scapular Dyskinesis and Altered Glenohumeral Rotation

Abstract

The shoulder at risk is a concept that describes alterations in the kinetic chain (the sequential coordinated and task-specific development of force) and shoulder that produce an impairment of optimum function. The glenohumeral (GH) structures may be susceptible to injury when exposed to the inherent high demands of throwing, creating the disabled throwing shoulder. Although multiple factors can lead to a shoulder at risk, the 2 most common factors are scapular dyskinesis and alterations in GH motion. Dyskinesis represents an alteration of static scapular position or dynamic scapular motion in coordination with arm motion and is best considered an impairment of optimum shoulder function, with potential harmful effects on the anatomical structures. Altered GH rotation creates a shoulder at risk by decreasing the rotation and increasing the amount of translation. Both impairments are capable of altering shoulder motions and loads and should be considered contributors to the shoulder at risk of injury. A focalized physical examination should be utilized to not only initially assess for the presence or absence of these impairments but also periodically assess throughout training or competition as both impairments can develop overtime even in the absence of injury.