Scapular dyskinesis refers to the abnormal mobility or function of the scapula ( Shoulder blade). The scapula fulfills many roles to facilitate optimal function of the shoulder.
Commonly, scapular winging is thought of being the result of muscle weakness or imbalance, as well as poor timing of muscular contraction. It can also develop from poor overhead mechanics and overuse or repetitive motions such as throwing or serving. While muscle weakness or imbalance may play a part in scapular winging, there are often underlying issues (neurological issues)
Normal function of the shoulder joint requires a scapula that can be properly aligned in multiple planes of motion of the upper extremity. Scapular dyskinesis is best considered an impairment of optimal shoulder function. As such, it may be the underlying cause or the accompanying result of many forms of shoulder pain and dysfunction. The scapula fulfills important functions in dynamic and static modes. In addition to upward rotation, the scapula is required to tilt posteriorly and externally rotate to clear the acromion from the moving arm in elevation and abduction.
In addition, the scapula must be able to internally/externally rotate in a synchronous manner to maintain the glenoid as a congruent socket for the arm in motion.
Shire AR, Stæhr TA, Overby JB, Bastholm Dahl M, Sandell Jacobsen J, Høyrup Christiansen D. BMC Musculoskeletal Disorders. 2017 Apr 17; 18: 158