Background: Patterns of scapular dyskinesis have unique scapular kinematics and associated muscular activation. The characteristics of scapular dyskinesis may be associated with functional disability. The investigators investigated whether the level of shoulder function and primary dysfunction items were different in each unique pattern of scapular dyskinesis. The factors associated with shoulder dysfunction in different patterns of scapular dyskinesis were identified.

Methods: Participants with unilateral shoulder pain were classified as having a single dyskinesis pattern (inferior angle prominence, pattern I; medial border prominence, pattern II) or a mixed dyskinesis pattern (patterns I+II). Clinical measurements with the Flexilevel Scale of Shoulder Function (FLEX-SF score), shoulder range of motion, anterior/posterior shoulder tightness, and pectoralis minor index were recorded. These clinical measurements, 3-D scapular kinematics (electromagnetic-based motion analysis), and associated muscular activation (electromyography on the upper, middle, and lower parts of the trapezius and serratus anterior muscles) during arm elevation were analyzed for associations with functional disability.

Inclusion Criteria:

• Subjects were from 18 to 50 years old and had unilateral shoulder pain around the shoulder complex, including the glenohumeral, scapulothoracic, sternoclavicular, and acromioclavicular regions, while performing shoulder movement.

Exclusion Criteria:

• Subjects were excluded if they had a history of shoulder dislocation, fracture, or shoulder surgery within the past 1 year, or a history of direct contact injury to the neck or upper extremities within the past 1 month. Subjects who had neurological disorders or demonstrated pain (VAS>3) during the overall testing procedures were also excluded.

Function-related factors in patients with scapular dyskinesis. Fifty-one participants (40 males; 11 females; mean age= 22.5±2.4 years; mean height=171.4 ± 8.0 cm; mean weight= 64.9 ± 10.5 kg) were recruited.