Scapular dyskinesis: Patterns, functional disability and associated factors in people with shoulder disorders.
BACKGROUND
Patterns of scapular dyskinesis have unique scapular kinematics and associated muscular activation. The characteristics of unique dyskinesis patterns may be associated with functional disability.


OBJECTIVE
To investigate whether the shoulder function level and primary dysfunction items were different in unique dyskinesis pattern. The factors associated with shoulder dysfunction in different dyskinesis patterns were identified.


METHODS
Cross-sectional study.


METHODS
Fifty-one 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), shoulder range of motion 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/lower trapezius and serratus anterior muscles) during arm elevation were analyzed for associations with functional disability.


RESULTS
We found FLEX-SF scores and primary dysfunction items were similar among the patterns of dyskinesis. In inferior angle prominence, increased shoulder function was associated with decreased upper trapezius activity (R2= 0.155, p = 0.035), which accounted for approximately 16% of the variance of FLEX-SF scores. In medial border prominence, increased shoulder function was associated with increased lower trapezius activity (R2= 0.131, p = 0.017), which accounted for approximately 13% of the variance of FLEX-SF scores.


CONCLUSIONS
Upper and lower trapezius activities are important to consider in the evaluation of patients with pattern I and II, respectively. No other factors were related to shoulder dysfunction due to insufficient challenge of arm elevation tasks.
School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan.
Tsun-Shun
TS
Huang
School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan.
Chien-Ying
CY
Huang
School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan.
Hsiang-Ling
HL
Ou
School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan; Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, Taipei, Taiwan. Electronic address: jiujlin@ntu.edu.tw.
Jiu-Jenq
JJ
Lin
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D020820:Dyskinesias / Q000503:physiopathology*; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology*; D012540:Scapula / Q000503:physiopathology*; D019534:Shoulder Impingement Syndrome / Q000503:physiopathology*; D064171:Superficial Back Muscles / Q000503:physiopathology*
Function; Predictive factor; Scapular dyskinesis