Identification of proximal-caused scapular dyskinesis in subacromial impingement and its clinical and motion characteristics

• Main Authors: Qi-Xing Chang, 張棋興
• Other Authors: Wen-Yin Chen
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/40636996097987127109

碩士 === 國立陽明大學 === 物理治療暨輔助科技學系 === 100 === Background: Scapular dyskinesis is believed to be one causative factor in subacromial impingement syndrome (SIS). Different scapular kinematics was present in previous SIS studies. Reduction in scapular upward rotation (UR), posterior tilt (PT) or external rotation (ER) on scapular kinematics and increased upper treapezius (UT) electromyographic (EMG) activity, decreased lower trapezius (LT) EMG activity or serratus anterior (SA) EMG activity during arm elevation is contributory to the impingement mechanism and can be termed as the proximal-caused scapular dyskinesis (PCSD). However, the validity of scapular dyskinesis screening test such as scapular assistance test (SAT) and scapular retraction test (SRT) was not established, and the clinical and motion characteristics of PCSD were unclear. Purposes: The purposes of the study were to determine (1) the inter-rater reliability and intra-rater reliability of the SAT and SRT, and (2) the construct validity of the two clinical tests through examinating the discriminant validity and hypothesis testing, and (3) clinical and motion characteristics of PCSD inSIS. Methods: First of all, two testers evaluated 12 subjects with SIS separately to exam the inter-rater reliability. One tester evaluated 17 subjects with SIS twice with an interval of 30 minutes for examining the intra-rater reliability. Their results were assessed with weighted kappa and percentage of agreement for estimating inter-rater and intra-rater reliability of SATand SRT. We recruited 44 subjects with SIS and collected data on clinical characteristics such as joint mobility, muscle strength, and posture. Then we collected data on motion characteristics including scapular kinematics and muscle activation. After that, we applied scapular taping to all subjects for correcting PCSD. The motion characteristics were collected again after the taping. We used SAT and SRT to divide the subjects into a PCSD positive and a negative group, then compared the difference in clinical and motion characteristics, as well as the improvement after taping between the two groups using analysis of covariance with repeated measures. Results and Discussion: The inter-rater reliability (Kw=0.75, agreement=91.7%) and intra-rater reliability (Kw＝0.87, agreement=94.1%) of SAT and SRT were substantial. Among the 44 subjects with SIS, half were tested positive and the other half negative. The two groups showed no difference in the basic data except pain duration (p=0.04). The positive group revealed sighificantly decreased scapular UR ( p<0.01), and reduced activation in LT ( p=0.03) and SA ( p=0.02), a features matching the motion characteristics of PCSD; thereby establishing the discriminant validity of the tests. After scapular taping, the positive group showed significantly more increase in UR (p<0.01), as well as activation of LT (p=0.02) and SA (p=0.04), which supported the hypothesis that subjects with PCSD would improve more with an intervention that is know to benefit scapular control. Conclusion and clinical relevance: We have established the reliability and construct validity of the scapular dyskinesis test, which could help to screen subjcts with PCSD that possessed specific clinical and motion characteristics. Appropriate treatments could be administered to help scapular control for these subjects.