Secondary motions of the shoulder during arm elevation in patients with shoulder tightness

Yang, Jing-Lan; Lu, Tung-Wu; Chou, Feng-Ching; Chang, Chein-wei; Lin, Jiu-jenq

doi:10.1016/j.jelekin.2008.10.011

« Previous Next »Journal of Electromyography and Kinesiology
Volume 19, Issue 6 , Pages 1035-1042, December 2009

Secondary motions of the shoulder during arm elevation in patients with shoulder tightness

Jing-Lan Yang
- Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, Taipei City 100, Taiwan, ROC
Tung-Wu Lu
- Institute of Biomedical Engineering, National Taiwan University, Taiwan, ROC
Feng-Ching Chou
- Institute of Biomedical Engineering, National Taiwan University, Taiwan, ROC
Chein-wei Chang
- Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, Taipei City 100, Taiwan, ROC
Jiu-jenq Lin
- Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, Taipei City 100, Taiwan, ROC
- School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Floor 3, No. 17, Xuzhou Road, Zhongzheng District, Taipei City 100, Taiwan, ROC
- Corresponding author. Address: School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Floor 3, No. 17, Xuzhou Road, Zhongzheng District, Taipei 100, Taiwan, ROC. Tel.: +886 2 33228126; fax: +886 2 33228161.

Received 25 April 2008; received in revised form 25 August 2008; accepted 7 October 2008. published online 17 December 2008.

Abstract

An analysis of secondary shoulder motions (humeral rotation, humeral head anterior/posterior translation, scapular tipping, and scapular upward/downward rotation) in subjects with anterior/posterior shoulder tightness provides the opportunity to examine the role of tightness as a means of affecting shoulder motions. Subjects with shoulder tightness (anterior, n=12; posterior, n=12) elevated their arms in the scapular plane. Three replicated movements were performed to the maximum motions. Kinematics data were collected by FASTRAK 3D electromagnetic system. To determine if a significant difference of the secondary motions existed between anterior/posterior shoulder tightness, two-factor mixed ANOVA models with the repeated factor of elevation angle (five elevation angles) and the independent factor of group were calculated. The relationships between the self-reported functional scores (Flexilevel Scale of Shoulder Function, FLEX-SF) and abnormal shoulder kinematics were assessed. For humeral head anterior/posterior translation, the subjects with posterior tightness demonstrated anterior humeral head translation (10mm, p=0.019) compared to subjects with anterior tightness. The subjects with anterior tightness demonstrated less posterior tipping (2.2°, p=0.045) compared to subjects with posterior tightness. The humeral anterior translation had moderate relationships with FLEX-SF scores (r=−0.535) in subjects with posterior tightness. The scapular tipping had moderate relationships with FLEX-SF scores (r=0.432) in subjects with anterior tightness. In conclusion, the secondary motions were different between subjects with anterior and posterior shoulder tightness. During arm elevation, less scapular posterior tipping and less posterior humeral head translation in subjects with anterior and posterior shoulder tightness, respectively, are significantly related to self-reported functional disability in these subjects.