肩帶對於肩夾擠症候群伴隨圓肩的個人在肌肉活性與肩胛骨動態的立即性影響

Abstract

背景：圓肩是肩夾擠症候群潛在的危險因子之一，其成因在於圓肩通常伴隨肩胛骨動作的改變和不平衡的肌肉活性，進而導致肩胛骨位置偏移。過往研究提及肩帶可以藉由姿勢改變的方式改善圓肩的程度, 但目前仍不清楚不同的肩帶特性（張力與方向性）是否對於肩夾擠症候群伴隨圓肩的患者在肌肉活性和肩胛骨動作上有正向的影響。實驗目的：本實驗有兩個目的:(1) 針對肩夾擠伴隨圓肩的族群，比較肩帶有無在臨床圓肩評估、肌肉活性和肩胛骨動作上的影響, (2) 比較兩種肩帶張力和兩種方向的肩帶對於肌肉活性、肌肉平衡比例和肩胛骨動作在手臂動作過程中的影響。實驗設計：共招募24位受試者並隨機分配到兩組進行不同張力、不同方向肩帶的穿戴，觀察其在不同穿戴條件下，其肌肉活性、肌肉平衡比例和肩胛骨動作的變化，每位受試者共參與兩次測試，兩次測試間隔一週。本實驗使用胸小肌指數、肩峰距離、肩胛骨指數和肩關節角度評估圓肩程度;使用三維電磁動作分析儀和肌電圖紀錄不同肩帶條件下，其肩胛骨動作與肌電訊號。 主要測量項目：肩胛骨動作（上/下旋、前/後傾、內/外轉），絕對肩胛骨肌肉活性（上斜方肌、中斜方肌、下斜方肌、前鋸肌）和肌肉活性比值（上斜方肌/ 下斜方肌、上斜方肌/ 前鋸肌）。結果：所有圓肩的臨床評估在穿戴肩帶後都有明顯改善，包含疼痛指數與肩關節功能性量表;針對較高張力下的肌肉活性，下斜方肌與前鋸肌的肌肉活性在斜向方向比在平行方向高，上斜方肌/ 下斜方肌的肌肉活性比值則是斜向方向小於平行方向; 針對較高張力下的肩胛骨動作，肩胛骨上旋與後傾的角度在斜向方向大於平行方向，肩胛骨內轉則是斜向方向小於平行方向。結論：建議有肩夾擠症候群伴隨圓肩的個人，可以使用斜向且張力介於舒適與較強之間的肩帶來改善症狀與圓肩程度。

Background: Rounded shoulder posture (RSP), associated with altered scapular kinematics and imbalance of muscle activity, is one of potential risks for shoulder impingement syndrome (SIS) due to alignment deviation of scapula. Evidence showed shoulder brace improved degree of RSP by postural correction. However, it is unknown whether shoulder brace with different characteristics (tension and direction) is optimal for muscle activity and scapular kinematics in patients with SIS and RSP. Objective: The purposes of this study were to (1) compare the effect of shoulder brace (no-brace and comfortable/forced diagonal brace) on clinical RSP measurements, muscle activities and scapular kinematics in subjects with SIS and RSP; (2) compare the effect of two directions (paraspinal muscle and diagonal orientation) and two tensions (self-comfortable and forced tension) of strap on muscle activities, muscle balance ratios and scapular kinematics during arm movements in subjects with SIS and RSP. Design: Twenty-four participants with SIS and RSP were recruited and randomly assigned into 2 groups (self-comfortable following forced tension and forced following self-comfortable tension groups) with 2 directions of strap in each tension wearing shoulder brace. Each subject had the assessment 2 times with 1-week interval. Pectoralis minor index (PMI), acromial distance (AD), scapular index (SI) and shoulder angle (SA) were used to assess degree of RSP. Three-dimensional electromagnetic motion analysis and electromyography muscle activity were used to record the scapular kinematics, absolute muscle activity and muscular balance ratios during arm movements with or without shoulder brace. Main outcome measures: Scapular kinematics (upward/downward rotation, anterior/posterior tilt, external/internal rotation), absolute muscle activity (UT, MT, LT, SA) and muscle balance ratios (UT/LT, UT/SA) were main outcomes of the study. Results: All clinical measurements with the brace were significantly improved, including VAS, AD, PMI, SI, SA and FLEX-SF (p< 0.05). For muscle activities under forced tension, muscle activities were higher in diagonal brace than those in parallel brace for LT (1.2~2.3%MVIC, p< 0.05) and SA (2.3%MVIC, p= 0.015) while UT/LT muscle balance ratio were lower in diagonal brace than those in parallel brace (0.39, p= 0.019). For scapular kinematics under forced tension, upward rotation and posterior tilting of the scapula in diagonal direction were larger than those in parallel direction (1.5°, p= 0.038; 0.4°~0.5°, p< 0.05, respectively). For internal rotation under forced tension, degree of scapular kinematics in diagonal direction brace were less than those in parallel direction (1°~1.8°, p< 0.05). Conclusion: The application of shoulder brace with diagonal orientation and tension between comfortable and forced is suggested for SIS subjects with RSP.