Shoulder Brace on Muscle Activation and Scapular Kinematics in Patients With Shoulder Impingement Syndrome and Rounded Shoulder Posture

Background: Rounded shoulder posture (RSP), associated with altered scapular kinematics and imbalance of muscle activation, 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 activation and scapular kinematics in patients with SIS and RSP. Objective: There are 4 objectives for the present study: (1) to investigate the relationships among degree of RSP, scapular kinematics and muscle activation in SIS patients with RSP; (2) to compare the effect of shoulder brace on degree of RSP, muscle balance ratios (Upper trapezius/Lower trapezius, Upper trapezius/ Serratus anterior) and scapular kinematics (upward/downward rotation, anterior/posterior tilt, external/internal rotation) during arm movements; (3) to compare the effect of two tensions of brace strap (self-comfortable and forced tension) in symptomatic impingement patients with RSP; (4) to compare the effect of two types of direction of strap (paraspinal muscle and diagonal orientation) in symptomatic impingement patients with RSP. Design: Patients with SIS and RSP will be recruited in this study. Participants will be 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 patient has the assessment 2 times with 1-week interval. Pectoralis minor, acromial distance, scapular index and shoulder angle will be used to assess degree of RSP. Three-dimensional electromagnetic motion analysis and electromyography muscle activity will be used to record the scapular kinematic, absolute muscle activation and muscular balance ratios during arm movements with or without shoulder brace. Main outcome measures: Scapula kinematic (upw