Shoulder Impingement Syndrome – Contributing Factors and Management
The primary function of the rotator cuff (RC) muscles is to stabilize, compress and provide fine motor control to the glenohumeral joint. The supraspinatus acts to compress the humeral head into the glenoid fossa and prevent excessive superior translation of the humeral head during functional activities. The subscapularis acts to prevent excessive anterior and superior translations of the humeral head, which is one of the leading biomechanical causes of impingement syndromes (Sarhmann, 2002). The infraspinatus and teres minor act to prevent excessive superior and posterior translations during activity.
The subacromial space houses the supraspinatus tendon, subacromial bursa and the biceps tendon.
Factors that affect the subacromial space:
– anatomical variation: shape and size of the acromion or presence of osteophytes
– previous shoulder trauma that disrupts the stabilizing mechanisms of the joint, affecting the firing patterns of the RC muscles
– altered scapular positions due to muscles tightness, imbalance or poor stabilizer recruitment patterns
Postural faults, scapular dyskinesis and muscular imbalance can also lead to RC impingement. Shortening and tightness of pectoralis minor can cause the scapula to sit in a downwardly rotated position at rest, bringing the acromion process closer to the humeral head (Borstad, 2004). Poor thoracic spine extension causes the scapula to be further protracted and downwardly rotated thus limiting the mobility of the scapulothoracic complex (Borstad, 2006).
Typically, the subscapularis and supraspinatus need to be strengthened to reduce anterior and superior translation of the humeral head. Coupled with this, the posterior cuff with an overactive ingraspinatus and tight posterior capsule need to be released. Through specific neural and strength retraining, physiotherapy can influence the firing patterns of the RC as dynamic stabilizers and use manual therapy and/or needling techniques for the posterior cuff. Furthermore, the physiotherapist can address the scapular kinetics, releasing and stretching muscles causing downward rotation (the pec minor and levator scapulae) and strengthening muscles that work to upwardly rotate the scapula (serratus anterior). The physiotherapist will also address postural faults including thoracic hypomobility via mobilization/manipulation and postural endurance retraining of the rhomboids and middle and lower trapezius. For more information, please contact us at the clinic by phone or email and ask to speak to one of our physiotherapists.