Scapular dyskinesis
Definition
Scapular dyskinesia is defined as observable alterations in the static position of scapula or abnormal patterns of motion of scapula during coupled scapulohumeral movements in relation to the thorax.
Introduction
- Due to inhibition or disorganization of activation patterns of scapular stabilizing muscles.
- Disrupts the normal rhythm of scapulohumeral motion and shoulder kinematics.
- Associated with various shoulder pathologies such as impingement, adhesive capsulitis, instability, SLAP lesions, rotator cuff injuries and acromioclavicular disorders.
- May be the cause, effect or compensation. Exact role in shoulder dysfunction unknown.
- It may exacerbate symptoms or adversely affect the outcomes of treatment.
- Other causes are pectoralis minor contracture, Glenohumeral internal rotation deficit (posterior capsule of shoulder contracture), excessive thoracic kyphosis or excessive lumbar lordosis.
- Frequently seen in athletes with shoulder injuries. It is also in asymptomatic individuals.
- Treatment directed towards underlying cause and by kinetic chain based rehabilitation protocols to restore normal muscle activation protocols.
Functions of scapula
- Provision of a stable but mobile foundation for humeral head during glenohumeral motion
- Scapulothoracic motion
- Elevation of acromion during abduction to prevent impingement of supraspinatus.
- As a link in the kinematic chain for proximal-to-distal sequencing of velocity, forces and energy of shoulder function.
Scapular kinematics
- Scapula, shoulder and humerus are either stabilized or moved during various activities to generate, absorb or transfer forces.
- To optimize function, the scapula should move in coordination with the movements of humerus to maintain the instant centre of rotation and the alignment of glenohumeral joint. This has been likened to the balancing of a ball on seals nose.