Scapular Dyskinesis: The Kibler Classification and Serratus Anterior Retraining
In short
Scapular winging alters the glenoid platform angle and narrows the subacromial space; progressive serratus anterior punches restore dynamic upward rotation.
In this guide (4 sections)
The Scapula as the Engine of Shoulder Biomechanics
The scapula serves as the vital bridge linking the trunk and core to the upper extremity, transferring kinetic energy generated from the lower body to the arm. Normal overhead arm elevation requires coordinated 3D movement of the scapula: upward rotation (approximately 50 degrees), posterior tilt (approximately 30 degrees), and external rotation.
Scapular dyskinesis is an alteration in normal scapular resting position or dynamic motion during arm elevation or lowering. Rather than a distinct injury, it represents a mechanical dysfunction that contributes to secondary rotator cuff tendinopathy, labral tears, and shoulder impingement.
The Kibler Classification System for Scapular Dyskinesis
| Kibler Classification | Prominent Scapular Feature | Primary Muscle Imbalance | Associated Shoulder Pathology | |
|---|---|---|---|---|
| Type I (Inferior Angle) | Inferior medial border tilts posteriorly away from ribcage | Tight pectoralis minor; weak lower trapezius and serratus | Subacromial impingement; anterior shoulder pain | |
| Type II (Medial Border) | Entire medial border projects posteriorly off thoracic wall | Severe serratus anterior weakness; rhomboid inhibition | Superior labral tears (SLAP); massive rotator cuff tears | |
| Type III (Superior Border) | Superior border of scapula elevates excessively (shoulder hitch) | Upper trapezius dominance; delayed lower trapezius firing | Rotator cuff tendinitis; chronic neck and levator scapulae spasm | |
| Type IV (Normal Symmetrical) | Scapulae move smoothly and symmetrically without winging | Balanced neuromuscular force couples | Optimal athletic performance and power transmission |
The Scapular Retraction and Assistance Tests
- Scapular Assistance Test (SAT): Examiner manually assists scapular upward rotation and posterior tilt while athlete elevates arm; immediate elimination of pain confirms impingement is driven by scapular dyskinesis.
- Scapular Retraction Test (SRT): Examiner manually stabilizes scapula in retracted position during isometric empty-can rotator cuff testing; an immediate 20% to 30% increase in supraspinatus strength verifies scapular anchor deficit.
- Serratus Anterior Dynamic Punches: Perform push-up plus on a wall or floor, followed by ceiling punches with a dumbbell in supine, focusing on protraction at 90 to 120 degrees of arm elevation.
Frequently Asked Questions
What is scapular winging?
Scapular winging happens when the edge of your shoulder blade sticks out from your back like a wing instead of lying flat against your rib cage, usually caused by weakness in your serratus anterior muscle.
How does a rogue shoulder blade cause shoulder pain?
Your shoulder blade forms the roof and socket of your shoulder joint. If it fails to rotate upward when you lift your arm, your arm bone crashes directly into the roof of the joint, crushing your rotator cuff tendons.
What is the single best exercise for waking up the serratus anterior?
The 'push-up plus' is the gold standard exercise. At the top of a standard push-up, push your chest even further away from the floor, rounding your upper back to forcefully engage your serratus anterior.
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