What is Scapular Dyskinesis?
What is Scapular Dyskinesia?
Scapular dyskinesia is a broad term used to describe a range of dysfunctional or abnormal movements of the scapula (shoulder blade). The term “dyskinesia” literally means bad or abnormal movement (“dys” = abnormal, “kinesia” = “movement”).
How can I tell the difference between Scapular Dyskinesia vs Scapular Winging?
You may have heard of the term “scapular winging” before. This term is often used to describe a form of scapular dyskinesia where the medial or lateral borders of the scapula visibly protrude outwards from the back due to a lack of strength or control of the muscles that stabilize the scapula. Although “scapular winging” is often used interchangeably with the term “scapular dyskinesia”, it is important to recognize that the formal clinical definitions are very different. In this sense, scapular winging refers to a rare, often debilitating condition caused by a failure of the stabilizing tissues that keep the scapula anchored to the rib cage due to an injury to the long thoracic nerve. As a result, there is a prominent, wing-like protrusion of the shoulder blades leading to significant functional limitations, including the inability to lift the arm beyond about 90 degrees of shoulder flexion.
This is an important distinction because based on the above definitions, scapular winging is a structural impairment that is present even at rest (when the arm is not moving), whereas scapular dyskinesia refers to abnormalities in the movement of the scapula and an accurate diagnosis requires observing the shoulder joint in motion.
How to check Scapulohumeral Rhythm:
The shoulder joint is a ball and socket joint that enables a large range of movement along multiple planes. As such, proper shoulder movement is complex and requires a variety of muscles and bones (such as the humerus, clavicle, scapula, serratus anterior, trapezius muscles, and rhomboids) to work together. This normal pattern of shoulder movement is referred to as “scapulohumeral rhythm”.
Scapular humeral rhythm describes shoulder mobility as a ratio between the motion of the humerus (upper arm bone) and the motion of the scapula (shoulder blade). Normal scapulohumeral rhythm occurs in a 2:1 ratio of humeral to scapular motion. So, with full range of motion being quantified as 180 degrees of overhead mobility, this means that approximately 120 degrees of this motion come from humeral motion and the remaining 60 degrees come from scapular rotation. Normal scapulohumeral rhythm is important for maintaining good positioning of the ball and socket joint and improving the strength and efficiency of the surrounding muscles.
If any of those structures in the shoulder or back malfunction, the scapulohumeral rhythm can be disrupted. Muscle weakness, muscle or ligament tears, strength imbalances, nerve damage, weakness in the core, and joint issues can all contribute to scapular dyskinesis.
What is Abnormal Scapular Motion?
Scapular dyskinesia is a broad term that can describe a range of different aberrant movement patterns of varying severities, however, there are some common indicators of scapular dyskinesia that are helpful to be aware of.
Asymmetrical inferior angle (“bottom point”) of the scapula: If the inferior angle is more prominent on one side or is significantly protruding upon elevation of the arm, this may indicate weakness in your serratus anterior.
Increased upward rotation of the scapula: Significantly more upward rotation in one scapula compared to the other could indicate an injury to the rotator cuff.
Decreased upward rotation of the scapula: This may indicate weakness or decreased kinesthetic awareness of the lower trapezius. If this is associated with a pinching discomfort between 80 and 120 degrees of shoulder elevation, it is a sign of shoulder impingement.
Shifting upward of the scapula: If the shoulder shrugs up during overhead movement, it may be due to weakness of the lower trapezius or overactivity/compensation of the upper trapezius.
Excessive scapular protraction: If there is significant protraction of the scapula during shoulder elevation, it could indicate that there is weakness in the rhomboids, middle trapezius, or lower trapezius.
Inability to retract the scapula: This may indicate weakness or lack of kinesthetic awareness of the lower trap.
Can Scapular Dyskinesis be fixed?
The movement of the scapula is complex and there are many anatomical structures at play. It is important to remember that every individual’s biomechanics are unique and there will be some variation in the way our shoulders and scapulae move between different people. While mild scapular dyskinesia is not usually a cause for alarm, if it’s causing you pain and preventing you from taking part in the sports and activities you enjoy, it is a good idea to seek professional advice from a physiotherapist.
Original Article by Rachel Rubin-Sarganis
Photo of Physiotherapist Warren Nicholls by @teaclimber IG