Does your shoulder blade pop or snap when reaching overhead? Snapping scapula syndrome is a somewhat rare condition that typically affects overhead athletes. It is a snapping or grinding that can be located between the shoulder blade and the rib cage. The soft tissues between the scapula and the chest wall can become inflamed or irritated. Snapping scapula syndrome can also occur if the scapula or rib cage grate on each other. 

There are a few conditions that will lead to snapping scapula syndrome. The space between the shoulder blade and the rib cage is called the scapulothoracic joint. Anything that causes friction in this area can cause the snapping sensation. The name ‘scapulothoracic joint’ is a misnomer as it is not a true joint. The scapula ‘floats’ on top of musculature that overlays the rib cage, namely the subscapularis and serratus anterior. Variations in bone structure, muscles, and bursa can cause snapping scapula syndrome. 

We all have our anatomic variations, and in the scapula, there is one variation that has been attributed to a snapping scapula. If you look at the scapula from the side, there is an angle from the ‘blade’ of the scapula and the top part of it. In a sample population, this angle varied from 124 degrees to 162 degrees. When the angle is lower than 142 degrees, the chances for a snapping scapula increase (Carvalho et al., 2019).

Any factor that decreases the space between the scapula and rib cage can cause irritation and potentially snapping. Muscle imbalances or atrophy can lead to this. The two muscles underneath the scapula are the subscapularis and the serratus anterior. The serratus anterior is commonly found to be weak and inadequate and should be assessed. 

There is also a bursa between these muscles called the supraserratus bursa. Just like any bursa, it can become inflamed with repetitive overuse or through trauma. When it’s inflamed, it will cause friction in this narrow space and lead to snapping. 

Finally, although rare, it is possible to form tumors in this space; both benign or malignant. With this in mind, it is best to seek a consultation with a physician and potentially an image of the area to rule out any insidious pathology. 

References:

Carvalho, S. C. D., Castro, A. D. A. E., Rodrigues, J. C., Cerqueira, W. S., Santos, D. D. C. B., & Rosemberg, L. A. (2019). Snapping scapula syndrome: pictorial essay. Radiologia Brasileira, 52(4), 262–267. doi: 10.1590/0100-3984.2017.0226