Scapula alata

Scapula alata is an abnormal outward position of the shoulder blade. Scapula alata literally means ‘winged shoulder blade’. A scapula alata is generally not a condition in itself but a sign that there is a disturbance in the nerve supply to the muscle or that there is an imbalance between the muscles.

How does a scapula alata arise?

The abnormality can occur when one of the shoulder girdle muscles does not function properly. In most cases, reduced nerve supply is responsible for the muscle function.
A reduced nerve function can be the result of nerve damage, caused by, for example, an accident or a (bacterial) infection.

Reduced muscle function can also be locally caused by, or be a consequence of, for example, a shoulder bursitis or subacromial pain syndrome.

In rare cases, a scapula alata is a consequence of a more serious condition, for example, Parsonage-Turner syndrome. This is an inflammation of the brachial plexus, the nerve bundle at the shoulder.

What are the features (symptoms) of a scapula alata?

The most characteristic symptom is the protruding position of the shoulder blade. Two different forms can be distinguished. The protrusion of the inner border, along the spine, is referred to as winging. The protrusion of the upper border (shrugging) and the protrusion of the lower tip of the shoulder blade is called tipping.

The degree of protrusion mainly depends on the remaining innervation of the involved nerve and muscles. The altered position of the shoulder blade limits the freedom of movement of the shoulder girdle and the shoulder. The shoulder girdle is the group of bones that connects the arm to the rest of the skeleton (collarbone and shoulder blade).

How is a scapula alata diagnosed?

On inspection and physical examination of the shoulder girdle by a physical therapist, the movement pattern of the shoulder blade can show an abnormal pattern. In the medical field, this is called scapular dyskinesia.

Additional tests such as an MRI scan or a CT scan are rarely necessary, but can be used as imaging to exclude other underlying (more serious) conditions if needed.

What is the treatment for a scapula alata?

Treatment is aimed at restoring muscle function. Relearning a correct movement pattern of the shoulder blade is the starting point. It is wise to enlist the help of a physical therapist. They will mainly focus treatment on exercise therapy and strength training, while also monitoring the mobility of the shoulder and shoulder girdle.