A winged scapula, medically termed scapular winging, is a condition where the shoulder blade, or scapula, protrudes noticeably from the back instead of lying flat against the chest wall. The name comes from the bone’s border sticking out, resembling a bird’s partially extended wing. This abnormal position interferes with the shoulder’s natural function, often leading to weakness, pain, and a restricted range of motion in the arm. The condition indicates a loss of stability in the complex system of muscles and nerves that secure the shoulder blade.
The Anatomy Behind the Condition
The scapula is held in place by a network of muscles that must work in coordination to ensure smooth arm movement. Stability is maintained by three primary muscle groups; failure in any of these muscles or their controlling nerves can result in winging. The serratus anterior muscle is the most frequently implicated stabilizer, functioning to protract the scapula and keep its medial border tightly against the rib cage. This muscle is innervated by the long thoracic nerve, which is uniquely vulnerable to injury.
When the long thoracic nerve is impaired, the resulting weakness of the serratus anterior causes pronounced “medial winging,” where the shoulder blade’s inner edge lifts away from the back. The trapezius, a large muscle responsible for elevating, depressing, and retracting the scapula, is also involved. Trapezius paralysis, usually due to spinal accessory nerve damage, results in “lateral winging,” causing the shoulder to droop and the outer part of the scapula to move abnormally.
The rhomboid muscles (major and minor) also play a role in retraction and stabilization, pulling the scapula toward the spine. These muscles are innervated by the dorsal scapular nerve. Impairment of the rhomboids is a less frequent cause of winging, resulting in a more subtle form of lateral protrusion. The specific pattern of winging—medial or lateral—provides a clear clue as to which nerve-muscle unit has been affected.
Common Causes of Scapular Winging
The loss of nerve function leading to scapular winging can be traced to several categories of injury or disease. Traumatic events are a common source, including direct blunt force trauma to the shoulder or chest, falls, and overstretching injuries. Repetitive strain from activities, such as heavy overhead lifting or throwing sports, can also cause traction injury to the long thoracic nerve.
A significant number of cases are classified as iatrogenic, meaning the injury occurred as a result of a medical procedure. The spinal accessory nerve is susceptible to damage during neck surgeries, such as lymph node biopsies or excisions of masses. The long thoracic nerve can also be injured during chest wall surgery, including mastectomies or certain cardiothoracic procedures.
Non-traumatic neurological causes often involve inflammatory conditions that affect the peripheral nerves. Viral illnesses, including mononucleosis and influenza, have been implicated in the onset of nerve damage. Furthermore, Parsonage-Turner Syndrome (neuralgic amyotrophy), which causes inflammation of the brachial plexus nerves, can lead to sudden, painful paralysis of the scapular muscles.
Diagnosis and Management Strategies
Identifying a winged scapula begins with a physical examination, where a physician observes the shoulder blade’s movement and position. The wall push-up test is used to confirm serratus anterior weakness, as the scapula protrudes noticeably when the patient pushes against the wall. To determine neurological involvement, Electromyography (EMG) and Nerve Conduction Studies (NCS) are utilized. These tests measure the electrical activity in the muscles and nerves, confirming nerve damage and helping to estimate the extent of the injury.
Initial management is typically conservative, particularly in cases linked to nerve injury, because many conditions resolve spontaneously over six months up to two years. Physical therapy is a primary component of conservative care, focusing on strengthening the remaining scapular stabilizer muscles and correcting postural issues. Pain is managed with anti-inflammatory medications, and activity modification is advised to avoid aggravating the condition.
When conservative treatments fail to provide sufficient recovery after an extended period, or in cases of severe trauma, surgical intervention may be considered. Surgical options are tailored to the specific nerve or muscle affected. For chronic serratus anterior palsy, a tendon transfer, such as moving the pectoralis major muscle to the scapula, can restore function. Nerve decompression or nerve grafting procedures are reserved for acute nerve injuries that show no signs of improvement.