A 14-year-old girl presented with concerns about a "deformed" right shoulder. Despite the fact that there was no associated weakness, the defect made her self-conscious. She denied recent trauma to the site and severe physical exertion.
The parents first noticed their daughter's protuberant back bones during gymnastics and dance classes when she was 4 years old. There were never any associated symptoms, however.
Atiya Khan, MD, and Tracy Weimer, MD, of Morgantown, WVa, diagnosed congenital bilateral scapular winging, which was more prominent in the right shoulder than in the left. There was no associated bony abnormality of the spine or clavicle. An MRI scan of the right shoulder showed hypoplasia of the right serratus anterior and mild diminution of the right latissimus dorsi.
The serratus anterior covers much of the lateral aspect of the thorax. Its origin has a serrated appearance, since it arises from the outer surfaces of the upper 8 and 9 ribs. The muscle attaches along the medial border of the scapula and holds the scapula against the thoracic wall. It is innervated by the long thoracic nerve.
Winging of the scapula may be acquired or congenital and may affect the nerves, skeletal system, or joints. Nerve damage--the chief acquired cause--may be a result of compression, trauma, or iatrogenic injury during surgery. The long thoracic nerve is classically involved; however, damage to the spinal accessory nerve or brachial plexus may also produce scapular winging. Other acquired causes include musculoskeletal trauma and degenerative and inflammatory joint disease.1 Amyotrophic brachial plexopathy may produce winging via an autoimmune process. Winged scapula secondary to an allergic response to benzylpenicillin has been reported.2
Congenital causes include hypoplasia and the absence of muscles involved in scapular stabilization. Absence of the serratus anterior alone and in combination with other muscles has been reported.3 The hypoplasia of both the serratus anterior and latissimus dorsi in this patient may represent one end of the spectrum of Poland syndrome--a rare congenital anomaly characterized by chest wall hypoplasia and theoretically caused by hypoplasia of the subclavian artery and its branches.4 Skeletal deformities such as scoliosis and cleidocranial dysostosis are other congenital causes of scapular winging.
In patients with shoulder pain, carefully evaluate scapulothoracic motion and function. The scapular stabilization test--in which the scapula is manually compressed against the chest wall during arm movement--can confirm shoulder pain caused by scapular hypermobility. The test is diagnosticwhen it relieves pain and improves the patient's ability to elevate the shoulder.5
The finding of a winged scapula should prompt a diagnostic workup. It is useful to classify scapular winging as static or dynamic. Static winging is present at rest and is generally a result of a fixed deformity. Dynamic winging is associated with only active or resistive movements and is more likely a result of a neuromuscular disorder.1 An electromyogram may be required to confirm nerve damage, and imaging studies may be required to identify skeletal or muscular anomalies.
Serratus anterior dysfunction can be treated conservatively with braces designed to stabilize the scapula. Many patients benefit from periscapular strengthening through physical therapy. Surgery may be an option for patients with severe symptoms that do not abate after 12 months of conservative therapy.6
This patient deferred surgical correction, since she had no functional deficits.
1. Fiddian NJ, King RJ. The winged scapula. Clin Orthop Relat Res. 1984;(185):228-236.
2. Waller CJ, Hay SM. Winging of the scapula-- an unusual cause. Allergy. 2003;58:163-164.
3. Hegde HR, Shokeir MH. Posterior shoulder girdle abnormalities with absence of pectoralis major muscle. Am J Med Genet. 1982;13:285-293.
4. David TJ, Winter RM. Familial absence of the pectoralis major, serratus anterior, and latissimus dorsi muscles. J Med Genet. 1985;22:390-392.
5. Warner JJ, Navarro RA. Serratus anterior dysfunction. Recognition and treatment. Clin Orthop Relat Res. 1998;349:139-148.
6. Wiater JM, Flatow EL. Long thoracic nerve injury. Clin Orthop Relat Res. Nov 1999;(368):17-27.