Pectus Carinatum (PC), also widely known as “pigeon chest,” is a common congenital deformity of the anterior chest wall. The name is derived from the Latin word carinatum, meaning “keel,” describing the abnormal outward projection of the breastbone. This protrusion typically becomes more prominent during periods of rapid growth.
The Structural Basis of Pectus Carinatum
Pectus Carinatum involves the sternum (breastbone) and the adjacent costal cartilages which connect the ribs. The deformity is defined by the outward displacement of these structures, creating a convex or bulging profile on the front of the chest. This physical manifestation is the reverse of Pectus Excavatum, a more common condition where the sternum is depressed inward.
The protrusion results from an overgrowth or defect in the development of the costal cartilage. This excessive cartilage growth acts like a spring, pushing the sternum forward from the inside of the chest cavity. In the most frequent subtype, known as chondrogladiolar prominence, the middle and lower portions of the sternum are pushed forward. The resulting projection can be symmetrical, or it can be asymmetrical, with one side protruding more noticeably than the other.
Etiology and Associated Genetic Factors
The precise cause for the development of Pectus Carinatum is often considered idiopathic, meaning the cause is generally unknown. However, the prevailing theory centers on an intrinsic growth disturbance affecting the costal cartilage, which leads to its abnormal proliferation. This disproportionate growth forces the bony structures of the chest wall into their projected position.
A genetic predisposition is recognized, with estimates suggesting that up to 40% of affected individuals have a family member with Pectus Carinatum or a related chest wall deformity. The condition is strongly associated with certain connective tissue disorders, which affect the body’s structural proteins. Examples include Marfan syndrome and Ehlers-Danlos syndrome, which involve widespread abnormalities in connective tissues.
Although the deformity is present from birth, it often becomes significantly more noticeable during the rapid growth phase of adolescence, typically between the ages of 11 and 14. This pubertal growth spurt causes the underlying cartilage issue to manifest more dramatically as the entire skeletal structure rapidly increases in size. The male-to-female ratio is notably skewed, with males being affected far more frequently than females.
Diagnosis and Treatment Modalities
Diagnosis is primarily achieved through a thorough physical examination, as the outward protrusion is visually distinct. A physician will observe the chest wall, often while the patient is standing, to assess the location, symmetry, and degree of the sternal projection. While the physical exam establishes the diagnosis, imaging studies are often utilized to provide a quantitative assessment of the condition’s severity.
A chest X-ray helps rule out other skeletal abnormalities, such as scoliosis, which is sometimes concurrently present. Computed Tomography (CT) scans offer a detailed cross-sectional view of the chest, used to precisely measure the degree of protrusion and determine the relationship between the sternum and the internal organs. In more severe presentations, specialized tests like an echocardiogram and pulmonary function tests may be ordered to evaluate the impact of chest wall rigidity on heart and lung function.
Management is divided into non-surgical and surgical options, with the choice depending on the patient’s age, the severity of the protrusion, and the flexibility of the chest wall. The primary non-surgical treatment is an external compression brace, which is highly effective in younger patients whose cartilage is still pliable. This custom-fitted orthotic brace applies continuous, gentle pressure to the protruding sternum to gradually remodel the chest wall over a period that typically lasts one to two years.
Surgical correction is reserved for severe cases, patients who have not responded to bracing, or individuals experiencing functional impairment or psychological distress. The modified Ravitch procedure is a common surgical technique, which involves removing the abnormally grown costal cartilage to allow the sternum to be repositioned and secured in a normal alignment. Minimally invasive surgical techniques are also increasingly utilized, offering an alternative for reducing the extent of the operation and shortening the recovery time.