Pectus Carinatum, often called “pigeon chest” or “keel chest,” is a chest wall deformity characterized by an outward protrusion of the sternum, or breastbone. This condition results in a prominent anterior chest contour, distinct from the inward depression seen in Pectus Excavatum. This article provides a comprehensive overview of this structural variation and its frequency.
Understanding the Anatomy of Pectus Carinatum
Pectus Carinatum (PC) arises from an abnormal growth of the costal cartilages, the flexible strips of tissue connecting the ribs to the sternum. This overgrowth forces the sternum forward in a convex manner, creating the characteristic bowed-out appearance. The issue lies with the cartilage, not the bones themselves.
The condition is classified into two main anatomical types based on the location of the protrusion. The most common form (up to 95% of cases) is the chondrogladiolar type, where the middle and lower parts of the sternum are pushed forward. The much rarer chondromanubrial type involves the protrusion of the upper sternum, a more complex area to treat. The etiology is often linked to genetic predisposition, sometimes running in families or associated with connective tissue disorders like Marfan syndrome.
Prevalence and Demographics
Pectus Carinatum is the second most common chest wall deformity, following Pectus Excavatum. The estimated incidence rate varies, but it is generally reported to affect approximately 1 in 1,000 to 1 in 2,000 live births. This makes it less frequent than Pectus Excavatum.
Pectus Carinatum shows a strong male predominance, affecting males four to seven times more frequently than females (a ratio often cited as 4:1). Although the predisposition is present at birth, the deformity most commonly becomes noticeable or worsens during periods of rapid skeletal growth. The typical age of presentation is in early adolescence, often between 11 and 15 years, coinciding with the pubertal growth spurt.
Functional and Psychological Impact
While Pectus Carinatum is largely considered a cosmetic deformity, it can produce both functional and psychological consequences. Physical symptoms are often mild, but some individuals report chest pain, tenderness in the area of cartilage overgrowth, or reduced exercise tolerance. The altered chest wall mechanics can occasionally lead to breathlessness on exertion or “asthma-like” symptoms.
The psychological impact often outweighs the physical symptoms and is frequently the primary reason patients seek medical intervention. The visible nature of the protrusion can lead to significant body image distress, self-consciousness, and reduced self-esteem, particularly among adolescents. Affected individuals may avoid activities that require them to expose their chest, such as swimming or gym class, restricting social engagement. Patients with Pectus Carinatum often experience a decrease in mental quality of life and dissatisfaction with their appearance.
Management Approaches
The treatment approach depends on the patient’s age, skeletal flexibility, and the severity of the protrusion. Non-surgical management, primarily through the use of an external chest brace, is generally the first-line treatment for growing adolescents. This custom-fitted orthotic applies sustained pressure to the most prominent part of the chest, gradually pushing the sternum back into a corrected position.
Bracing is highly effective, with reported success rates exceeding 90% when worn as directed, particularly for patients whose chest wall is still flexible. Treatment typically requires wearing the brace for many hours a day over a period of six to twelve months, or sometimes longer. Surgical correction, such as the modified Ravitch procedure, is reserved for severe cases, those with rigid chest walls that do not respond to bracing, or when the patient has reached skeletal maturity. These techniques involve removing the abnormally grown costal cartilage to allow the sternum to be repositioned, offering a definitive solution when non-invasive methods are not viable.