The chest wall, formed by the sternum, ribs, and connecting cartilage, provides essential protection for the heart and lungs. Changes to the contour of this structure, particularly an outward protrusion of the breastbone, are a common reason for seeking medical advice. These variations are often developmental, relating to the growth process of the underlying skeletal framework.
Pectus Carinatum The Primary Cause of Protrusion
The most frequent explanation for a protruding chest bone is Pectus Carinatum (PC), often called “pigeon chest.” This structural malformation involves the sternum and ribs being pushed forward, creating a convex appearance on the anterior chest wall. The underlying cause is an abnormal overgrowth of the costal cartilages, the flexible tissues connecting the ribs to the sternum.
As the cartilage expands, it exerts pressure on the sternum, forcing it to bow outward from the body’s midline. Pectus Carinatum is considered a congenital deformation, present from birth, though it may not be visually obvious until later in childhood. It typically becomes most noticeable during periods of rapid skeletal growth, especially the adolescent growth spurt.
Pectus carinatum is observed more frequently in males than in females, with a ratio estimated to be as high as four to one. While the exact cause remains unknown, a strong genetic component is suggested by the fact that nearly one-quarter of affected individuals report a family history of a chest wall abnormality. The protrusion itself can be symmetrical, involving the entire sternum, or asymmetrical, where one side of the chest appears more prominent than the other.
Distinguishing Pectus Carinatum from Other Conditions
Pectus Carinatum is often contrasted with its most common counterpart, Pectus Excavatum, or “funnel chest.” These two deformities are anatomical opposites: Pectus Excavatum is characterized by an inward depression of the sternum, while Pectus Carinatum presents with an outward protrusion. Both conditions stem from issues with costal cartilage growth but result in different chest shapes.
Less common causes of localized chest protrusion or swelling must also be considered. For instance, Tietze syndrome is an inflammatory condition causing painful swelling of the costal cartilage, usually affecting a single joint near the sternum. Unlike the developmental nature of Pectus Carinatum, Tietze syndrome is an acquired issue marked by active inflammation and tenderness.
Pectus Carinatum has been linked to other musculoskeletal issues, such as scoliosis (a lateral curvature of the spine). The condition is also seen in association with certain connective tissue disorders, including Marfan syndrome. A proper evaluation by a specialist is necessary to differentiate accurately between a primary chest wall deformity, an inflammatory process, or a manifestation of a broader systemic condition.
Symptoms Beyond Appearance
While the defining characteristic of Pectus Carinatum is the visual protrusion, the condition can lead to other physical and psychological effects. In moderate to severe cases, the rigidity caused by the displaced chest wall can impair the mechanical efficiency of breathing. This limitation may manifest as shortness of breath or reduced stamina, particularly during strenuous physical activity.
Some patients report experiencing mild, localized discomfort, chest pain, or tenderness in the area of cartilage overgrowth. The altered chest shape can also contribute to postural problems, such as rounded shoulders or an exaggerated upper back curve. However, many individuals with Pectus Carinatum are physically asymptomatic, experiencing no functional limitations related to the deformity.
The most significant impact often revolves around the psychological and social consequences of the visible deformity. Teenagers and young adults may develop self-consciousness, body image concerns, or reduced self-esteem. These psychological factors can sometimes lead to avoidance of social situations or activities where the chest is exposed, such as swimming or gym class.
Medical Assessment and Management Options
Addressing a protruding chest bone begins with a thorough physical examination by a healthcare provider, often a specialist in chest wall deformities. This clinical assessment usually confirms the diagnosis of Pectus Carinatum. Further diagnostic imaging is utilized to evaluate the severity of the protrusion, assess chest wall flexibility, and determine any potential impact on internal organs.
Imaging tests typically include a chest X-ray to visualize the skeletal structure and sometimes a computed tomography (CT) scan to provide a detailed, cross-sectional view of the chest. The CT scan is particularly useful for measuring the degree of compression or displacement of the heart and lungs, though functional impairment is rare with this condition. For mild, asymptomatic cases, a specialist may recommend simple observation to monitor the protrusion’s progression over time.
For more pronounced cases, non-surgical treatment with external bracing is the standard first-line therapy, especially for growing adolescents with flexible chest walls. The brace is a custom-fitted orthotic device that applies continuous, firm pressure directly to the protruding sternum. Similar to dental braces, this sustained force gradually remodels the malleable costal cartilage and reshapes the chest wall into a more typical contour.
Patients must wear the dynamic compression brace consistently, typically for 12 to 23 hours per day, for a period ranging from several months to over a year. Bracing is highly effective, with success rates often exceeding 80% in compliant patients who start treatment early. Surgical correction, such as a modified Ravitch procedure, is reserved for older patients with rigid chests, severe deformities, or cases where bracing was unsatisfactory.
The modified Ravitch procedure is an open operation involving an incision to remove the overgrown sections of costal cartilage. The surgeon then repositions the sternum and may temporarily place a support bar to hold the breastbone in the corrected position while the chest wall heals. This surgical approach ensures a permanent correction but is typically considered only after less invasive methods have been exhausted or are unsuitable due to skeletal maturity.