Pectus carinatum is a chest wall deformity caused by an overgrowth of the costal cartilages. This causes anterior protrusion of the sternum with narrowing of the sides of the chest wall, resulting in a bowed appearance often referred to as “pigeon chest.” This deformity can occur in patients with connective tissue disorders, in association with scoliosis, in families, or sporadically in patients without any other abnormalities.
Pectus carinatum occurs in 1 of 300 births. It is more common in males by a 4:1 ratio. It is often apparent at birth, but becomes more noticeable and more severe during periods of rapid growth, such as puberty.
The varied patient population affected by pectus carinatum has led to different theories about its etiology. Most of these theories focus on an abnormality in the cartilage. Damage to the growth plates in the costochondral junction, leading to the overgrowth of the costal cartilages, is thought to be the cause among the sporadic patient population. Efforts to identify a cause in genetically linked patients have led to more intensive study of collagen synthesis and structure. Studies of skin and cartilage collagen have focused on the ratios of collagen types and the stability of collagen I and II. The consistent finding of collagen with unstabilized end terminals suggests a specific mutation, but the exact mutation has not been determined.
Associated Defects and Syndromes
Approximately 20% of patients have associated anomalies. These include numerous conditions such as cardiac defects, microcapnia, bilateral clubfeet, hemifacial microsomia, microphthalmia, tracheoesophageal fistulae, congenital laryngeal stridor, a dolichocephalic skull, scoliosis, and other musculoskeletal anomalies. The family history is positive for a chest wall deformity in approximately 25% of cases.
The incidence of pectus carinatum is higher in patients with Poland syndrome and Marfan syndrome. Any suspicion of Marfan stature should prompt a genetic work-up and evaluation of the aortic root. The Currarino-Silverman syndrome is associated with an abnormally short, U-shaped, unsegmented sternum and a high carinatum deformity. Individuals with the sporadic, genetic King syndrome have short stature, low-set ears, malar hypoplasia, micrognathia, kyphoscoliosis, cryptorchidism, slowly progressive myopathy with contractures, proptosis, and downslanted palpebral fissures. The singular event that leads to identification may be an episode of malignant hyperthermia, usually with a fatal outcome. To avoid this outcome, the syndrome must be identified preoperatively. Although many of the features of these syndromes are well known and, thus, intuitive, any abnormal facies or other worrisome features mandate genetic evaluation.
Classification and Descriptions of Deformities
Pectus carinatum deformities have been categorized by descriptive terms referring to the structures involved or classified as type I, II, or III. Two common descriptive categories are chondrogladiolar and chondromanubrial (Figs. 18-1 to 18-3). The chondrogladiolar type is more common and involves the inferior costal cartilages and the gladiolus. The sternum is protuberant and has parallel incurvings of the adjoining costal cartilages, which intensifies the appearance of the sternum. The chondromanubrial type affects the superior costal cartilages and the manubrium. Either type can be symmetric or asymmetric.
An adolescent male with an asymmetric chondrogladiolar pectus carinatum deformity.
A 16-year-old male with a chondrogladiolar pectus carinatum deformity (A) before and (B) after surgical repair.
Radiographs of a child with a chondromanubrial pectus carinatum deformity before and after surgical repair.
An alternative classification system refers to the defects as type I, II, or III. Type I, also known as keel chest, has a symmetric appearance. The maximal apex of the protrusion is inferior as described for chondrogladiolar. Type II is a symmetric chondromanubrial deformity also known as the Pouter deformity. Type III is an asymmetric or lateral protrusion, which can be associated with a depression on the opposite side.
While pectus carinatum patients do not complain of respiratory limitations as frequently as pectus excavatum patients do, functional limitations are sometimes found. There is some evidence of incomplete exhalation with pectus carinatum. This can lead to decreased stamina, exercise-induced wheezing, or shortness of breath. There is not strong evidence to support major cardiac or pulmonary abnormalities in these patients. Improvement in exercise stamina has sometimes been reported following surgical repair, but physiologic data are lacking.
More commonly, patients present complaining of pain. This can be due to pressures in the chest wall that develop from the cartilage overgrowth. The pain is often localized over the cartilage, and may be manifested as discomfort while lying on the sternum. Alternatively, patients may complain of neuropathic pain that is related to compression of intercostal nerves. This pain is often sharp and associated with rotational motion.
Psychological and social impacts of pectus carinatum can be quite significant. In the emotionally at-risk adolescent population, the impact of the physical appearance can manifest as poor self-image and self-esteem. This can contribute to anxiety and poor motivation, and ultimately alter peer relationships and performance in activities. The parental reaction to the deformity will often shape the child's attitude. A parent who draws great attention to the deformity can heighten the child's anxiety.
Diagnostic Evaluation and Indications for Intervention
Consideration of intervention for pectus carinatum first requires a thorough history and physical examination by a pediatric surgeon. Any suspicion of an underlying congenital or syndromic issue (particularly suspicion of Marfan syndrome) should prompt referral to a geneticist or cardiologist.
While radiographs are not required, they can be useful in quantifying the severity of the deformity. In patients with a chest wall deformity, a pelvimeter can be used to compare measurements of the sagittal thoracic diameters in a vertical position. The standard points of measurement are the upper manubrial margin (diameter T1), the sternal angle (diameter T2), and the costal arch intersection (diameter T3). The T1/T2 ratio is the most valuable index, by direct or radiographic measurement of the deformity. While this ratio is approximately 0.75 in a normal population, the ratio is lower—approximately 0.65—in children with pectus carinatum. A single-plane chest radiograph at the level of maximum deformity is sufficient to identify the internal bony landmarks for computerized tomography (CT) and also can be used to document correction.
Unlike pectus excavatum, pectus carinatum has no ratio value that serves as a threshold to indicate intervention may be necessary. Consideration of intervention is mainly based on the patient's symptoms and the degree to which the deformity interferes with activities. This is a very subjective decision-making process that requires the input of the surgeon, parent, and adolescent.
Ravitch first performed surgical repair of chondromanubrial deformities in 1946 and chondrogladiolar deformities in 1960. There have been many reports of alternatives and modifications since that time. The most common surgical procedure currently performed for pectus carinatum was named for Ravitch, although there are now several variations.
A transverse incision is made just below the nipple line. In females, this incision is curved downward bilaterally to fall in the projected inframammary crease. Skin flaps are raised from the angle of the manubrium to the xiphoid. The pectoralis muscles are then raised as flaps off the sternum and the costal cartilages out to the costochondral junctions. The rectus muscle is detatched from the sternum and the lower costal cartilages. Cartilage resection is then performed with preservation of the perichondrium (Fig. 18-4A to C). Electrocautery is used to score the perichondrium transversely with vertical crosshatches at either end. A periosteal elevator is used to separate the perichondrium from the cartilage circumferentially. The sternum is brought back into a flat position by reefing the perichondrium, performing an osteotomy, or both. An anterior transverse sternal osteotomy is very effective for correcting a symmetric chondrogladiolar deformity. In the case of asymmetric deformities with sternal twisting, an oblique wedge osteotomy can be performed (Fig. 18-4D). The pectoralis muscles and rectus muscles are reapproximated with absorbable suture. A drain is left in the bed of the flaps.
Exposure for open repair of pectus carinatum including subperichondrial cartilage excision. A. Electrocautery scores the perichondrium with a V-shaped incision delineating the medial aspect of the dissection. B. A freer elevator dissects subperichondrially to free the cartilage. C. Following resection of the second to seventh cartilages on each side. D. The sternal twist of the mixed deformity is corrected by a wedge osteotomy of the anterior sternal cortex with the widest aspect on the posterior depressed sternal border.
The length of each cartilage to be removed and the number of cartilage levels removed have been areas of variation and debate. Most authors recommend unilateral limited resection in only mild, focal deformities. Longer unilateral deformities often require bilateral cartilage resection to achieve a good result. More recently, there have been several reports of minimizing the extent of cartilage resection. In 2009, Fonkalsrud reported a 38-year experience of changing trends in surgical repair. Almost all of the last 303 patients, about one third of the total patients in the study, had only short segments of cartilage excised with suture reattachment. Similarly, there have been descriptions of both thoracoscopic and subpectoral cartilage resection using minimally invasive techniques. The thoracoscopic patients wore chest binders for 1 year after the surgery.
In 2009, Abramson described 5 years of experience with implantable stainless steel bars. This technique drew from the principles of the Nuss minimally invasive repair for pectus excavatum. This procedure was carried out on patients with malleable chest walls that could be manually compressed into a corrected position by the surgeon's hands. A subcutaneous bar (now modified to a submuscular bar) is tunneled over the area of maximal deformity, and fixation plates are attached to the ribs laterally. Manual pressure is applied over the chest wall to achieve correction, and then the bar and fixation plates are attached to one another. The short-term results have been good, without recurrences after the bar was removed. Long-term results and comparative data are not yet available.
Chondromanubrial deformities are approached through a high transverse incision. A wedge-shaped osteotomy is performed at the point of maximal protrusion. Closure of the osteotomy corrects both the posterior depression of the lower sternum and the anterior angulation of the manubrium. The second costal cartilage may also need to be removed to prevent buckling (Fig. 18-3).
Nonoperative therapy has mainly been applied to chondrogladiolar type deformities. Early descriptions in the 1970s reported that casting to remodel the chest wall achieved minimal success. The initiation of bracing in Brazil in the early 1990s was followed by several reports with more encouraging results using custom-fit orthotic bracing devices. This approach has gained increasing popularity over the past 2 decades.
Bracing is based on Wolff law stating that bone and surrounding tissue growth are influenced by external pressures placed on them. This is the same concept that Nuss and Abramson relied on and can also be applicable when the force is completely external to the patient. Pressure placed on the prominent area of the chest wall will theoretically remodel the growing tissues. The brace is prescribed for between 12 and 24 hours a day (Fig. 18-5A and B). The recent literature generally concludes bracing is effective. Many authors consider bracing to be most effective at younger ages (around 12 years old), and less effective when the chest wall is less malleable (16 years and older). Major limitations of bracing often involve patient compliance and patient education is necessary for optimal compliance. Many centers are using bracing as first-line therapy and then using surgery in the case of brace failures.
Pectus carinatum orthotic compression brace. A. Oblique view of the patient wearing the brace with anterior compression plate visible. B. Posterior compression plate view of the brace.