INTRODUCTION — Pectus carinatum is an uncommon deformity of the chest wall that presents during childhood and usually worsens during adolescence. Most patients have no associated symptoms, and repair usually is for cosmetic indications.
The definition, clinical features, and management of pectus carinatum will be presented here. Pectus excavatum, the most common chest wall deformity characterized by depression of the sternum, is discussed separately. (See "Pectus excavatum: Etiology and evaluation" and "Pectus excavatum: Treatment".)
TERMINOLOGY — Pectus carinatum is a protrusion deformity of the anterior chest wall. The term is derived from the Latin phrase for "chest with keel." Other terms for the deformity include chicken breast, pigeon chest, pyramidal chest, thorax cuneiform, or sternal kyphosis. There are two main types of pectus carinatum deformity [1-3]: chondrogladiolar prominence and chondromanubrial prominence (figure 1). Some patients have a "lateral" (asymmetric) deformity or combination of chondrogladiolar and chondromanubrial types.
Chondrogladiolar prominence — Chondrogladiolar prominence, also known as chicken breast or keel chest, is the most common type of deformity [3,4]. The middle and lower portions of the sternum protrude and arch forward. The costal cartilages are concave and usually symmetrically depressed, accentuating the sternal prominence. The deformity is asymmetric in 30 to 50 percent of cases [4,5]. Infrequently, patients can have a combined pectus carinatum on one side of the chest and pectus excavatum on the other .
Chondromanubrial prominence — Chondromanubrial prominence, also known as Pouter pigeon breast, is a more complex and substantially less common form of pectus carinatum deformity, representing approximately 5 percent of cases [6,7]. In this form, the upper portion of the sternum protrudes anteriorly and the body of the sternum is deviated posteriorly. A final anterior deflection of the distal sternum gives the characteristic Z shape to the sternum on a lateral view.
PREVALENCE — Pectus carinatum is an uncommon deformity that occurs in approximately 1 per 1500 live births [3,8]. It is four times more common in males than females. There is a strong familial association, with up to 25 percent of affected patients reporting chest wall abnormalities in family members [3,5].
Most reports suggest that pectus carinatum is fivefold less common than pectus excavatum [6,8]. Pectus carinatum appears to be more common in White and Hispanic populations .
Pectus carinatum that is not clinically obvious can be an incidental finding on imaging of the chest performed for other reasons. In one series, subclinical pectus carinatum deformity was noted on 2 percent of computed tomography (CT) scans of the chest .
ETIOLOGY — The cause of pectus carinatum is unknown. Proposed mechanisms include abnormal costal cartilage growth [4,10] and abnormal growth of the sternum or ribs [11-13]. Pectus carinatum also occurs in association with a variety of genetic syndromes and disorders, many of which affect connective tissue [14,15]. (See 'Associated abnormalities' below.)
Natural history — In more than 90 percent of patients, pectus carinatum deformity is diagnosed after the patient's 11th birthday. The defect often worsens dramatically during the adolescent growth spurt . Fewer than 10 percent will have a severe defect by three years of age. Spontaneous improvement of pectus carinatum does not occur. Most patients with untreated isolated pectus carinatum deformity have no associated morbidity or mortality [5,16].
Symptoms — For many patients evaluated for pectus carinatum, cosmetic appearance is the primary concern and there are few physiologic complaints [17-19]. By contrast, in one series of 260 patients who underwent surgical correction of pectus carinatum, the majority of patients had subjective complaints of exertional dyspnea, exercise limitation, frequent respiratory infections, or asthma . These symptoms improved in almost all patients after surgical repair based on subjective reporting by the patients. After operative repair, the mean improvement in vital capacity as measured by incentive spirometry was 12.5 percent in a subset of 105 patients. However, the preoperative baseline vital capacity as a percent of predicted was not reported. In most other series, objective abnormalities are usually subtle or lacking [16-19]. (See 'Additional testing' below.)
The pectus carinatum body image quality-of-life (PeCBI-QOL) questionnaire is a validated instrument that can be used to objectively assess psychological issues related to pectus carinatum .
Associated abnormalities — Associated musculoskeletal abnormalities are frequent, occurring in 22 percent of patients in one series . Spinal anomalies or scoliosis are most common, occurring in 15 to 30 percent of affected patients [4,21,22]. (See "Adolescent idiopathic scoliosis: Clinical features, evaluation, and diagnosis".)
Pectus carinatum may be associated with several disorders or syndromes :
●Marfan syndrome (see "Genetics, clinical features, and diagnosis of Marfan syndrome and related disorders")
●Noonan syndrome (see "Noonan syndrome")
●Poland syndrome (see "Chest wall diseases and restrictive physiology", section on 'Poland syndrome')
●Osteogenesis imperfecta (see "Osteogenesis imperfecta: An overview")
●Morquio syndrome (see "Mucopolysaccharidoses: Clinical features and diagnosis", section on 'MPS type IV (Morquio syndrome)')
EVALUATION — The evaluation of pectus carinatum includes documentation of the severity of the defect by physical examination. Imaging is reserved for patients who will be managed surgically, as part of a preoperative evaluation.
Physical examination — On physical examination, the anteroposterior diameter of the chest is increased and chest wall motion is often less than normal . Occasionally, there is tenderness on palpation of the anterior chest wall over the deformity.
The examination should document these features :
●Type of deformity (chondrogladiolar or chondromanubrial, or mixed carinatum/excavatum) and degree of asymmetry. (See 'Terminology' above.)
●Whether the defect can be corrected using pressure on the sternum. Irrespective of the severity of the defect, the ability to correct the defect, at least partially, with manual pressure has an impact on the options for correction .
●Presence or absence of scoliosis or other associated abnormalities (eg, Marfan, Noonan, Poland, Coffin-Lowry, or Morquio syndromes or osteogenesis imperfecta). (See 'Associated abnormalities' above and "Adolescent idiopathic scoliosis: Clinical features, evaluation, and diagnosis".)
Photography — Photographs are helpful for objective documentation and comparison with previous examinations. They are particularly helpful in young patients with evolving deformities as well as in patients undergoing surgery or bracing to measure outcomes after treatment. Special photographic techniques illustrate body wall topography more precisely than plain photography but are not widely available [5,25,26].
Chest imaging — The evaluation of a patient with pectus carinatum typically includes chest radiographs to document the severity of the deformity and to detect scoliosis and monitor its progression.
We use CT for preoperative planning (image 1). We do not routinely perform CT on patients who will not be having surgery.
CT parameters that are useful for measuring severity include:
●Sternal protrusion – The angle at the point of greatest sternal rotation .
●Pectus severity index (PSI) – The PSI, also known as the Haller index, is defined as the width of the chest divided by the distance between the sternum and spine. The normal value is 2.54 . In patients with pectus carinatum, a lower PSI indicates a more severe deformity (in contrast with patients with excavatum, in which a higher PSI indicates a more severe deformity). In one group of 260 subjects with pectus carinatum, the mean PSI was 1.81 (range 1.19 to 2.10) .
●Asymmetry index – The ratio of anteroposterior diameter of the left to right thorax and the angle of sternal rotation .
In patients with focal protrusion of one or more costal cartilages, sonographic imaging can be helpful in differentiating a malformed cartilage from a neoplastic rib mass.
Additional testing — In general, no additional routine testing is needed to evaluate patients with pectus carinatum and a thorough history and physical examination are sufficient to determine if any additional testing is necessary. Tests are usually limited to investigation of associated disorders (eg, scoliosis), symptoms (eg, dyspnea), or possible syndromes (eg, Marfan, Noonan, Poland, Coffin-Lowry, or Morquio syndromes or osteogenesis imperfecta). (See 'Associated abnormalities' above and "Adolescent idiopathic scoliosis: Clinical features, evaluation, and diagnosis".)
When cardiorespiratory function is measured in patients with pectus carinatum, results are usually normal and do not change after surgical repair [30,31]. In rare cases associated with severe scoliosis, restrictive lung disease can occur .
Screening echocardiograms have been suggested, based on a case series of patients with pectus carinatum in which 3.2 percent (5/155) had mitral valve prolapse and 7.1 percent (11/155) had aortic root dilation (among whom five had Marfan syndrome) . Neither of these findings were associated with the reported cardiac symptoms (chest pain and palpitations). Because most of the positive echocardiographic findings are likely related to associated disorders, such as Marfan syndrome, most institutions do not perform routine echocardiography in patients with pectus carinatum unless there are symptoms or signs suggesting one of these other disorders. However, it should be recognized that some of the cardiac abnormalities were found in patients without recognized syndromes.
Timing of referral — We suggest referral to a pediatric surgeon as soon as pectus carinatum becomes apparent. The timing of bracing or surgical intervention depends on the age of the child and the severity and progression of the deformity.
●For the minority of patients who present before puberty, the surgeon provides education, reassurance, and monitoring. Children presenting between 5 and 10 years of age can be good candidates for bracing because their chest wall is compliant; however, they often lack the emotional maturity to complete a six- to eight-month bracing protocol. It is reasonable to delay treatment in this age group until early in the pubertal growth spurt, when adherence to the bracing regimen is likely to be better.
●For the majority of patients who present during the pubertal growth spurt, the surgeon can offer bracing or surgical repair, depending on the patient's characteristics and preferences.
Whether to treat — Pectus carinatum is primarily a cosmetic rather than a functional concern. The decision of whether to treat depends on the severity of the defect (anterior chest protrusion, sternal angulation, and asymmetry) and the patient and family's level of concern. Thus, the indications for treatment cannot be captured in an objective measure.
In this topic review, we define a "mild" deformity as one for which most patients would not choose to have active treatment (surgery or bracing), a "moderate" deformity as a distinct deformity for which many patients would choose to have treatment, and a "severe" deformity as a substantial cosmetic problem for which most patients would choose to have treatment.
Choice of therapy — Both bracing and surgery provide safe and effective treatment. Bracing is a relatively new approach to treatment of pectus carinatum that has rapidly gained public acceptance. The optimal indications for bracing and relative advantages and disadvantages compared with surgical approaches are not established. In our practice, we generally take the following approach, recognizing that it is based on limited data:
●Candidates for bracing – We offer bracing to patients with mild or moderate pectus carinatum. During the evaluation for bracing, it is critically important to evaluate the flexibility of the chest because bracing is more difficult and less effective in patients with skeletally mature, stiffer chest walls . For patients with compliant defects that can be reduced with pressure on the chest, sternal manipulation and bracing can be used at a substantially lower pressure compared with unreducible defects .
●Candidates for surgery – Surgery is more likely to be effective than bracing for patients with:
•Severe pectus carinatum
•Unwilling or unable to adhere to a rigorous bracing schedule
•Inflexible chest walls (eg, patients in late puberty or older)
•Moderate or severe sternal asymmetry 
Surgical intervention is also an acceptable approach for patients with milder degrees of pectus carinatum, based on patient and clinician preference.
Bracing — In patients with a flexible chest wall, the deformity may be improved by bracing. A flexible defect is one that can be manually corrected by moderate compression on the initial physical examination . The advantage of bracing is the decreased morbidity and improved cosmesis of a nonsurgical approach, as well as substantial cost savings as compared with surgical correction .
Protocols — A variety of bracing protocols have been described.
●Compressive brace – In general, patients with more flexible chest walls will require less pressure to correct the deformity and can be corrected with a shorter interval of time. Patients with stiffer chest walls will require a higher pressure of correction, a progressive increase in pressure over time, and a longer treatment duration. The therapeutic pressure is measured with a transducer when fitting the brace and at subsequent monthly adjustments.
Traditionally, patients were asked to wear a brace with high pressures nearly continuously (up to 20 hours daily) until skeletal maturation was complete [33,34]. Outcomes were generally good for patients who adhered to the protocol, but up to 50 percent of patients did not adhere to or did not complete the protocol. Subsequently, less rigorous protocols have been used and found that bracing for 8 to 12 hours/day had similar or better success rates (85 percent) and time to correction (7.3 months), with better protocol adherence (90 percent) .
●Manipulation and bracing – A novel approach involves initial correction of the deformity through manual manipulation, enhanced by topical anesthesia and infrared massage, followed by bracing. This approach appears to have substantially better rates of patient satisfaction and adherence to the protocol. In a large case series of patients with a flexible deformity, the chest wall was first manipulated ("soft-tissue release") in a single session until the deformity could be flattened by sustained pressure [24,36]. Then, a brace was fitted with just enough pressure to maintain the correction, described as "compressive bracing without significant progressive tightening." The duration of bracing varied with the flexibility and severity of the deformity and averaged 32 weeks for active noncompressive bracing, with an additional eight weeks for maintenance. With this protocol, the adherence to the bracing protocol was high (98 percent during the first 12 weeks) and almost all patients completed the bracing protocol . Only 14 percent of the initial cohort had stiff deformities that required compressive bracing with progressive tightening.
●Bracing with physiotherapy – One small randomized trial of 23 patients found that chest bracing combined with a customized physiotherapy protocol to strengthen the thoracic muscles was more successful than bracing alone in improving the pectus defect .
Outcomes — Several case series report that bracing leads to improvement or resolution of the pectus deformity in at least 75 to 90 percent of patients who comply with the protocol [6,33,34,38]. Bracing protocols can be challenging to complete, but among those patients who do, there is a high success rate. Adherence to the protocol may be determined in part by early success in remolding the pectus deformity. In one large series, the patients who were compliant with bracing all had noticeable improvement in the pectus deformity within the first month of bracing, while those who did not complete the bracing protocol did not see any early improvement . Successful bracing also appears to be associated with earlier pubertal status or age at the start of bracing [34,40,41], more flexible deformity , and less severe or asymmetric deformities [29,40].
Specific prognostic features are illustrated by the following studies:
●Adherence to the bracing protocol – A prospective series described treatment with a self-adjustable bracing system used nearly continuously for a correction phase, then only at night for a maintenance phase . Approximately 55 percent of the cohort adhered to the bracing protocol, and these patients reported clinically significant satisfaction with their physical appearance (rising from 2.9 to 4.3 on a 5-point scale). Those who had not reached Tanner stage IV required 4.2±0.9 months to reach full correction, while those who started bracing after reaching Tanner stage IV needed 8.0±7.1 months of bracing to get a full correction. Among this group of adherent patients, only 2 percent did not achieve improvement. The remaining 45 percent of the patients entering the protocol were deemed treatment failures, most of these due either to loss to follow-up or to marked nonadherence to the protocol. The authors suggest that the use of a brace in which the patient can adjust the compression pressure is associated with a higher rate of treatment adherence and with greater overall success.
●Flexibility of the deformity – A series of 209 patients described treatment with a customized brace with a dynamic compressor system, which was adjusted to reflect the compression force needed to correct the deformity and also allowed lateral expansion of the chest . The length of treatment and cosmetic outcome were closely associated with the initial pressure needed to correct the deformity (ie, the stiffness of the carinatum defect). Patients requiring pressures lower than 2.5 pounds per square inch to correct the deformity at the initial assessment completed treatment rapidly (in an average of five months) and had good cosmetic outcomes, based on a subjective assessment by clinician and family. Patients requiring compression force higher than 5 pounds per square inch required a longer period of bracing (averaging 12 months treatment) and were less likely to have good cosmetic outcomes.
●Complexity of the deformity – In a small case series, four patients who failed bracing despite compliance had a significantly higher pectus severity index (PSI) and asymmetry index and greater angle of sternal rotation compared with 24 patients for whom bracing was successful . This suggests that patients with complex pectus carinatum defects may not be good candidates for bracing, though more research needs to be done to clarify this.
Complications of bracing are minimal. There are some reported problems with mild skin erythema, but skin breakdown is rare [6,33,34,41,42].
Indications — Surgery is the usual treatment for patients with pectus carinatum who have severe defects, whose chests are not flexible, or who have moderate to severe sternal asymmetry and is an option for those with moderate defects. Surgery is also used when bracing has not been effective, either due to poor compliance with the bracing protocol or poor patient selection. The techniques used are similar to those used to repair pectus excavatum deformities. (See "Pectus excavatum: Treatment".)
●Modified Ravitch procedure – The typical surgical technique, known as a modified Ravitch repair, usually includes [4,17,43,44]:
•Resection or reshaping segments of all of the abnormal costal cartilage, preserving the perichondrium from which new cartilage grows
•Reshaping and repositioning the sternum
•Inserting a removable or absorbable strut (figure 2) or synthetic mesh "hammock" underneath the mobilized sternum 
•More severe deformities require a more extensive procedure 
Postoperative morbidity is approximately 4 to 11 percent [43,46]. In a series of 90 patients, complications included wound seroma in five, pleural effusion in three, and pneumothorax in two patients . Mortality is low in the absence of associated anomalies.
Two groups have adapted the technique for pectus carinatum repair to a thoracoscopic approach, but the procedure is limited to unilateral repair or one side at a time [47,48]. In one of these reports, a supporting strut was kept in place for 20 months and, at the time of the report, 21 of 37 struts had been removed with no recurrence . All of the patients assessed the surgical outcome as either excellent or good.
●Minimally invasive pectus carinatum repair – A minimally invasive technique that employs an extrapleural support bar (sometimes termed the Abramson method) has been used in selected patients with pectus carinatum [3,49,50]. The patients in these series had chondrogladiolar pectus carinatum (either symmetric or asymmetric), and their chest walls were flexible enough that the defects could be manually corrected by moderate compression on the initial physical examination. In the largest case series, the bar was removed between two and three years after insertion and more than 90 percent reported excellent results . In a separate review of 184 patients, 99.5 percent were satisfied with the appearance after initial repair and 91 percent remained satisfied after bar removal . Complications included pneumothorax (7 percent), wound infection (10 percent), and wire breakdown of the stabilizer (5 percent); overcorrection causing pectus excavatum developed in 6 percent.
Timing of surgery — Opinions vary regarding the optimal age for surgery. In general, we perform surgical repair toward the end of the pubertal growth spurt, typically around 13 to 16 years of age . This timing takes advantage of the ease of remolding an immature chest wall, while minimizing the time that the defect can recur with future growth. Good to excellent surgical results have also been achieved in adult patients . Repair in prepubertal children may be associated with development of asphyxiating chondrodystrophy if extensive resection of the costal cartilages is performed [52,53]. Repair in patients with Marfan syndrome is usually delayed until skeletal maturity is attained because recurrence is more likely with earlier repair.
Outcomes — Cosmetic outcomes after surgery, reported using subjective criteria, are good to excellent in more than 90 percent of patients [43,44,54,55]. Recurrence is uncommon , and, when it does occur, it is most often in patients who had surgical correction before their growth spurt .
Continued surveillance should be maintained for scoliosis. It is not known if correction of the deformity affects the incidence of scoliosis .
SUMMARY AND RECOMMENDATIONS
●Definition – Pectus carinatum is an uncommon deformity of the chest wall characterized by protrusion of the sternum. In the majority of cases, the middle and lower portions of the sternum protrude (known as chondrogladiolar prominence) and the defect is symmetrical (figure 1). (See 'Terminology' above.)
●Clinical features – In more than 90 percent of patients, pectus carinatum deformity is first noted during early adolescence, and it often worsens dramatically during the adolescent growth spurt. The defect does not resolve spontaneously. The vast majority of patients have no physiologic symptoms, and cosmetic appearance is the primary concern. (See 'Clinical features' above.)
A minority of patients with pectus carinatum have associated spinal abnormalities such as scoliosis. It is more common in patients with Marfan and Noonan syndromes, as well as a few other syndromes. (See 'Associated abnormalities' above.)
●Imaging – The evaluation of a patient with pectus carinatum should include chest radiographs to document the severity of the deformity and to detect scoliosis and monitor its progression. We reserve the use of CT to evaluate patients who are being prepared for surgical repair (image 1). (See 'Chest imaging' above.)
●Treatment – Pectus carinatum is primarily a cosmetic concern. The decision of whether to treat depends on the severity of the defect and the patient's and family's level of concern. Both bracing and surgery provide safe and effective treatment. (See 'Treatment' above.)
•Bracing – We suggest bracing as the initial approach for patients with mild to moderate pectus carinatum defects (Grade 2C). Success is more likely in patients who have flexible chest walls and in those who are willing to adhere closely to the bracing regimen. Newer, less stringent bracing protocols with lower bracing pressures seem to result in better patient adherence with at least as good outcomes. (See 'Bracing' above.)
•Surgery – We suggest surgery as the initial approach for patients with severe pectus carinatum and for those who are skeletally mature (Grade 2C). Bracing is less likely to be successful for these groups of patients compared with those with mild or moderate pectus carinatum and/or a flexible deformity. Surgery is also an appropriate approach for patients with less severe pectus carinatum who are unwilling to adhere to bracing regimens, provided that they have entered their pubertal growth spurt. Surgery should only be performed after patients have entered their pubertal growth spurt. This is because of the small but definite risk of asphyxiating thoracic dystrophy in younger patients who undergo a modified Ravitch pectus carinatum repair. (See 'Surgery' above.)
2 : Morphologic findings of chest deformities in children corresponding to the Willital-Hümmer classification.
11 : Growth disturbance of the sternum and pectus deformities: imaging studies and clinical correlation.
12 : The relation of pectus excavatum to pectus carinatum; olassification of anterior chest wall deformities and the effect on treatment.
13 : The etiology of pectus carinatum involves overgrowth of costal cartilage and undergrowth of ribs.
18 : Surgical treatment of protrusion deformities of the sternum and costal cartilages (pectus carinatum, pigeon breast).
19 : Pigeon breast (pectus carinatum) and other protrusion deformities of the chest of developmental origin.
20 : Development and validation of the Pectus Carinatum Body Image Quality of Life (PeCBI-QOL) questionnaire.
24 : External Compressive Bracing With Initial Reduction of Pectus Carinatum: Compliance Is the Key.
27 : Compressive orthotics in the treatment of asymmetric pectus carinatum: a preliminary report with an objective radiographic marker.
29 : Compressive orthotic bracing in the treatment of pectus carinatum: the use of radiographic markers to predict success.
30 : A summary of preoperative and postoperative cardiorespiratory performance in patients undergoing pectus excavatum and carinatum repair.
31 : The effect on cardiopulmonary function after thoracoplasty in pectus carinatum: a systematic literature review.
36 : Initial reduction of flexible pectus carinatum with outpatient manipulation as an adjunct to external compressive bracing: technique and early outcomes at 12 weeks.
37 : Does physiotherapy applied in conjunction with compression brace treatment in patients with pectus carinatum have efficacy? A preliminary randomized-controlled study.
46 : A 20-year review of pectus surgery: an analysis of factors predictive of recurrence and outcomes.
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