A cleft sternum is a rare congenital chest wall defect in which the breastbone fails to fuse along the midline during fetal development, leaving a gap that can range from a small notch at the top of the chest to a complete split running the full length of the bone. Because the sternum normally acts as a shield over the heart and great vessels, the gap can leave those structures worryingly close to the surface. Most cases are spotted at birth when the skin over the defect visibly pulses with each heartbeat, though prenatal ultrasound sometimes catches it earlier. The condition is treatable, often with a single operation, but the details depend heavily on the type of cleft, the child’s age, and whether the heart or other organs are also affected.
How the Sternum Normally Forms and What Goes Wrong
During early embryonic life, two bars of cartilage grow inward from either side of the developing chest and meet at the midline, where they gradually fuse into a single breastbone. That fusion normally begins near the top and progresses downward. A cleft sternum results when this migration or fusion stalls partway through, or never happens at all. The process is guided by signaling molecules in the surrounding tissue; animal studies have shown that disrupting certain molecular pathways in the ventral body wall mesenchyme prevents the sternal halves from coming together and can even cause the heart to protrude through the gap.1PubMed Central. Mesenchymal Wnt signaling promotes formation of sternum and thoracic body wall In humans, the exact genetic trigger varies from case to case and is often unknown, though several named syndromes have been linked to sternal clefting.
Types of Sternal Cleft
Sternal clefts are classified by where the gap sits along the breastbone. The three main types are superior (the gap is at the top), inferior (the gap is at the bottom), and complete (the entire sternum is split).2American Journal of Medical Genetics. Sternal cleft: Case report and review of a series of nine patients The superior partial cleft is by far the most common, accounting for roughly two-thirds of reported cases.3PubMed Central. Phenotypic spectrum and management of sternal cleft: literature review and presentation of a new series This makes anatomical sense: because fusion normally starts at the top and works downward, a process that stalls early leaves a gap in the upper sternum while the lower portion may still manage to close. An inferior cleft, by contrast, tends to carry more serious associations because the lower sternum sits near the diaphragm, pericardium, and abdominal wall, all of which can be involved in more complex malformation syndromes.
Complete clefts, where the two halves of the sternum never meet at all, are the rarest form. In these cases the entire front of the chest lacks its usual bony protection, and the visible cardiac pulsation beneath the skin can be dramatic. Even so, some children with complete clefts have surprisingly few symptoms early in life, which can sometimes delay referral for surgery.
What It Looks and Feels Like
The hallmark sign visible right after birth is paradoxical chest wall movement: the soft area over the cleft sinks inward when the baby breathes in and bulges outward when the baby breathes out, the opposite of what a rigid breastbone would do.4PubMed Central. Isolated V-Shaped Sternal Cleft – A Rare Chest Wall Malformation In many newborns, you can also see and feel the heartbeat pulsing directly beneath the skin of the upper chest.5Annals of Pediatric Surgery. Primary closure of superior partial sternal cleft in a 2-month-old girl: case report Parents understandably find this alarming, even when the baby is otherwise feeding and growing well.
Despite the visible pulsation, roughly three-quarters of sternal cleft patients are described as asymptomatic at initial presentation.6PubMed Central. Phenotypic spectrum and management of sternal cleft: literature review and presentation of a new series That does not mean the defect is harmless. The paradoxical breathing pattern can become a problem over time, contributing to repeated respiratory infections, and the unprotected heart and mediastinum remain vulnerable to direct trauma.7Journal of Pediatric Surgery Case Reports. Surgical treatment of a sternal cleft associated with pectus excavatum Surgery is recommended even in many asymptomatic children for these reasons, along with cosmetic concerns that tend to grow as the child does.
Conditions That Travel With Sternal Clefts
A sternal cleft rarely arrives alone. Literature reviews have found that about seven out of ten patients have at least one other congenital defect.8PubMed Central. Phenotypic spectrum and management of sternal cleft: literature review and presentation of a new series The most common companions are cardiovascular malformations.9PubMed Central. Upper Sternal Cleft Associated With Congenital Cardiac Defect: Single Stage Surgical Correction These can range from a persistent left-sided superior vena cava, a vein that normally disappears before birth, to more complex structural heart disease.10Case Reports in Pediatrics. Congenital Sternal Cleft along with Persistent Left-Sided Superior Vena Cava: A Rare Presentation
Two named syndromes deserve special mention because they account for a disproportionate share of sternal cleft cases:
- PHACES syndrome: This acronym stands for posterior fossa malformations, hemangiomas, arterial anomalies, cardiac defects and coarctation of the aorta, eye abnormalities, and sternal defects. Children with PHACES typically have a large facial hemangioma (a benign vascular birthmark) along with one or more of the other features. Sternal clefting is part of the recognized spectrum, and studies investigating children with segmental facial hemangiomas have found PHACES in a meaningful fraction of those also carrying a sternal cleft.11PubMed. Sternal cleft and segmental facial hemangiomas in children with phaces syndrome: effectiveness and safety of conservative management and surgical correction12The Journal of Dermatology. PHACES syndrome presenting as hemangiomas, sternal clefting and congenital ulcerations on the helices
- Pentalogy of Cantrell: This more severe combination involves five features: an inferior sternal cleft, a defect in the front of the diaphragm, absence of the lower pericardium, a midline abdominal wall defect, and a congenital heart malformation. When the heart herniates through the gap in the lower chest wall, the condition is called ectopia cordis. Surgeons have described repairing these inferior clefts with techniques including bilateral sternal bar turnover flaps and titanium plates to reconstruct the missing bone.13PubMed Central. Repair of inferior sternal cleft using bilateral sternal bar turnover flaps in a patient with pentalogy of cantrell14Research Square. Technique Using a Titanium Plate to Reconstruct the Inferior Sternal Cleft in Pentalogy of Cantrell: Lessons From Four Patients
Because of the high rate of associated defects, any baby diagnosed with a sternal cleft gets a thorough workup looking for cardiac, vascular, and abdominal abnormalities before a surgical plan is made.
Detecting a Sternal Cleft Before and After Birth
Prenatal detection is possible but not routine. In at least one documented case, a complete sternal cleft was identified on ultrasound at 22 weeks of gestation; the clue was a thinned, depressed midline chest wall that transmitted the cardiac pulsation visibly on the scan.15Ultrasound in Obstetrics & Gynecology. Prenatal ultrasonography and neonatal imaging of complete cleft sternum: a case report When an abnormality is suspected on ultrasound, fetal MRI can add detail and help distinguish a sternal cleft from other midline defects.16PubMed. Sternal cleft: prenatal multimodality imaging Prenatal diagnosis allows parents and the medical team to plan the delivery at a center with pediatric surgery capability, which matters if the baby will need early intervention.
After birth, the diagnosis is usually obvious from the visible paradoxical chest movement and palpable cardiac pulsation. Imaging is still needed to map the defect precisely and to look for associated anomalies. CT with three-dimensional reconstruction shows the exact extent and shape of the bony gap, while MRI can reveal whether any cartilage has developed in the cleft space and how mature it is. Echocardiography checks for congenital heart defects, and brain MRI may be added if PHACES syndrome is suspected.17American Journal of Case Reports. Congenital Superior Sternal Cleft Isolated in a Newborn: Report of a Rare Case and a Literature Review18PubMed Central. Reconstruction of Congenital Sternal Clefts: Surgical Experience and Literature Review
Why Timing Matters for Surgery
The single most important factor in choosing a surgical approach is the child’s age, and there is a strong consensus that earlier is better. In a newborn, the cartilaginous chest wall is still soft and flexible. The two sternal halves can often be gently brought together and sutured directly at the midline without any additional material, a procedure called primary closure. This straightforward approach accounts for most repairs in the literature and is the preferred method when it is feasible.19PubMed Central. Phenotypic spectrum and management of sternal cleft: literature review and presentation of a new series
As the child grows, the thoracic cage stiffens and the sternal bars become harder to mobilize. By a few months of age, pulling the two halves together may compress the heart and great vessels enough to cause dangerous drops in blood pressure or cardiac output. Surgeons recognize this as the key limitation of primary closure in older infants and children. When direct approximation is not safe, the gap must be bridged with some form of interposition material. Reported options include autologous cartilage grafts harvested from the child’s own ribs, bovine pericardium patches, prosthetic mesh, and even titanium plates in the most complex reconstructions.20Asian Cardiovascular and Thoracic Annals. Reconstruction of sternal cleft with autologous cartilage graft in an adult21PubMed Central. Sternal cleft: new options for reconstruction In older patients whose chests are no longer flexible, a bovine pericardium patch can allow closure while avoiding more invasive procedures or permanent non-absorbable implants.22PubMed Central. Sternal cleft: new options for reconstruction
A combined approach is sometimes used for intermediate-age patients: surgeons create a posterior periosteal flap from the back surface of the sternal bars, perform a sliding chondrotomy to allow the bars to move toward each other, and fill any remaining gap with a cartilage graft.23PubMed Central. Surgical repair of a sternal cleft malformation When a sternal cleft coexists with a congenital heart defect, some surgical teams perform a single-stage operation that corrects both the cardiac lesion and the chest wall in one sitting.24PubMed Central. Upper Sternal Cleft Associated With Congenital Cardiac Defect: Single Stage Surgical Correction
What to Expect After Repair
Outcomes for sternal cleft repair are generally excellent when the defect is addressed in infancy. In a single-center series spanning a decade, no deaths occurred and no patient required a second operation over a median follow-up of more than five years. CT scans confirmed successful closure and progressive bony fusion in every case, and no child went on to develop pectus excavatum.25PubMed Central. Primary repair of sternal cleft: a ten-year single-center experience Parents reported high cosmetic satisfaction despite minor contour irregularities. About a quarter of patients had mild sternal depression, one had mild protrusion, and all had visible scars, but none reported psychological effects related to chest wall appearance, and none had cardiopulmonary symptoms at long-term follow-up.26PubMed Central. Primary repair of sternal cleft: a ten-year single-center experience
Shorter-term data from other institutions are consistent. A four-patient case series reported that each child spent one night in intensive care, was discharged home within three to five days, and had no known long-term negative outcomes.27Journal of Pediatric Surgery Case Reports. Sternal cleft repair: A single-institution case-series A separate 27-year series using a periosteal-flap-and-cartilage-graft technique reported no postoperative deaths, no major complications, and a mean hospital stay of six days.28European Journal of Cardio-Thoracic Surgery. Twenty seven-year experience with sternal cleft repair The most commonly noted minor complication across studies is subcutaneous fluid collection that prolongs drainage but resolves without further surgery. One institution reported a single case of pneumothorax that required needle decompression in the operating room but did not lead to lasting problems.29Journal of Pediatric Surgery Case Reports. Sternal cleft repair: A single-institution case-series
Adults Who Were Never Treated
Occasionally a sternal cleft goes unrepaired into adulthood, either because it was never diagnosed or because it was mild enough that no one pursued surgery. These patients sometimes present later in life with cosmetic concerns, exercise intolerance, or anxiety about the visible cardiac pulsation in their chest. Surgery in an adult is more complex because the chest wall has fully ossified and cannot simply be pushed together. Reconstruction typically requires autologous cartilage grafts or prosthetic materials to bridge the gap. One report described a 23-year-old woman with a partial superior cleft who underwent reconstruction with costal cartilage grafts and achieved a good result.30Asian Cardiovascular and Thoracic Annals. Reconstruction of sternal cleft with autologous cartilage graft in an adult Adult repair is feasible, but the surgical options are narrower and the recovery potentially longer than in infancy, which is the main argument for early intervention.
Sex Distribution and How Common Sternal Clefts Are
Sternal clefts are rare enough that no large population-based prevalence study exists. Most of what is known comes from case reports and case series compiled in literature reviews. One review pooling data from 51 published series found 86 patients, about 62 percent of whom were female.31PubMed Central. Phenotypic spectrum and management of sternal cleft: literature review and presentation of a new series Whether this female preponderance reflects a genuine sex-linked susceptibility or a referral and reporting bias is not clear. The rarity of the condition makes it difficult to study in the kind of large cohort that would settle the question.
The condition has also surfaced in a paleopathological context. A superior sternal cleft was identified in the skeletal remains of a middle-aged woman excavated from a 19th-century Dutch psychiatric asylum cemetery. The finding, combined with other skeletal anomalies, prompted the researchers to consider several possible underlying syndromes, including Coffin-Lowry syndrome and PHACES syndrome, as the most likely explanations.32PubMed Central. A review of the embryological development and associated developmental abnormalities of the sternum in the light of a rare palaeopathological case of sternal clefting The case is a reminder that sternal clefts are not a modern discovery; they have occurred throughout human history, and presumably many went unrecognized or untreated.
Anesthesia and Perioperative Considerations
Operating on a newborn or infant with a sternal cleft brings particular anesthetic challenges. The heart lies close to the skin surface, meaning external chest compressions during resuscitation would not work the same way they do when a normal sternum is present. Positioning the child on the operating table must avoid direct pressure on the unprotected mediastinum. Ventilation strategy also matters: because the chest wall moves paradoxically, positive-pressure ventilation through an endotracheal tube can behave somewhat differently than in a baby with an intact sternum. Review articles on sternal malformations have emphasized the need for careful perioperative planning and monitoring specific to these anatomical realities.33Pediatric Anesthesia. Sternal malformations and anesthetic management Most centers manage these cases in a pediatric cardiac surgical environment where specialized anesthesiologists and neonatal intensivists are on hand.
Postoperatively, the child is typically monitored in an intensive care unit overnight while the surgical team watches for hemodynamic instability or respiratory compromise as the newly closed chest wall adjusts. As noted earlier, hospital stays in reported series have ranged from three to six days, and serious postoperative complications are uncommon. The fact that most children leave the hospital within a week speaks to how well-tolerated these repairs tend to be when performed at experienced centers.