The actual cause of pectus carinatum is still unknown. This condition can run in families, and genetics may be a risk factor.
People with particular inborn conditions are likelier to develop an asymmetrical pigeon chest.
This article will cover everything you need to know about the two most common types of pectus carinatum deformity.
Horizontal Symmetry Classifications
Doctors divide pectus carinatum into three smaller groups and types, depending on where the bulge is horizontal:
- Symmetric (classical)
- Asymmetric (asymmetric)
If the pectus carinatum is asymmetrical, there is often a compensatory flattening or depression of the rib cage. That flattening of the rib cage can be on both sides of the deformity is symmetrical.
A computed tomography scan of the chest in cases with lateral pectus carinatum indicates that the sternum is at an oblique angle to the body’s central line. That’s important when preparing for surgery.
Poor Posture May Cause Asymmetry
Patients with pectus carinatum, like those with pectus excavatum, generally have poor posture and spinal difficulties. These are additional reasons for asymmetric chests to appear.
Those with a particular asymmetrical expression of the chest bone may experience difficulties breathing. Still, in the great majority of instances, the pigeon chest is only an aesthetic issue.
During the development period of the deformity, daily wear of a tight-fitting bandage or orthosis might permanently help repair an asymmetrical pectus carinatum deformity.
The pectus carinatum deformity divides into two main subgroups, vertically, according to where the bump is located.
- Chondrogladiolar, or Lower (Middle and lower parts of the breastbone protrude and arch forward) – Most common
- Condromanubrial, or Upper (Upper part of the breastbone protrudes) – Less Common
Chondrogladiolar prominence and chondromanubrial are the two primary and most known kinds of pectus carinatum deformity. A mix of chondrogladiolar and chondromanubrial forms can occur in some people.
Pectus carinatum affects the lower sternal costal cartilage, forcing the sternum forward.
Low Pectus Carinatum
A typical low carinatum deformity is defined by a massively protruding sternum, especially in the lower and middle parts. That’s nearly always followed by lower bilateral costal depression, caused by the downward curvature of costal cartilages and the ends of the ribs.
A lateral view chest X-ray reveals anterior sternal protrusion, joint, and sternum. The sternal ossification can depend on the individual’s age. This type of deformity can be present from birth in a small number of individuals.
It becomes more visible gradually throughout adolescence when development is more noticeable.
Most Frequent Type
This is the most frequent type of this malformation. The sternum’s central and bottom sections protrude and arch forward. In 30 to 50 percent of instances, the deformity is asymmetric.
Patients with a combined pectus carinatum and pectus excavatum are uncommon.
Upper Pectus Carinatum
Protrusion of the manubriosternal joint with depression or Currarino-Silverman syndrome is all alternative name for upper pectus carinatum. It combines the upper sternal gap protrusion proximal to the mesosternum and lower pseudo-depression.
Bilaterally there is a protrusion from the second to the ninth costal cartilage. Frequently, upper pectus carinatum can be incorrectly diagnosed. They make a diagnostic mistake, and the upper pectus carinatum is interpreted as pectus excavatum.
Upper Pectus Carinatum Classification
Doctors separate the upper pectus carinatum into two categories:
- Upper pectus carinatum without mesosternal depression
- Upper pectus carinatum with mesosternal depression
Some experts believe that a mixed form of pectus carinatum and pectus excavatum happens because of pseudo-depression, but other authors disagree.
Chondromanubrial prominence is a more complicated and uncommon form of pectus carinatum deformity that accounts for around 5% of the cases.
This deformity has a top section of the sternum protruding anteriorly and a sternum that deviates posteriorly. In a side view, the patient’s sternum has a Z-shape.
Upper Pectus Carinatum Explained
An arching sternum, occasionally S-shaped, appears as a single bone on a lateral view chest X-ray, shorter than expected, with the complete fusion between the body and the sternal notch.
The manubriosternal joint is absent with the obliteration of sternal cartilaginous growth plates. The ossification (production of a new bone) of all nuclei of the sternal scientists cannot detect the regions of the cartilaginous growth plates in the four sternal segments due to their fusion.
The absence of ossification ( production of a new bone) of the manubriosternal joint in two individuals, seen at their first medical visit at the age of four, suggests its likely congenital origin.
The periosteum is thinner than usual, and ocular and electronic microscopy investigations of resected cartilages in the upper pectus carinatum demonstrate degenerative exchanges in hyaline cartilages and abnormal fibrils, as well as a decreased number of chondrocytes.
Similar to those mentioned above, other strange types of pectus carinatum exist but are infrequent. Costal protrusions are discrete changes of the costal cartilages that might be upper or lower, unilateral or bilateral.
An uneven Pigeon Chest May Not be Noticeable
The uneven pigeon breast is usually not particularly noticeable in many cases. The bulge in the deformed breast develops in patients until they are approximately ten years old. The deformity is generally visible in infancy, unlike pectus excavatum.
Physical complaints can show a possibility of a pectus carinatum deformity. It can, however, occur while the child is involved in playing sports or other physical activities.
If the deformity is particularly severe and constricts the lungs, the child may experience breathing problems. Depending on the severity, shortness of breath can be a common side effect of exercise. Patients who lay down on their stomachs may feel uncomfortable in the protrusion area.
Pectus Index ( PI )
In pectus carinatum, the diagnostic process includes clinical metrics. They assist and rate the form and severity of the chest wall deformation.
The Cross-Sectional Chest Wall Ratio (CSCR) or Pectus Index (PI) is a measurement metric. It can collect all information during evaluation, bracing treatment, or before and after surgery. The more severe the pectus carinatum deformity is, the closer the ratio is to 1.0.
The more protruding the chest, the more complex the deformation is.
The Pectus Index (PI) works when you calculate the ml (the width of the chest wall mediolateral) and ap (the depth of the chest wall anteroposterior). The PI is in centimeters, at the level of the nipples and between the spine and anterior chest wall, at the level of the breastbone peak.
Pectus carinatum can also be categorized based on the etiology and when doctors first noticed the deformity. The following are some of the classifications:
- When the sternum does not heal adequately following surgery, it is called post-surgical.
- When the chest protrudes forward at birth, it is congenital.
- The most prevalent variety of pectus carinatum is idiopathic, which arises between 11 and 15 and is associated with growth spurts.
The Bottom Line
Pectus carinatum is a rare chest wall malformation. It is the second most common congenital chest wall abnormality, following pectus excavatum.
The deformity appears in early childhood and generally worsens during puberty. This deformity lowers the patient’s body satisfaction and can lead to self-consciousness and depression.
Luckily for the patients, they can correct their deformities either surgically or non-surgically. You need to know the ins and outs to find the best treatment for you.
Chondrogladiolar prominence (CG) and chondromanubrial prominence (CM) are two types of pectus carinatum. Chondrogladiolar prominence pectus carinatum is the most common manifestation of this deformity.
CM is a less common condition that is more difficult to correct. The middle and lower regions of the rib cage arch forward in patients with CG. The ribs that are longer and more flexible are impacted.
They are easier to correct than the shorter and less flexible ribs in the upper rib cage. CM usually affects the upper rib cage and is symmetrical.
Because the damaged ribs are shorter and less flexible, this variety is more difficult to repair.
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