|Year : 2015 | Volume
| Issue : 5 | Page : 670-671
Bifid rib: A rare anomaly
Mythili Krishnan Rathinasabapathi, Haresh Kumar Perumallapalli
Department of Anatomy, Armed Forces Medical College, Pune, Maharashtra, India
|Date of Web Publication||10-Sep-2015|
Mythili Krishnan Rathinasabapathi
Department of Anatomy, Armed Forces Medical College, Pune - 411 040, Maharashtra
Source of Support: Nil., Conflict of Interest: None declared.
A case of the bifid rib was found during routine bone study. The distal part of the osseous rib bifurcated into two divisions with an angle of 60°. Both divisions had their own costal cartilage. Bifid rib is a congenital abnormality of the rib cage and usually asymptomatic, often discovered incidentally on chest X-ray. Effects of this neuroskeletal anomaly can include respiratory difficulties and neurological limitations.
Keywords: Bifurcated rib, chest wall anomaly, intrathoracic rib
|How to cite this article:|
Rathinasabapathi MK, Perumallapalli HK. Bifid rib: A rare anomaly. Med J DY Patil Univ 2015;8:670-1
| Introduction|| |
A bifid rib (also bifurcated rib) is a congenital neuroskeletal abnormality of the anterior chest wall, which occurs in about 1.2% of humans. The sternal end of the rib is cleaved into two. It is usually unilateral.
The overall prevalence of the bifid rib is estimated at 0.15-3.4% (mean 2%), and it accounts for up to 20% of all congenital rib anomalies. Rib anomalies are noted in 0.31% of routine chest radiographs.
Most commonly it occurs in 4th rib. Asymptomatic and often discovered incidentally by chest X-ray. A bicipital rib is different from the bifid rib and is seen in relation to the first thoracic rib. It appears to be the result of the fusion of two ribs, either of a cervical and first thoracic or of the first two thoracic ribs.
| Observation|| |
During routine study of bones in Department of Anatomy, we found a left rib with bifurcation at the anterior end of the bone as shown in [Figure 1].
Rib shows head with articular facets, tubercles, angle, and costal groove as of a typical rib as shown in [Figure 2].
|Figure 2: Medial view of the left bifurcated rib with features of a typical rib|
Click here to view
| Discussion|| |
A rib normally develops from the costal process of the developing thoracic vertebrae. Embryologically, development of the bifid rib is uncertain and probably results from incomplete fusion of cephalic and caudal segments of sclerotome during embryogenesis, occurring around the 4th-6th week of fetal life. During the mesenchymal and chondrogenic state of development, faulty fusion or anomalous chondrification may give rise to unusual fusion deformities of the ribs (bifid ribs), has been suggested as a possible cause.
Ribs originate from the mesoderm. Bifid ribs may, therefore, be associated with other mesodermal abnormalities. Look specifically for malformations in other organs of mesodermal origin that is heart and kidneys.
These anomalies are generally more common in females than in males, occur more frequently on the right side and they are usually asymptomatic. Type II intrathoracic rib is a so-called bifid intrathoracic rib.
The distal parts of the osseous rib bifurcated with an angle of 60° and both of the divisions had their own costal cartilage. The costal cartilage fused again to form the trunk that was connected to the sternum. The space between the two divisions was filled with presumably normal intercostal muscles. Blood supply was maintained by a small branch from the internal thoracic artery to the upper divisions. However, the intercostal nerves did not branch toward the upper branch, but only ran along the lower margins of the lower divisions of the bifid ribs.
Gorlin-Goltz (basal cell nevus) syndrome (65-70% of patients), Job's syndrome, Kindler syndrome, malignancy in childhood (esp neuroblastoma). Very rarely a bifid rib may occur as part of Gorlin-Goltz syndrome or Jobs syndrome or Kindler syndrome.
| Conclusion|| |
The anomalies of the bones are less common to find. There is little information in the literature about the clinical significance of bifid ribs. Rib anomalies can occur in isolation or as part of vertebral malformations.
Knowledge of bifid ribs is necessary for the differential diagnosis with other diseases, such as tumors of the chest wall or costal fracture, because the various types of the bifid rib are present with diverse appearances on normal chest X-rays.
The presence of an additional rib and intercostal space can mislead in rib and intercostal space counting during the postmortem examination and may lead to incorrect interpretation especially, while describing the thoracic injuries.
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[Figure 1], [Figure 2]