How Common are Congenital Rib Abnormalities?

Patient Presentation
A 21-year-old female came to clinic with 3-4 days of right upper back pain. She denied any trauma but had fallen on some ice without any obvious injury around the same time. She said that the pain was worse with carrying her book bag, picking up groceries and after sleeping. She had used some ibuprofen once with some relief. She said she sometimes had some neck pain in the same area also but denied any headache, arm pain or anterior chest pain. She had no respiratory problems, fever, chills or sweats.

The past medical history was non-contributory The family history was positive for member with an unknown “spine problem” that reportedly wasn’t diagnosed promptly. The review of systems was otherwise negative.

The pertinent physical exam showed a healthy female with normal vital signs. Her examination was normal except for pain in the trapezius and levator scapulae muscles on the right side. No deltoid, latissimus dorsi or infraspinatus muscles appeared affected. Pain was in the areas of the supraspinatus and rhomboid muscles mainly. There was no pain on the left side. She had full range of motion in her neck, bilateral shoulders and also spine with flexion, extension and rotation. There was no pain over any bony prominences.

The diagnosis of a muscle strain was made and conservative treatment was recommended. The patient was insistent that a radiograph be obtained because of the family history. The radiologic evaluation of spinal radiographs of the upper thorax and neck were negative, but on the chest radiograph the left side had a probable rib abnormality. A computed tomographic study was ordered. The patient’s clinical course showed that while awaiting the computed tomography her pain resolved.

Case Image
CXR (above) suggests a fusion anomaly of the left first and second ribs anteriorly which is better demonstrated on the 3D CT reconstruction (below) which shows a small bony projection from the left lateral second rib forming a pseudoarthrosis with the left first rib. This was felt to be a congenital anomaly.

The embryonic mesoderm forms the skeletal system. The mesoderm is further divided into the dorsal, sclerotome and ventral dermatome. The sclerotome forms the ribs which are under the influence of various genes and growth factors. Congenital rib abnormalities occur in number ( the normal 12 ribs) or in formation/structural. Malformations can include hypoplastic, bridging, forked, fused and hypoplastic ribs. Even ribs with holes occur because of the segmentation issues. Illustrated examples can be found here. The rib’s cartilage, bone or both can be affected. Location along the rib is also variable. Abnormalities can be unilateral or bilateral.

Most abnormalities do not cause problems. Some do however and the problems are usually related to their location. Extranummerary cervical or intrathoracic ribs can cause problems with potential nerve compression, or compression of the subclavian artery or lymphatics in the area. Rib abnormalities in other areas have been reported to cause liver laceration or pneumothorax.

A review of back pain can be found here.

Learning Point
Congenital rib abnormalities affect ~1% of patients and most do not cause problems Many are found incidentally. Chest computed tomography, often recently with 3-D reconstruction, helps to delineate the abnormality and potentially the treatment. Treatment is usually conservative but sometimes resection is necessary.

In a radiological study of congenital rib abnormalities where participants (N=650) were referred for chest computed tomography, 35.5% were female and 64.5% were male, with a mean age of 21 years. The most common numeric abnormalities were in cervical ribs (3.6%), thoracic ribs (0.15%) and lumbar ribs (1.3%). The most common structural abnormalities were bifid rib (6.7%) and fused ribs (2.6%).

An Illustrated Atlas of Human Variation has good discussions with images for various types of rib abnormalities.
It can be found here

Questions for Further Discussion
1. How are pectus abnormalities identified and treated?
2. What other types of skeletal segmentation problems can be identified?
3. What are indications for consultation with a radiologist?
4. What is the difference between a malformation and a deformation? It can be reviewed here

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Birth Defects

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Coyan G, Daon E. Resection of supernumerary intrathoracic rib using robotic-assisted video-assisted thoracoscopic surgery. Surg Radiol Anat SRA. 2016;38(4):415-417. doi:10.1007/s00276-015-1574-9.

Davran R, Bayarogullari H, Atci N, Kayali A, Ozturk F, Burakgazi G. Congenital abnormalities of the ribs: evaluation with multidetector computed tomography. JPMA J Pak Med Assoc. 2017;67(2):178-186.

Kabakus IM, Atceken Z, Ariyurek OM. Expansion of the Rib Head: A Novel Computed Tomographic Feature of Supernumerary Intrathoracic Ribs. Eurasian J Med. 2017;49(1):64-65. doi:10.5152/eurasianjmed.2017.17004

Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa