[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Embryology](https://durgical.com/en/embryology/) › [Skeleton, muscles, limbs and skin](https://durgical.com/en/embryology/#a-musculoskeletal) › Hemivertebra, congenital scoliosis and Klippel–Feil [Embryology](https://durgical.com/en/embryology/) · [Skeleton, muscles, limbs and skin](https://durgical.com/en/embryology/#a-musculoskeletal) # Hemivertebra, congenital scoliosis and Klippel–Feil - Malformation If a vertebra forms only halfway or two vertebrae stay stuck together, the spine is curved from birth. Updated 2026-11-01 **See it in 3D:** [Axis (C2)](https://durgical.com/en/anatomy/axis/) · [C3 vertebra](https://durgical.com/en/anatomy/cervical-vertebrae/) · [C4 vertebra](https://durgical.com/en/anatomy/c4/) · [C5 vertebra](https://durgical.com/en/anatomy/c5/) · [C6 vertebra](https://durgical.com/en/anatomy/c6/) · [C7 vertebra](https://durgical.com/en/anatomy/vertebra-prominens/) · [T1 vertebra](https://durgical.com/en/anatomy/t1/) · [T12 vertebra](https://durgical.com/en/anatomy/t12/) · [L1 vertebra](https://durgical.com/en/anatomy/lumbar-vertebra/) · [Scapula](https://durgical.com/en/anatomy/scapula/) · [Ribs (back part)](https://durgical.com/en/anatomy/ribs/) ## Key points - Hemivertebra = failure of formation; block or bar = failure of segmentation. - Unilateral bar + contralateral hemivertebra = the scoliosis that progresses most. - Klippel–Feil: short neck, low hairline, limited movement; Sprengel is common. - Look at kidney, heart and spinal cord (MRI). - Abnormal vertebrae = the V of VACTERL. ## What it is Congenital vertebral anomalies come from errors in weeks 4 to 6, while the somites segment and the sclerotome builds the vertebrae. There are failures of formation (hemivertebra, wedge vertebra) and failures of segmentation (block vertebra, unsegmented bar). They cause congenital scoliosis and, in the neck, Klippel–Feil syndrome. Because they arise at the same time as other organs, kidney, heart and spinal cord anomalies must be looked for. ## Embryological cause - Failure of formation: a chondrification centre on one side does not form, leaving a hemivertebra or a wedge vertebra. - Failure of segmentation: two sclerotomes do not separate; if complete it gives a block vertebra, if one-sided a bar. - The somite segmentation clock (Notch pathway: DLL3, MESP2, HES7, LFNG) is key; its mutations cause spondylocostal dysostosis. - Klippel–Feil: failed separation of cervical vertebrae; known genes GDF6, GDF3 and MEOX1, though many cases have no known cause. - Sprengel deformity: the scapula forms at cervical level and fails to descend. ## Markers - DLL3 - MESP2 - HES7 - GDF6 - MEOX1 - VACTERL ## How it presents - Congenital scoliosis: the worst progression is a one-sided unsegmented bar with a hemivertebra on the other side. - Klippel–Feil: short neck, low posterior hairline and limited movement; fewer than half have all three signs. - Klippel–Feil is associated with Sprengel deformity (20 to 30 %), scoliosis, hearing loss, kidney and heart anomalies. - Vertebral anomalies are part of the VACTERL association (vertebral, anal, cardiac, tracheo-oesophageal, renal, limb). - Anomalies within the canal (tethered cord, diastematomyelia) are common. ## Diagnosis - X-ray of the whole spine to count and classify the vertebrae. - Spinal MRI to look for tethered cord or other canal anomalies. - Routine renal ultrasound and echocardiogram. - In Klippel–Feil, flexion–extension views of the cervical spine for possible instability. ## Memory aid In the congenital spine 'a half vertebra pushes and a bar ties down': together, the curve never stops. ## Test yourself Think of the answer, then tap the question to see it. ## How does a hemivertebra differ from a block vertebra? A hemivertebra is a failure of formation of half a vertebra; a block vertebra is a failure of segmentation between two. ## What is the classic triad of Klippel–Feil syndrome? Short neck, low posterior hairline and limited neck movement. ## Which combination of anomalies gives the most progressive congenital scoliosis? An unsegmented bar on one side with a hemivertebra on the opposite side. ## Which other organs are studied in a child with congenital scoliosis? Kidneys (ultrasound), heart (echocardiogram) and spinal cord (MRI). [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/embryology/hemivertebra-congenital-scoliosis-and-klippel-feil/) ## See it in 3D The structures of Durgical's 3D anatomy where it is found. - [Axis (C2)](https://durgical.com/en/anatomy/axis/) - [C3 vertebra](https://durgical.com/en/anatomy/cervical-vertebrae/) - [C4 vertebra](https://durgical.com/en/anatomy/c4/) - [C5 vertebra](https://durgical.com/en/anatomy/c5/) - [C6 vertebra](https://durgical.com/en/anatomy/c6/) - [C7 vertebra](https://durgical.com/en/anatomy/vertebra-prominens/) - [T1 vertebra](https://durgical.com/en/anatomy/t1/) - [T12 vertebra](https://durgical.com/en/anatomy/t12/) - [L1 vertebra](https://durgical.com/en/anatomy/lumbar-vertebra/) - [Scapula](https://durgical.com/en/anatomy/scapula/) - [Ribs (back part)](https://durgical.com/en/anatomy/ribs/) ## Related - [Vertebrae: resegmentation of the sclerotomes](https://durgical.com/en/embryology/vertebrae-resegmentation-of-the-sclerotomes/) - [Paraxial mesoderm and somites: sclerotome, myotome, dermatome](https://durgical.com/en/embryology/paraxial-mesoderm-and-somites-sclerotome-myotome-dermatome/) - [Neural tube defects: anencephaly, spina bifida and encephalocele](https://durgical.com/en/embryology/neural-tube-defects-anencephaly-spina-bifida-and-encephalocele/) - [Muscles: somites, epaxial and hypaxial](https://durgical.com/en/embryology/muscles-somites-epaxial-and-hypaxial/) - [Anorectal malformations (imperforate anus)](https://durgical.com/en/embryology/anorectal-malformations/) - [Esophageal atresia and tracheoesophageal fistula](https://durgical.com/en/embryology/esophageal-atresia-and-tracheoesophageal-fistula/) ## Related conditions - [Scoliosis](https://durgical.com/en/conditions/scoliosis/) - [Torticollis](https://durgical.com/en/conditions/torticollis/) - [Spina bifida (myelomeningocele)](https://durgical.com/en/conditions/spina-bifida/) [← All of embryology](https://durgical.com/en/embryology/) Educational content on embryonic development; not a guide to prenatal diagnosis or to medicines in pregnancy and no substitute for a health professional's advice. No doses are given. Sources: [Klippel-Feil syndrome: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/klippel-feil-syndrome/) (MedlinePlus, US National Library of Medicine, 2026); [Spondylocostal dysostosis: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/spondylocostal-dysostosis/) (MedlinePlus, US National Library of Medicine, 2026); Langman's Medical Embryology, 13th ed., ch. 10: The Axial Skeleton (Wolters Kluwer, 2015). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/embryology/hemivertebra-congenital-scoliosis-and-klippel-feil/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/embryology/hemivertebra-congenital-scoliosis-and-klippel-feil/