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Disease Profile

Blount disease

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

Not yet documented

US Estimated

Europe Estimated

Age of onset






Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Tibia vara; Osteochondrosis deformans tibiae; Blount's disease;


Congenital and Genetic Diseases; Musculoskeletal Diseases


Blount disease is a growth disorder of the shin bone (tibia) characterized by inward turning of the lower leg (bowing) that slowly worsens over time. While it is not uncommon for young children to have bowed legs, typically the bowing improves with age.[1][2] There are two types of Blount disease (early-onset and late-onset), based on whether symptoms begin before or after four years of age.[3] Blount disease may occur in one or both legs and can lead to shortening of the affected leg and other changes within bones of the legs. The cause of Blount disease is not well understood; however, a variety of hereditary and genetic factors are likely involved. The condition is more common among certain populations and is associated with obesity and early walking.[1][4] Treatment may involve bracing and/or surgery.[1]


This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
80%-99% of people have these symptoms
Tibial bowing
Bowed shankbone
Bowed shinbone

[ more ]

30%-79% of people have these symptoms
Abnormality of the knee
Abnormality of the proximal tibial epiphysis
Abnormality of the end part of innermost shankbone
Abnormality of the end part of innermost shinbone

[ more ]

Abnormality of the tibial metaphysis
Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance
Genu varum
Outward bow-leggedness
Outward bowing at knees

[ more ]

Osteochondritis Dissecans


Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

    Social Networking Websites

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      These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

      Where to Start

      • The American Academy of Orthopaedic Surgeons has information on Blount disease. Click on the link above to view this information page.
      • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.

        In-Depth Information

        • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
        • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
        • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
        • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
        • PubMed is a searchable database of medical literature and lists journal articles that discuss Blount disease. Click on the link to view a sample search on this topic.


          1. Neil K. Kaneshiro. Blount disease. In: David Zieve. MedlinePlus. 11/20/2014; https://medlineplus.gov/ency/article/001584.htm.
          2. Bowed legs. American Academy of Orthopaedic Surgeon. https://orthoinfo.aaos.org/topic.cfm?topic=A00230. Accessed 3/19/2009.
          3. Sanjeev Sabharwal. Blount disease. J Bone Joint Surg Am. Jul 01 2009; 91 (7):1758-1776. https://www.ncbi.nlm.nih.gov/pubmed/19571101.
          4. Lauren LaMont, MD. Blount disease. Medscape. Dec 17, 2015; https://emedicine.medscape.com/article/1250420.