Blount's disease (or Blount disease) is a growth disorder of the

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

(shin bone) which causes the lower leg to angle inward, resembling a

bowleg Genu varum (also called bow-leggedness, bandiness, bandy-leg, and tibia vara) is a varus deformity marked by (outward) bowing at the knee, which means that the lower leg is angled inward ( medially) in relation to the thigh's axis, giving the ...

. It is also known as "tibia vara".

Description and risk factors

Blount disease is a growth disorder of the

shin bone The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

which causes the lower leg to angle inward, resembling a

. It can present in boys under 4-years in both legs, or in adolescents usually on one side. Causes are thought to be genetic and environmental, like obesity, African-American lineage, and early walkers.Dakshina Murthy T S. S; Alessandro De Leucio
Blount Disease
Treasure Island (FL): StatPearls Publishing; 2022 January.

Etymology

Blount disease is named after

Walter Putnam Blount Walter may refer to: People * Walter (name), both a surname and a given name * Little Walter, American blues harmonica player Marion Walter Jacobs (1930–1968) * Gunther (wrestler), Austrian professional wrestler and trainer Walter Hahn (born 19 ...

(1900–1992), an American pediatric orthopedic surgeon, who described it in 1937. It has also been known as Mau-Nilsonne Syndrome, after C. Mau and H. Nilsonne, who published early case reports of the condition. it is today considered an acquired disease of the proximal tibial metaphysis rather than an epiphyseal dysplasia or osteochondrosis.

Diagnosis

Differential Diagnosis

Lower extremity deformities in

Rickets Rickets is a condition that results in weak or soft bones in children, and is caused by either dietary deficiency or genetic causes. Symptoms include bowed legs, stunted growth, bone pain, large forehead, and trouble sleeping. Complications may ...

can closely mimic those produced by Blount's disease. To differentiate between

and Blount's disease it is important to correlate the clinical picture with laboratory findings such as calcium, phosphorus and

alkaline phosphatase The enzyme alkaline phosphatase (EC 3.1.3.1, alkaline phosphomonoesterase; phosphomonoesterase; glycerophosphatase; alkaline phosphohydrolase; alkaline phenyl phosphatase; orthophosphoric-monoester phosphohydrolase (alkaline optimum), systematic ...

. Besides the X-ray appearance. Bone deformities in

have a reasonable likelihood to correct over time, while this is not the case with Blount's disease. Nevertheless, both disorders may need surgical intervention in the form of bone osteotomy or more commonly guided growth surgery.

Osteochondrodysplasias Osteochondrodysplasia is a general term for a disorder of the development (dysplasia) of bone ("osteo") and cartilage ("chondro"). Osteochondrodysplasias are rare diseases. About 1 in 5,000 babies are born with some type of skeletal dysplasia. Non ...

or genetic bone diseases can cause lower extremity deformities similar to Blount's disease. The clinical appearance and the characteristic radiographic are important to confirm the diagnosis.

Treatment

Children who develop severe bowing before the age of 3 may be treated with knee ankle foot orthoses. However, bracing may fail, or bowing may not be detected until the child is older. Bracing should be started by 3 years of age. In some cases, surgery may be performed. Blount disease is one of the 8 severe comorbidities of

severe obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's we ...

(BMI >35), which are an indication for

bariatric surgery Bariatric surgery (or weight loss surgery) includes a variety of procedures performed on people who are obese. Long term weight loss through the standard of care procedures ( Roux en-Y bypass, sleeve gastrectomy, and biliopancreatic diversion ...

in children per a 2019 policy statement of the

American Academy of Pediatrics The American Academy of Pediatrics (AAP) is an American professional association of pediatricians, headquartered in Itasca, Illinois. It maintains its Department of Federal Affairs office in Washington, D.C. Background The Academy was founded ...

. The other severe comorbidities are: obstructive sleep apnea (Apnea-Hypopnea Index > .5), Type2 Diabetes mellitus, idiopathic intracranial hypertension (IIH), nonalcoholic steatohepatitis, SCFE, GERD, and hypertension.

References

External links

*Dakshina Murthy T S. S; Alessandro De Leucio
Blount Disease
Treasure Island (FL): StatPearls Publishing; 2022 Jan-. {{DEFAULTSORT:Blount's Disease Skeletal disorders Orthopedic problems Knee injuries and disorders Pediatrics Syndromes affecting bones