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

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

(shin bone) which causes the lower leg to angle inward, resembling a bowleg. It is also known as "tibia vara".

Signs and symptoms

Cause

Blount disease is a growth disorder of the shin bone which causes the lower leg to angle inward, resembling a bowleg. 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.

Diagnosis

Differential diagnosis

Lower extremity deformities in

rickets Rickets, scientific nomenclature: rachitis (from Greek , meaning 'in or of the spine'), is a condition that results in weak or soft bones in children and may have either dietary deficiency or genetic causes. Symptoms include bowed legs, stun ...

can closely mimic those produced by Blount's disease. To differentiate between rickets 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 (ALP, alkaline phenyl phosphatase, also abbreviated PhoA) is a phosphatase with the physiological role of dephosphorylating compounds. The enzyme is found across a multitude of organisms, prokaryotes and eukaryo ...

. Besides the X-ray appearance. Bone deformities in rickets 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 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 (BMI >35), which are an indication for

bariatric surgery Bariatric surgery (also known as metabolic surgery or weight loss surgery) is a surgical procedure used to manage obesity and obesity-related conditions. Long term weight loss with bariatric surgery may be achieved through alteration of gut ho ...

in children per a 2019 policy statement of the

American Academy of Pediatrics The American Academy of Pediatrics (AAP) is the largest professional association of pediatricians in the United States. It is headquartered in Itasca, Illinois, and maintains an office in Washington, D.C. The AAP has published hundreds of poli ...

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

GERD Gastroesophageal reflux disease (GERD) or gastro-oesophageal reflux disease (GORD) is a chronic upper gastrointestinal disease in which stomach content persistently and regularly flows up into the esophagus, resulting in symptoms and/or ...

, and hypertension.

Etymology

Blount disease is named after Walter Putnam Blount (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.Nilsonne, H. (1929) Genu varum mit eigentümlichen Epiphysenveränderungen. Acta chir. scand. 44, 187. it is today considered an acquired disease of the proximal tibial metaphysis rather than an epiphyseal dysplasia or osteochondrosis.

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