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Blount disease. A review of etiological factors in 110 patients
Insights
Blount disease, a condition causing leg bowing in children, is prevalent in South Africa's African Negro population. Its exact cause remains unclear, but genetic factors may play a role.
Area of Science:
- Orthopedics
- Genetics
- Pediatrics
Background:
- Infantile Blount disease is notably common in South Africa's African Negro population.
- The condition presents with symmetrical leg bowing, typically appearing with the onset of ambulation.
- No clear link to preceding illness, dietary factors, or other joint involvement was found.
Purpose of the Study:
- To investigate the pathogenesis of infantile Blount disease.
- To identify potential causative factors in a cohort of affected South African children.
Main Methods:
- Retrospective case series analysis of 110 children with infantile Blount disease.
- Clinical examination, family history, and review of relevant medical data.
- Exclusion of common etiological factors such as diet, systemic illness, and traditional carrying positions.
Main Results:
- Equal sex incidence and patchy geographic distribution observed.
- Symmetrical bowing of the legs was the primary presenting feature in 82% of cases.
- No significant differences in developmental milestones, biochemical, or hematological parameters compared to peers.
- Family history suggested a potential multifactorial inheritance pattern rather than simple Mendelian inheritance.
Conclusions:
- The etiology of infantile Blount disease in this population is likely multifactorial.
- Traditional carrying practices and nutritional deficiencies are unlikely primary causes.
- Further research into genetic and environmental interactions is warranted.
Abstract:
The infantile form of Blount disease is common in the African Negro population of South Africa, although it is very rare in other groups in this country. A series of 110 affected children, investigated in an attempt to elucidate the pathogenesis of this condition, demonstrates an approximately equal sex incidence while geographic distribution is patchy. Bowing of the legs, which is symmetrical in 82% is usually the presenting feature and develops at the onset of ambulation. There is no preceding illness, either local or systemic, and no dietary inadequacy. The children do not differ from their peers in age of walking, weight or range of joint movements. There are no biochemical or hematological abnormalities and no radiographic evidence of involvement of joints other than the knees. Twenty-two of the patients had never been carried in the traditional "pick-a-back" position and it is therefore unlikely that this posture is a significant causative factor. The children had a total of 231 siblings, of whom 10 had bowlegs, while 16 parents had been similarly affected during their own infancy. On this basis, Mendelian dominant or recessive inheritance is unlikely although it is possible that Blount disease is multifactorial in etiology.