Rarely, metaphyseal chondroplasia causes genu varum due to abnormal chondroblast function and chondroid production. Short stature and mental retardation may be present. Achondroplasia, causing dwarfism by defective endochondral bone formation, results in physiological tibia vara which doesn't correct with growth due to overgrowth of the fibula. Bracing is ineffective due to joint laxity, so proximal fibula epiphysiodesis or tibial osteotomy are recommended. Osteogenesis imperfecta, in which there is a collagen defect and diffuse osteopaenia, results in bowing and twisting of the femur due to repeated fractures.
Treatment is by bracing or surgery.
Focal fibrocartilagenous dysplasia affects the proximal medial tibia, causing tibia vara by 18 months that corrects with growth by 4 years. Radiologically, cortical lucency surrounded by sclerosis is visible in the metaphysis. Short stature increases the likelihood of a constitutional cause of genu varus. In all cases, the aim of treatment is to restore the mechanical axis and prevent later osteoathritis.