Genu Varum Causes and Management

Metabolic and Systemic Causes

X-linked hypophosphatemia (XLH) is a significant cause of genu varum, characterized by renal phosphate wasting and elevated FGF23 levels, according to the Nature Reviews Nephrology 1, 2
The Nature Reviews Nephrology recommends considering XLH in cases of genu varum, as it can cause severe leg bowing, partial fraying, and irregularity of the distal femoral and proximal tibial growth plates 2

Genu varum may present with varying degrees of severity, from mild cosmetic concerns to significant functional impairment, as reported by Praxis Medical Insights: Practical Summaries of Clinical Guidelines 3
The Nature Reviews Nephrology suggests that assessment should include measurement of intercondylar distance to quantify the severity of the deformity 4

Biochemical evaluation should be considered in persistent cases to rule out metabolic causes, including serum phosphate, alkaline phosphatase, vitamin D levels, and parathyroid hormone, according to the Nature Reviews Nephrology 1
In XLH, hypophosphatemia, elevated alkaline phosphatase, and elevated FGF23 levels are characteristic findings, as noted by the Nature Reviews Nephrology 5
Genetic testing may be necessary in suspected hereditary conditions like XLH, where PHEX gene mutations are found in approximately 70-90% of cases, as reported by the Nature Reviews Nephrology 6

Untreated genu varum can lead to abnormal gait and decreased mobility, as noted by the Nature Reviews Nephrology 1
Progressive joint damage and early osteoarthritis can occur in untreated genu varum, according to Praxis Medical Insights: Practical Summaries of Clinical Guidelines 3
Decreased growth velocity and disproportionate short stature can occur in cases like XLH, as reported by the Nature Reviews Nephrology 5

The Nature Reviews Nephrology recommends that treatment approach depends on the underlying cause, severity of deformity, age of the patient, and functional impairment, and that specific treatments addressing the underlying disorder (phosphate supplementation and active vitamin D) can improve the bowing in metabolic causes like XLH 4
Regular monitoring of growth and development is essential in children with genu varum, as suggested by the Nature Reviews Nephrology 4

In children with bilateral leg pain, fatigue after walking short distances can reflect musculoskeletal weakness due to vitamin D deficiency. 8