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Genu Varum (Bowlegs) and Genu Valgum (Knock-Knees)


Simeon A. Boyadjiev Boyd

, MD, University of California, Davis

Reviewed/Revised Sep 2022
Topic Resources

Genu varum

Genu varum is common among toddlers and usually resolves spontaneously by age 18 months. If it persists or becomes more severe, Blount disease (tibia vara) should be suspected, and rickets Hypophosphatemic Rickets Hypophosphatemic rickets is a genetic disorder characterized by hypophosphatemia, defective intestinal absorption of calcium, and rickets or osteomalacia unresponsive to vitamin D. It is usually... read more and other metabolic bone diseases should also be ruled out.

Blount disease is due to a growth disturbance of the medial aspect of the proximal tibial growth plate; genu varum and tibial torsion Tibial Torsion The tibia may be twisted at birth. Tibial torsion can be external (lateral) or internal (medial). (See also Introduction to Congenital Craniofacial and Musculoskeletal Disorders.) External tibial... read more may occur. Blount disease may occur in early childhood or in adolescence (when it is associated with overweight). Early diagnosis of Blount disease is difficult because x-rays may be normal; the classic x-ray finding is angulation (beaking) of the medial metaphysis. Early use of splints or braces can be effective, but surgery with or without an external fixator is often needed.

Genu valgum

Genu valgum is less common than genu varum and, even if severe, usually resolves spontaneously by age 9 years. Skeletal dysplasia or hypophosphatasia Congenital Hypophosphatasia Congenital hypophosphatasia is absence or low levels of serum alkaline phosphatase due to mutations in the gene encoding tissue-nonspecific alkaline phosphatase (TNSALP). Because serum alkaline... read more should be excluded. If marked deformity persists after age 10 years, surgical stapling of the medial distal femoral epiphysis is indicated.

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