Description

• Angling of the knee(s) toward the midline, giving the appearance of the knees touching while the ankles are apart
• Classified as physiologic and/or pathologic
• Physiologic genu valgum is a normal stage in the growth and development of healthy children between the ages of 2 and 7 years.
• Pathologic genu valgum if
  • The extent of angulation is greater than the mean for that particular age.
  • The deformity persists beyond the age-appropriate progression of valgus.
  • There is an underlying etiology.

Epidemiology

Prevalence
Physiologic genu valgum is a normal variant in children 2 to 7 years of age. It is more common in females.

Etiology and Pathophysiology

• Physiologic genu valgum
  • Lower extremity alignment in childhood progresses from varus to valgus in the first 2 years of life.
  • Around 2 years of age, lower extremity alignment progresses to valgus until it reaches a maximum (peak valgus angulation of 10 to 15 degrees) at approximately 4 years of age.
  • Most children reach neutral adult alignment (~5 degrees) by 7 years of age.
• Etiologies of pathologic genu valgum include:
  • Physeal/bone damage
    • Trauma (e.g., proximal tibia metaphyseal)
    • Infection
    • Inflammatory disease (e.g., rheumatoid arthritis)
  • Metabolic disease
    • Rickets
    • Renal osteodystrophy
  • Skeletal dysplasias
    • Pseudoachondroplasia
    • Metaphyseal dysplasia
    • Multiple epiphyseal dysplasia
  • Neoplasms
    • Multiple hereditary exostoses
    • Osteochondromas
    • Other benign tumors
  • Other
    • Iliotibial band tightness
    • Vascular compromise
    • Neuromuscular disease
    • Obesity
    • Idiopathic

Genetics
Idiopathic genu valgum is heritable.

Risk Factors

• Family history of genu valgum
• Proximal tibia metaphyseal fracture (Cozen fracture)
• Obesity

Commonly Associated Conditions

Flat feet and external tibial torsion frequently accompany physiologic genu valgum. When present, this often accentuates the appearance of valgus.