II. Physiology: Normal Course
- Birth: Maximal varus
- Age 2 years: Neutral position
- Ages 3-4 years: Maximal valgus (>10 degrees)
- Age >10 years: Anatomic valgus at 6 degrees
- Valgus deformity persists more in girls than boys
III. Risk Factors
- Obesity
- Osteogenesis Imperfecta
- Rickets
- Renal Osteodystrophy
- Skeletal Dysplasia
- Klinefelter Syndrome
IV. Signs
- Knock-Kneed appearance
- Evaluate standing knee alignment
- Intermalleolar distance
- Normally 0 cm at birth, 0-5 cm at age 3 years, 0-3 cm at age >=8 years
- Abnormal if >2 SD outside normal values
- Other measurements
- Intercondylar distance
- Tibiofemoral angle
- Intermalleolar distance
V. Precautions
- Onset as teen is unusual and warrants referral
- Atypical acquired cases may result from Trauma, prior Osteomyelitis or Fracture
VI. Differential Diagnosis (Pathologic Genu Valgum)
- Rickets
- Growth Plate Injury
- Prior proximal tibial metaphysis Fracture (Cozen Deformity)
- Diastrophic dysplasia
- Morquio's Syndrome
- Ellis-van Creveld or Chondroectodermal Dysplasia
- Spondyloepiphyseal Dysplasia
- Pseudoachondroplasia
- Rheumatologic Disorders (Genu Valgum-like deformity)
VII. Management: Orthopedic Referral Indications
- Intermalleolar distance outside of normal range for age
- Associated syndrome suspected
VIII. Complications
- Premature Osteoarthritis