Normal Intercondylar Distance at 4 Years of Age
At 4 years of age, the normal intercondylar distance should be 0 cm (no measurable distance), as children at this age typically exhibit physiologic genu valgum (knock-knee) rather than genu varum (bowlegs). 1
Age-Specific Normal Values
By 18-24 months, normal children progress from physiologic bowlegs to neutral knee alignment (0 degrees), and any measurable intercondylar distance after this age is abnormal 1
At 4 years of age, children reach their peak knock-knee alignment (approximately 8 degrees of valgus), meaning the knees touch and there is no intercondylar distance to measure 1
Instead of intercondylar distance, intermalleolar distance becomes the relevant measurement at age 4, with normal values up to 8 cm in children aged 2-11 years 1
Clinical Interpretation and Red Flags
Any measurable intercondylar distance (genu varum/bowlegs) persisting beyond 2 years of age is abnormal and warrants investigation for pathologic causes. 1
If an intercondylar distance of more than 4 cm is present at 18 months or beyond, this strongly suggests pathologic genu varum requiring further workup 2
The American College of Medical Genetics and Genomics emphasizes that persistent or worsening intercondylar distance after age 2 years necessitates consideration of metabolic causes including X-linked hypophosphatemia (XLH), rickets, or Blount disease 3
Measurement Technique
Proper measurement requires the child to stand erect with feet together, knees fully extended, and measuring the distance between the medial femoral condyles at their closest point when the medial malleoli (ankle bones) are touching 3
Measurements should be documented at each clinical visit alongside height and growth velocity to track any progression or improvement 3
Important Clinical Caveats
These measurements represent only one component of lower limb assessment and cannot replace comprehensive orthopedic evaluation, as they do not capture limb torsion, rotational abnormalities, or combined deformities 3
Asymmetric deformities (one leg with varus, the other with valgus) require immediate orthopedic referral regardless of the measured distances 3
If pathologic genu varum is suspected based on persistent intercondylar distance at age 4, biochemical evaluation should include serum phosphate, alkaline phosphatase, vitamin D levels, and parathyroid hormone to identify metabolic causes 4