How do you measure intercondylar distance in a child?

How to Measure Intercondylar Distance in Children

Measure the intercondylar distance by having the child stand erect with feet together and knees extended, then measure the distance between the medial femoral condyles at their closest point when the medial malleoli are touching. 1

Measurement Technique

Patient Positioning

• Have the child stand upright with feet together and knees fully extended 2, 3
• The child should face the examiner with weight evenly distributed on both legs 2
• Ensure the medial malleoli (inner ankle bones) are touching each other 2, 3

Taking the Measurement

• Measure the shortest distance between the two medial femoral condyles (the bony prominences on the inner aspect of the knees) 2, 3, 4
• Use a measuring tape or caliper to record the distance in centimeters 2, 3
• Measure to the nearest 0.1 cm for accuracy 2
• Take the measurement at the point where the condyles are closest together 3

Clinical Context and Interpretation

Normal Values by Age

• At 6 months to 2 years: Children are normally bowlegged, so intercondylar distance measurement is not typically performed 2
• Ages 2-11 years: Normal intercondylar distance should be 0 cm (knees touching) as physiologic genu varum resolves by age 2 years 2
• Any measurable intercondylar distance after age 2 years is abnormal and warrants further evaluation 2

When to Measure Intermalleolar Distance Instead

• If the knees touch (intercondylar distance = 0), measure intermalleolar distance instead to assess for genu valgum (knock knees) 1, 2
• Normal intermalleolar distance in children aged 2-11 years can be up to 8 cm 2
• Maximum physiologic genu valgum occurs around age 4 years 2, 4

Important Clinical Caveats

Limitations of the Measurement

• Intercondylar and intermalleolar distances vary significantly with age and cannot replace comprehensive orthopedic assessment 1
• These measurements do not capture the complexity of leg deformities such as limb torsion, rotational abnormalities, or combined deformities 1
• Always correlate clinical measurements with radiographic assessment when substantial limb deformities are present 1

Red Flags Requiring Further Evaluation

• Persistent or worsening intercondylar distance after age 2 years suggests pathologic genu varum 2
• Consider metabolic causes such as X-linked hypophosphatemia (XLH), rickets, or Blount disease in these cases 1, 5
• Asymmetric deformities (windswept deformity with varus on one side and valgus on the other) require immediate orthopedic referral 1

Serial Monitoring

• Measure intercondylar/intermalleolar distance at each clinical visit to track progression or improvement 1
• Document measurements alongside height and growth velocity for comprehensive assessment 1
• Changes in these measurements help evaluate response to treatment in conditions like XLH 1, 5