Leg Length Difference

Leg Length Difference in Children

A leg length difference means one leg appears shorter than the other.

This may be due to either:

True leg length difference – the bones are actually different lengths
Apparent leg length difference – the bones are equal but posture or alignment makes one leg look shorter

True leg length difference

This occurs when one leg bone grows less than the other.

Possible causes

• Idiopathic (unknown cause) – very common
• Clubfoot
• Congenital shortening of the thigh or shin bone
• Hip conditions (DDH, Perthes’ disease, slipped upper femoral epiphysis)
• Previous hip or pelvic surgery
• Neurological conditions (e.g. cerebral palsy, developmental delay)
• Growth plate injury after fracture or infection
• Hemihypertrophy (one side of body larger)
• Tiptoe walking as compensation

Many children are unaware and have no symptoms.

Apparent leg length difference

The legs are equal in length but look unequal due to alignment.

Causes

• Hypermobility and posture
• Tight calf or hamstring muscles
• Tiptoe gait on one side
• Spinal curvature (scoliosis)
• Flat feet or asymmetric arches
• Knock knees or bow legs

What symptoms may occur?

Children may complain of:

• Leg pain after activity
• Fatigue when walking
• Occasionally back pain

How is it assessed?

• Clinical examination
• Tape measurement – simple screening test
• Galeazzi test – compares knee heights when lying down

Imaging (most accurate)

• Standing long-leg X-rays

These measure the difference precisely and identify where it originates.

Additional tests may include:

• Wrist X-ray (bone age)
• Vitamin D blood test
• Spine X-ray if scoliosis suspected

Treatment

Treatment depends on whether the difference is true or apparent and the predicted difference at maturity.

Non-operative treatment

Predicted difference	Treatment
Less than 1 cm	Observation / activity modification
1–2 cm	Insoles or shoe raise

Many children only need monitoring.

Surgical treatment

Surgery is considered if the predicted difference is more than 2 cm.

Before growth finishes (operate on the longer leg)

Epiphysiodesis (temporary growth slowing)

• Small plates across growth plate
• Shorter leg catches up
• Metalwork removed later

Epiphysiolysis (permanent growth stop)

• One-stage procedure
• Used near skeletal maturity

After growth finishes (operate on the shorter leg)

Limb lengthening

• External circular frame applied to bone
• Bone gradually lengthened
• Bone regenerates during the process

Treatment usually lasts several months until bone strengthens fully.

Key message for parents

✔ Small differences are common and often harmless
✔ Many children only need monitoring or shoe raises
✔ Surgery is reserved for larger differences
✔ Timing of treatment depends on remaining growth