What it is

Leg length discrepancy refers to a difference in limb length between sides. Structural differences arise from bone length; functional differences arise from pelvic mechanics or muscle tightness.

Small differences are common and usually harmless. Larger or symptomatic differences can alter gait and load on the hip, pelvis, and spine.

What happens when it occurs

Persistent asymmetry can change step length, pelvic tilt, and ground reaction force patterns. Sensitive tissues may complain until loads are balanced.

Common causes and risk factors

  • Previous fractures or growth-plate injuries
  • Hip or knee surgery, joint degeneration, or congenital differences
  • Pelvic tilt from muscle imbalance or capsular stiffness

Who is most affected

Adults with prior injuries, adolescents following growth spurts, and post-surgical patients.

Typical symptoms

  • Low back, hip, or knee aching after long walks or runs
  • Unilateral soreness with hills or stairs
  • Noticeable shoe wear differences

When to seek care

Seek assessment when symptoms persist, training stalls, or asymmetry is obvious in photos or shoe wear.

How we diagnose

History, functional testing, and tape or block testing in clinic to estimate discrepancy. Imaging measures true limb length when needed.

Management

  • Targeted mobility and strength to address functional components
  • Trial of shoe insert or heel lift for structural differences
  • Gait coaching and graded exposure to walking and running

Rehabilitation milestones

Phase 1 weeks 0 to 2: pain control, identify functional drivers, begin mobility.

Phase 2 weeks 2 to 6: progressive strength and lift trial, walking plan.

Phase 3 weeks 6 to 12: running or hiking progressions, hills and stairs.

Phase 4 weeks 12 to 16: performance and workload targets.

Readiness to progress

  • Comfortable walking distance with even step length
  • Hip and trunk strength within 90 percent
  • No next-day flare after hills or stairs

Prevention

  • Maintain hip and trunk strength
  • Use gradual hiking and running progressions
  • Replace worn shoes before stability declines

Australia snapshot

  • Common in post-surgical and post-fracture groups
  • Many runners present with small, manageable differences
  • Lift trials are widely available through clinics and retailers

Latest insights

Treat the person, not the tape measure. Many small differences need no correction.

When a lift helps, adjust it in steps and retest walking, hills, and running.

Frequently Asked Questions

It depends on symptoms and tasks. Many small differences are well tolerated and need no correction.

Trial a small lift and reassess walking and running. Increase only if it improves comfort and control.

They can resolve functional components and improve tolerance. Structural differences often benefit from both exercise and footwear changes.

Loads change with asymmetry. Strength and pacing reduce symptoms and protect the back and hips.

Build distance gradually, add hills late, and rotate shoes with similar stack height.

Only when the amount needs confirmation or surgery is being planned.

Expect two to six weeks to settle with a new lift or programme.