What is the appropriate evaluation and management for leg length discrepancy?

Evaluation and Management of Leg Length Discrepancy

For leg length discrepancies, measure in standing position using blocks and treat with shoe lifts when the discrepancy exceeds 1.0-1.5 cm, as smaller discrepancies rarely cause symptoms and do not require intervention. 1, 2

Initial Assessment

Measurement Technique

• Measure leg length in standing, weight-bearing position using blocks of adequate thickness under the shorter limb until the pelvis is level, assessing the position of the posterior superior iliac spine 3
• Standing radiographic measurements correlate highly with supine measurements, but standing position is preferred for functional assessment 4
• Physical examination measurements alone show weak correlation with radiographic measurements and should not be relied upon exclusively 4

Key Clinical Findings to Document

• Limb length difference (measure both apparent and true leg length) 5
• Alignment in coronal and sagittal planes 5
• Torsional profile 5
• Presence of compensatory mechanisms (pelvic obliquity, lumbar scoliosis with convexity toward shorter side) 3
• Associated symptoms: low back pain, hip pain, knee pain, or gait asymmetry 6, 3

Treatment Thresholds and Indications

Evidence-Based Cutoffs

• Discrepancies <1.5-2.0 cm typically do not require treatment, as patients generally do not consider these problematic and function well without intervention 2
• Discrepancies ≥1.0 cm warrant consideration for correction, particularly if symptomatic 3
• Discrepancies >5 cm may require surgical intervention during growing years 1

Clinical Context Matters

• 7% of asymptomatic individuals have discrepancies >12 mm 6
• The incidence rises to 13-22% in patients with low back pain 6
• Individual variation is substantial—some patients function well athletically with discrepancies >2.5 cm 2

Conservative Management

Shoe Lift Prescription

• Start with external shoe lifts for discrepancies 1.0-2.0 cm 3
• For larger discrepancies, consider internal shoe modifications or custom orthoses 1
• When using unilateral lifts, monitor for acquired contralateral problems—the International Working Group on the Diabetic Foot warns that long-term use can cause bilateral knee and hip complaints 7

Implementation Strategy

• Initial correction may take 2 weeks to 24 months for full spinal adjustment (mean 11.3 months) 3
• Expect correction of functional scoliosis in 83.7% of patients within 2 weeks of proper lift application 3
• 14.7% of patients experience transient mild low back pain during adjustment period 3
• Physical therapy to address compensatory mechanisms should accompany orthotic treatment 5

Important Caveat on Bilateral Devices

• If using a knee-high or ankle-high offloading device on one limb, add a compensatory lift to the contralateral shoe to prevent acquired limb-length discrepancy and maintain balance 7, 8
• For a 12 mm acquired discrepancy from orthotic devices, add approximately 6 mm to the opposite shoe to halve the discrepancy and reduce bilateral mechanical stress 7

Surgical Management (Pediatric Patients)

Timing and Techniques

• Evaluate skeletal maturity and remaining growth potential using predictive algorithms (accurate to within 2 cm) 1
• Guided growth techniques (epiphysiodesis) may be considered if growth plates remain open 5
• For predicted discrepancies >5 cm, consider leg-lengthening procedures during growing years 1
• Surgical options include epiphyseal plate blockade around the knee or osteotomy with distraction 1

Surgical Considerations

• Changes in leg length exert marked mechanical stress on soft tissues 1
• Treatment decisions are always elective and must be individualized based on functional impact, not solely on measured discrepancy 1

Monitoring and Follow-Up

Essential Surveillance

• Regular follow-up is mandatory to assess intervention effectiveness and monitor for secondary complications including musculoskeletal knee or hip complaints 7, 5
• Reassess alignment, gait pattern, and symptom resolution at each visit 5
• For pediatric patients, monitor for development of bone deformities and progression of discrepancy 9

Specialist Referral

• Refer patients with significant limb deformities to an orthopedic surgeon experienced in metabolic bone disease 5
• Complex cases requiring surgical intervention need subspecialty evaluation 1

Long-Term Outcomes

Expected Benefits

• Shoe modification can result in dramatic pain relief 6
• Correction eliminates functional scoliosis in the majority of cases 3
• Treatment is cost-effective compared to chronic pain management 6

Potential Complications Without Treatment

• Unequalized discrepancies lead to posture deformation, gait asymmetry, low back pain, and disc disease 3
• Mildly elevated incidence of knee osteoarthritis (though direct connection to back pain remains questionable) 1
• Hip osteoarthritis risk increases with untreated discrepancy 6