Should a patient with a 1.76 cm leg length discrepancy on computed tomography (CT) scan be referred to orthopedic (ortho) service?

Management of Leg Length Discrepancy of 1.76 cm

Referral to orthopedic services is recommended for a patient with a 1.76 cm leg length discrepancy confirmed by CT scan, as this discrepancy exceeds the threshold that can lead to long-term pathology and may require specialized intervention. 1

Clinical Significance of Leg Length Discrepancy (LLD)

• Leg length discrepancies greater than 5 mm can lead to long-term pathology including hip and knee problems, with discrepancies over 2.0 cm frequently causing significant issues 1
• A discrepancy of 1.76 cm falls into the range where intervention should be considered, as it may cause:
  • Increased risk of hip pathology (more common in the longer leg) 1
  • Increased risk of knee pathology 1
  • Low back problems (more common on the shorter side) 1
  • Altered gait mechanics and compensatory mechanisms 1

Assessment Considerations

• CT scan is a reliable method for measuring leg length discrepancy, with high interobserver reliability when using standard anatomical landmarks 2
• The discrepancy should be evaluated in the context of:
  • Presence of symptoms (pain, gait abnormality, functional limitations) 3
  • Impact on quality of life and daily activities 3
  • Age of the patient and skeletal maturity 4

Treatment Algorithm

For a 1.76 cm LLD:

1. Initial Orthopedic Evaluation

   • Patients with significant limb deformities should be evaluated by an orthopedic surgeon with experience in metabolic bone disease 4
   • Assessment should include limb length, alignment in coronal and sagittal planes, and torsional profile 4

2. Treatment Options

   • Conservative Management:

     • Shoe lift or orthosis to compensate for the discrepancy 3
     • Physical therapy to address any compensatory mechanisms 4
     • Emphasis on weight-bearing exercise, maintenance of joint range, and maximizing strength 4

   • Surgical Considerations:

     • For pediatric patients: guided growth techniques may be considered if growth plates are still open 4
     • For adults or skeletally mature patients: surgical intervention may be considered if the discrepancy causes significant functional limitations or pain 3

Clinical Pearls and Pitfalls

• Important Caveat: The decision to treat is always elective and should consider multiple factors beyond just the numerical measurement of discrepancy 3
• Avoid Common Pitfall: Don't assume that all leg length discrepancies require surgical correction; many can be managed conservatively with shoe modifications 3
• Key Consideration: When using shoe lifts, be aware that an acquired limb-length discrepancy from orthotic devices can lead to musculoskeletal knee or hip complaints 4
• Monitoring Recommendation: Regular follow-up is essential to assess the effectiveness of intervention and to monitor for development of secondary complications 4

Conclusion for Clinical Practice

The 1.76 cm leg length discrepancy detected on CT scan warrants orthopedic referral for comprehensive evaluation and management planning. While this discrepancy exceeds the 5 mm threshold associated with pathology, treatment should be tailored based on symptoms, functional impact, and patient factors rather than the numerical value alone.