What are the considerations for choosing between hemiepiphysiodesis (temporary halt of growth plate growth) of the distal femur or proximal tibia for deformity correction in a child?

Considerations for Choosing Between Distal Femur or Proximal Tibia Hemiepiphysiodesis for Deformity Correction

Distal femoral hemiepiphysiodesis is generally preferred over proximal tibial hemiepiphysiodesis for most coronal plane deformities due to fewer complications and more predictable correction rates. 1, 2

Anatomical Considerations

• Growth Potential:

  • Distal femur contributes approximately 70% of growth around the knee
  • Proximal tibia contributes approximately 30% of growth around the knee
  • This difference results in faster correction rates at the distal femur

• Mechanical Axis Effects:

  • Proximal tibial hemiepiphysiodesis leads to significantly larger shifts in the mechanical axis compared to distal femoral procedures 3
  • Tibial procedures have higher risk of overcorrection and secondary deformities

Deformity-Specific Recommendations

For Genu Valgum (Knock-Knees):

• First choice: Distal femoral medial hemiepiphysiodesis

  • More predictable correction rate (0.59° per month) 4
  • Lower complication rate
  • Less risk of mechanical axis deviation

• Second choice: Combined distal femoral and proximal tibial medial hemiepiphysiodesis

  • Consider for severe deformities requiring faster correction
  • Requires more vigilant follow-up to prevent overcorrection

For Genu Varum (Bow-Legs):

• First choice: Distal femoral lateral hemiepiphysiodesis

  • More predictable correction
  • Lower risk of mechanical axis deviation

• Second choice: Proximal tibial lateral hemiepiphysiodesis

  • Higher correction rate (0.85° per month vs 0.15° per month for distal femur) 4
  • Higher risk of complications including stress fractures 5
  • Consider for cases with predominant tibial deformity

Timing Considerations

• Guided growth techniques must be performed at least 2-3 years before skeletal maturity (age 14 in girls, age 16 in boys) 1
• Correction rate depends on remaining growth potential
• Younger patients have greater correction potential but higher risk of recurrence

Complication Risks

Distal Femur Complications:

• Lower risk of mechanical axis deviation
• Lower risk of stress fractures
• Potential for overcorrection if plates left in situ too long

Proximal Tibia Complications:

• Higher risk of mechanical axis deviation (89% of shifts are varus in nature) 3
• Higher risk of stress fractures 5
• 6 times higher risk of requiring subsequent osteotomy to correct secondary deformities 3
• Inadequate staple/plate placement more common in proximal-lateral tibia 3

Follow-Up Protocol

• Regular clinical and radiographic assessments should be performed at least every 3-6 months
• Radiographic assessment at 12 months post-surgery is essential 1
• Earlier assessment if clinical concern or worsening deformity
• Continue follow-up until skeletal maturity

Special Considerations

• For sagittal plane deformities (e.g., knee flexion contractures), anterior distal femoral hemiepiphysiodesis has shown good results 6
• In skeletal dysplasias like achondroplasia, both locations can be effective, with 81% achieving correction to zone 1 mechanical axis 7

Decision Algorithm

1. Assess primary location of deformity (femoral vs tibial)

2. Consider remaining growth potential (age and skeletal maturity)

3. For most cases, start with distal femoral hemiepiphysiodesis

4. Reserve proximal tibial hemiepiphysiodesis for:

   • Predominant tibial deformity
   • Need for rapid correction (with close monitoring)
   • Cases where distal femoral growth plate is compromised

5. Consider combined approach only for severe deformities requiring rapid correction

Remember that persisting deformity (mechanical axis deviation Zone 2 or greater) despite optimized medical treatment should be considered for surgical intervention 1.