High Tibial Osteotomy

Clinical Indications

  • Varus malalignment with:
    1. Medial compartment osteoarthritis (OA) and pain
    2. Instability
      • Alteration of the slope can compensate for anterior or posterior translation in ACL or PCL deficient knee
    3. Protection of chondral or meniscal surgery
      • Restoration of mechanical axis maintains longevity of the soft tissue procedure

Contraindications

  1. Absolute:
    • Patellofemoral OA
    • Tricompartmental OA
    • Fixed flexion contracture >10 degrees
    • Fixed varus or valgus contracture >10 degrees
    • Lateral tibial subluxation >1cm
  2. Relative:
    • Poor range of motion (ROM) (<90 degrees flexion)
    • Smoker
    • Inflammatory arthropathy
    • Varus thrust on walking

Ideal Patient

  1. Young
  2. Non-smoker
  3. Correctible deformity
  4. Isolated medial OA

Surgical Techniques

Traditionally Closing Lateral Wedge

  • Disadvantages:
    1. Patella baja
    2. Altered slope
    3. More challenging total knee replacement (TKR)
    4. Peroneal nerve palsy
    5. Loss of bone stock

Medial Opening Wedge

  • Disadvantages:
    1. Non-union
    2. Risk of collapse or fixation loss
  • Advantages:
    1. Retention of slope and bone stock
    2. Easier TKR
    3. No patella baja
  • Outcome:
    • No high-quality trials indicate superiority of one technique over the other.

Alternative Techniques

Dome Osteotomy

  • Description: Done above the tibial tubercle.
  • Indication: Useful for big, multiplanar correction.
  • Advantages: Does not alter patella height.
  • Disadvantages: Technically difficult.

Distraction Osteogenesis Technique

  • Indication: For very large corrections using the Taylor Spatial Frame (TSF) for gradual distraction.

Pre-Operative Planning

History

  • Determine if pain is acute or insidious.
  • Rule out meniscal tear vs arthrosis.
  • Assess symptoms like instability, locking, or catching.
  • Consider smoking history.

Examination

  • Overall alignment.
  • Check for concurrent patella instability and consider tubercle transfer if necessary.
  • Assess knee stability.
  • Identify the point of pain.

Investigations

  1. Simple AP, lateral, and skyline X-rays of the knee standing.
  2. Long leg standing alignment X-rays.
  3. MRI.
  4. Arthroscopic evaluation pre-operatively.

Osteotomy Planning

  1. Long leg AP views are essential for planning.
  2. Mark the mechanical axis of the leg – from the center of the femoral head to the center of the ankle.
    • The axis should pass just lateral to the middle of the tibial plateau.
    • If the line passes more medially, the knee is in varus; if more laterally, the knee is in valgus.
  3. Osteotomy Angle:
    • Aim for slight overcorrection to valgus.
    • Calculate the angle between the two lines (femoral head to the desired axis and ankle to the same point) for correction.
  4. Opening Wedge Height:
    • Draw a line from 4cm distal to the medial joint line to just proximal to the fibula head (this is the osteotomy cut plane).
    • Measure the distance from the subtended line to the femoral mechanical axis line to determine how much the osteotomy needs to be opened for angular correction.

Post-Operative Management

  • ROM exercises.
  • Touch-weight bearing (TWB) for 6 weeks (6/52).

Outcomes

  • Conversion to TKR vs Primary TKR:
    • High tibial osteotomy may have longer surgical time, less mean ROM, and is technically more demanding, but clinical outcomes do not correlate with these factors.
  • Closing vs Opening Wedge:
    • No long-term outcome difference between closing and opening wedge techniques, though theoretical benefits of the opening wedge are widely accepted today.
  • Overall:
    • High tibial osteotomy provides good long-term results, with a mean follow-up of 10 years in some studies, maintaining activity levels and pain relief.
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