TKA continued

Patella-Femoral Arthroplasty (PFA)

Indications

  1. Isolated patellofemoral (PF) arthritis.
  2. Young patients (<50 years).

Contraindications

  1. PF instability.
  2. Medial or lateral compartment arthrosis.
  3. High-demand patients with unrealistic expectations.
  4. Inflammatory arthritis.
  5. Malalignment.

Results

  1. Appropriate Patients:
    • 90% good outcomes at mid-term follow-up.
  2. Conversion to TKR:
    • Outcomes may be worse compared to primary TKR.
    • Early studies (e.g., AAOS 2012) report mixed results.

Management of Bone Deficiency in TKR

Causes

  • Bone loss may occur due to various etiologies, including degenerative changes or previous surgeries.

Classification of Bone Defects

  1. Type 1:
    • Small, focal defect contained within cortical rim.
  2. Type 2:
    • Larger metaphyseal defect, still contained within cortical rim.
  3. Type 3:
    • Uncontained metaphyseal defect with no cortical rim.

Management Strategies

  1. Contained Defects <5 mm:
    • Fill with cement.
  2. Larger Contained Defects:
    • Use impacted cancellous graft.
  3. Very Large or Uncontained Defects:
    • Structural autograft fixed with screws.
    • Cement around multiple screws.
    • Metallic augments.
  4. Critical Considerations:
    • Ensure correct alignment to avoid stress on grafts.
    • For significant grafting, use stems to dissipate stress away from the graft.

Wound Closure

Key Steps

  1. Perform closure in flexion:
    • Ensures patella tracking.
    • Avoids soft tissue restriction impacting ROM.
  2. Use sub-cuticular sutures:
    • Minimizes wound ooze.

Use of Drains

Observations

  1. No significant difference in wound infection rates.
  2. With Drains:
    • Increased risk of transfusions.
  3. Without Drains:
    • Requires more dressing changes and padding but no increase in infection rates.
    • Note: Avoiding wound drainage is preferable to minimize infection risk.

Use of Navigation in TKR

Benefits

  1. Ideal for managing pre-operative femoral or tibial deformities.
  2. Improves consistency in recreating correct mechanical axes in primary TKR.

Limitations

  • Improved alignment has not yet been directly correlated with better clinical outcomes.

Custom Cutting Blocks

Overview

  1. Useful for challenging primary or revision knees.
  2. Process:
    • Pre-operative MRI or CT used for templating.
    • Cutting blocks are custom-made for patient anatomy.
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