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.