What is the step-by-step procedure for a patient with a false acetabulum undergoing total hip replacement with Greater Trochanteric (GT) osteotomy?

Total Hip Replacement with Greater Trochanteric Osteotomy for False Acetabulum: Step-by-Step Procedure

Total hip replacement with greater trochanteric osteotomy is the optimal surgical approach for patients with a false acetabulum, as it provides superior exposure and access to reconstruct the true acetabulum while preserving hip biomechanics.

Preoperative Planning

1. Imaging Assessment:

   • Obtain standard radiographs as the first-line imaging modality 1
   • Consider advanced imaging (CT/MRI) to assess:
     • Extent of acetabular bone deficiency
     • Location of false and true acetabulum
     • Quality of remaining bone stock

2. Component Selection:

   • Determine appropriate acetabular component based on defect size:
     • For defects >6-8 cm, total hip arthroplasty is indicated 1
     • Consider jumbo cup vs. structural allograft options based on bone deficiency 2

Surgical Procedure

Step 1: Patient Positioning and Approach

• Position patient in lateral decubitus position
• Prepare and drape the hip using standard sterile technique
• Make a posterolateral incision extending from the greater trochanter distally along the femoral shaft

Step 2: Greater Trochanteric Osteotomy

• Sliding trochanteric osteotomy technique is preferred as it:

  • Facilitates improved exposure 3
  • Allows for trochanteric advancement if needed 3
  • Provides resistance to trochanteric migration 4

• Osteotomy procedure:

  1. Identify the vastus ridge and plan osteotomy line
  2. Carefully elevate the posterior border of vastus lateralis to expose the osteotomy site 5
  3. Use an oscillating saw to create the osteotomy, starting at the tip of the greater trochanter and extending distally
  4. Maintain a fragment thickness of approximately 1-1.5 cm
  5. Reflect the osteotomized fragment anteriorly with attached abductor muscles

Step 3: Femoral Head Resection and Exposure

• Dislocate the hip joint
• Resect the femoral head at the appropriate level
• Place retractors to expose the false acetabulum

Step 4: Acetabular Preparation and Reconstruction

• Identify the true acetabulum (often located more medially and superiorly)
• Remove soft tissue and any fibrous tissue from the true acetabular region
• Begin reaming at the true acetabulum location
• Options for acetabular reconstruction:

  1. For moderate defects:

     • Ream the true acetabulum to appropriate size
     • Consider bone grafting of defects
     • Place appropriately sized acetabular component

  2. For severe defects with substantial bone loss:

     • Consider structural allograft to reconstruct the acetabulum 2
     • Use a posterior buttressing plate for any graft providing substantial posterior support 2
     • Alternatively, use a jumbo cup filling the expanded acetabulum 2

Step 5: Femoral Preparation and Component Insertion

• Prepare the femoral canal according to standard technique
• Size and insert the femoral component
• Perform trial reduction to assess stability, leg length, and offset

Step 6: Greater Trochanter Reattachment

• Reduce the greater trochanter to its anatomical position
• Secure with:
  • 1-2 cables along the diaphyseal segment of the osteotomy 5
  • Consider additional fixation with cerclage wires or cables
  • Ensure stable fixation while maintaining vascularity to the fragment

Step 7: Final Reduction and Closure

• Perform final reduction with definitive components
• Assess stability through range of motion
• Irrigate thoroughly
• Close in layers with attention to soft tissue repair
• Apply sterile dressing

Postoperative Management

1. Immediate Postoperative Care:

   • Maintain hip precautions
   • Initiate DVT prophylaxis
   • Begin gentle range of motion exercises

2. Weight-Bearing Protocol:

   • Protected weight-bearing (toe-touch or partial) for 6-8 weeks to allow trochanteric healing
   • Progress to full weight-bearing based on radiographic evidence of healing

3. Follow-up:

   • Regular radiographic assessment to monitor:
     • Trochanteric healing
     • Component position
     • Signs of loosening or migration

Potential Complications and Management

1. Trochanteric Nonunion:

   • Occurs in a small percentage of cases
   • May require revision fixation if symptomatic 4

2. Trochanteric Migration:

   • Usually preceded by nonunion 4
   • Can result in impaired abductor function and gait 4
   • Consider reattachment if severe and accompanied by pain or instability

3. Trochanteric Bursitis:

   • May develop due to prominent fixation devices 4
   • Consider local steroid injection or removal of hardware if symptomatic

4. Component Loosening:

   • Regular radiographic surveillance
   • Revision surgery if symptomatic

The success of this procedure depends on meticulous attention to surgical technique, particularly maintaining vascularity to the osteotomized fragment and achieving stable fixation of both the trochanter and the acetabular component.