What is the step by step procedure for Bipolar Hemiarthroplasty?

Step-by-Step Procedure for Bipolar Hemiarthroplasty

Bipolar hemiarthroplasty is a surgical procedure that involves replacing the femoral head with a prosthesis that has both an inner bearing and an outer shell, while preserving the patient's acetabulum. This procedure is commonly performed for unstable (displaced) femoral neck fractures in elderly patients.

Preoperative Preparation

• Timing: Surgery should be performed within 24-48 hours of admission to reduce complications and mortality 1
• Anesthesia options: Either spinal or general anesthesia is appropriate (strong recommendation) 1
• Preoperative planning:
  • Avoid preoperative traction 1
  • Obtain standard radiographs (AP pelvis and lateral hip views)
  • Ensure adequate hydration before induction of anesthesia 1
  • Prepare for potential bone cement implantation syndrome (BCIS) if using cemented technique 1

Surgical Approach

• Either anterolateral or posterior approach can be used
  • Anterolateral approach has lower risk of dislocation (HR = 0.7) 2
  • Modified posterior approach with preservation of short external rotators can reduce dislocation risk in patients with neurological disorders 3
  • Direct anterior approach may allow earlier mobilization and reduced postoperative pain 4

Step-by-Step Surgical Procedure

1. Patient positioning:

   • Lateral decubitus position for posterior or anterolateral approach
   • Supine position for direct anterior approach

2. Incision and approach:

   • Make skin incision according to chosen approach
   • Dissect through subcutaneous tissue
   • Identify and protect neurovascular structures
   • Access the hip joint through the selected approach

3. Femoral neck osteotomy:

   • Expose the femoral neck
   • Perform osteotomy at the appropriate level
   • Remove the femoral head

4. Acetabular assessment:

   • Inspect the acetabulum for damage
   • Confirm intact articular surface suitable for hemiarthroplasty

5. Femoral canal preparation:

   • Communication with anesthesia team: Surgeon must inform the anesthetist before preparing the femoral canal for cement and prosthesis insertion 1
   • Open the femoral canal
   • Thoroughly wash and dry the femoral canal
   • Use a pressurized lavage system to clean the endosteal bone of fat and marrow contents 1

6. Cement application (for cemented technique - strongly recommended):

   • Place an intramedullary plug in the femoral shaft
   • Insert a distal suction catheter on top of the plug
   • Apply cement in retrograde fashion using the cement gun
   • Pull the catheter out as soon as it is blocked with cement
   • Avoid excessive manual pressurization in high-risk patients 1

7. Prosthesis insertion:

   • Insert the femoral stem
   • Attach the appropriate neck length
   • Assemble the bipolar head (inner bearing and outer shell)
   • Place the bipolar head onto the femoral neck

8. Reduction and stability testing:

   • Reduce the hip joint
   • Test for stability through range of motion
   • Ensure appropriate leg length and offset

9. Enhanced soft tissue repair:

   • Implement soft tissue repair with locking loop stitches to minimize dislocation risk 5
   • Reattach any detached muscles or tendons
   • Close the wound in layers

Anesthesia Considerations During Cement Application

• Maintain vigilance for signs of cardiorespiratory compromise 1
• Use either an arterial line or non-invasive automated blood pressure monitoring set on 'stat' mode during/shortly after cement application 1
• Aim to maintain systolic blood pressure within 20% of pre-induction values 1
• Be prepared to administer vasopressors (e.g., metaraminol/adrenaline) in case of cardiovascular collapse 1

Postoperative Care

• Begin physical therapy on postoperative day 1 5
• Implement an interdisciplinary care program to improve outcomes 5
• Progress from assisted to independent ambulation based on patient ability
• Follow-up at 2-4 weeks, then at 3 months, 6 months, and annually 5
• Obtain radiographic evaluation to assess component position and potential complications

Potential Complications and Prevention

• Dislocation: Use appropriate surgical approach (anterolateral has lower dislocation risk) 2
• Infection: Administer appropriate perioperative antibiotics
• Periprosthetic fracture: Higher risk with uncemented stems (HR = 1.5) 2
• Bone cement implantation syndrome: Follow recommended cement application techniques 1
• Acetabular erosion: Risk is lower with bipolar compared to unipolar implants (HR = 0.30) 2

Implant Selection

• Cemented femoral stems are strongly recommended 1, 5
• Either unipolar or bipolar hemiarthroplasty can be equally beneficial (moderate recommendation) 1
• Bipolar hemiarthroplasty provides good long-term survivorship with a 20-year cumulative incidence of revision for any reason of only 3.5% 6

Bipolar hemiarthroplasty is an effective treatment option for displaced femoral neck fractures in elderly patients, offering good stability and lower risk of acetabular protrusion compared to unipolar hemiarthroplasty 7.