What is the surgical procedure for bipolar hemiarthroplasty?

Surgical Procedure for Bipolar Hemiarthroplasty

Bipolar hemiarthroplasty should be performed through a posterior approach with meticulous technique focusing on femoral canal preparation, cemented stem fixation, and capsular repair to minimize complications including bone cement implantation syndrome (BCIS), dislocation, and periprosthetic fracture. 1, 2

Pre-operative Preparation

Anesthesia Selection

• Either spinal or general anesthesia is appropriate, though spinal anesthesia may reduce postoperative confusion in elderly patients 1, 2
• Administer multimodal analgesia incorporating a preoperative femoral nerve block for optimal pain control 2
• Administer tranexamic acid at the start of the procedure to reduce blood loss and transfusion requirements 1

Patient Positioning

• Position the patient in lateral decubitus with proper padding of bony prominences to prevent pressure injuries 1

Surgical Approach and Exposure

Posterior Approach Technique

• Split the gluteus maximus muscle in the direction of muscle fibers to minimize damage 1
• Identify and protect the sciatic nerve throughout the procedure 1
• Incise the posterior capsule and short external rotators for exposure 2

Femoral Neck Osteotomy

Osteotomy Technique

• Perform femoral neck osteotomy at the base of the femoral neck using an oscillating saw 2
• For unstable intertrochanteric fractures, a two-step osteotomy technique may be employed with the first osteotomy at the base of the femoral neck 1, 3
• Remove the femoral head and expose the femoral canal, removing any fracture debris 1

Femoral Canal Preparation (Critical for BCIS Prevention)

Communication Protocol

• The surgeon must verbally announce to the anesthesiologist before instrumenting the femoral canal, and the anesthesiologist must confirm awareness 4

Canal Preparation Steps

• Use sequential reamers or broaches starting with smaller sizes and progressively increasing 2
• Use a pressurized lavage system to clean the endosteal bone of fat and marrow contents 4, 5
• Carefully prepare, wash, and thoroughly dry the femoral canal 4, 1
• Place a distal intramedullary plug at the appropriate depth 4, 1
• Use a distal suction catheter on top of the intramedullary plug 4

Trial Reduction

• Perform trial reduction with provisional implants to assess stability, leg length, and offset 1

Cement Application and Stem Insertion (Cemented Technique Recommended)

Cemented Stem Rationale

• Cemented femoral stems are recommended for elderly patients with osteoporosis, as they reduce reoperation risk and are associated with lower 30-day mortality 1, 2, 6
• Uncemented stems have a 1.5 times higher risk of reoperation, primarily due to periprosthetic femoral fractures 6

Cement Insertion Technique

• Insert cement from a gun in retrograde fashion on top of the plug 4, 5
• Pull the suction catheter out as soon as it is blocked with cement 4, 5
• Do NOT use excessive manual pressurization or pressurization devices in patients at higher risk of cardiovascular events (elderly, male sex, significant cardiopulmonary disease, diuretic use) 4, 5
• Insert the final femoral stem with 5-10 degrees of anteversion 1, 2
• Hold the stem in position until cement hardens 1

Prosthesis Assembly and Reduction

Bipolar Head Assembly

• Assemble the bipolar prosthesis by placing the appropriate-sized bipolar head onto the femoral stem 2
• The bipolar head consists of a steel outer shell and polyethylene liner with an inner steel head that moves inside 7

Hip Reduction

• Reduce the hip by gentle traction and internal rotation 1
• Test range of motion and stability to ensure no impingement or dislocation 1
• Properly tension the abductor mechanism to ensure stability and prevent dislocation 1

Closure and Capsular Repair

Soft Tissue Repair

• Repair the posterior capsule and short external rotators to reduce dislocation risk 1, 2
• Close the wound in layers and apply a sterile dressing 1

Anesthetic Management During Critical Phases

Hemodynamic Monitoring

• Ensure adequate hydration before induction and during anesthesia 4, 5
• Maintain systolic blood pressure within 20% of pre-induction values throughout surgery using vasopressors and/or fluids 4, 5
• Use invasive blood pressure monitoring for patients at higher risk 4
• Have vasopressors (metaraminol/adrenaline) ready for cardiovascular collapse 4
• Increase inspired oxygen concentration during critical moments of femoral canal preparation 5

Post-operative Management

Immediate Care

• Administer supplemental oxygen for at least 24 hours postoperatively 5
• Continue active warming strategies to prevent hypothermia 2
• Administer fondaparinux or low molecular weight heparin for DVT prophylaxis 2

Mobilization

• Begin physical therapy on postoperative day one if medically stable 2
• Implement early mobilization protocols with weight-bearing as tolerated 2

Critical Complications and Prevention

Bone Cement Implantation Syndrome (BCIS)

• Adverse cardiovascular events occur in approximately 20% of cemented hemiarthroplasty cases 4
• Grade 1 (oxygen saturation <94% or >20% fall in systolic BP) occurs in ~20% of cases 4
• Grade 2 (oxygen saturation <88% or >40% fall in systolic BP or loss of consciousness) occurs in ~3% 4
• Grade 3 (cardiopulmonary resuscitation required) occurs in ~1% 4
• Risk factors include increasing age, male sex, significant cardiopulmonary disease, and diuretic medication use 4

Dislocation Prevention

• The anterolateral transgluteal approach has a 30% lower risk of reoperation due to dislocation compared to posterior approach (HR = 0.7) 6
• However, meticulous capsular repair with posterior approach can achieve comparable stability 1, 2

Infection Prevention

• Use meticulous sterile technique and appropriate perioperative antibiotics 1
• Postoperative infections are the most common complication (3.1% of all cases) 8

Implant Selection Considerations

• Unipolar implants should be preferred over bipolar for the oldest and frailest patients 6
• Bipolar implants have a 1.3 times higher risk of reoperation regardless of cause, including higher rates of dislocation (1.4×), infection (1.3×), and periprosthetic fracture (1.7×) 6
• However, bipolar implants have better stability and lower risk of acetabular protrusion than unipolar designs 7