Bipolar Hemiarthroplasty via Lateral Approach

Indications

• Displaced femoral neck fracture (Garden III/IV) in the elderly
• Pathological fracture of the femoral neck
• Failed internal fixation of femoral neck fracture

Patient Positioning

Step-by-Step Technique

Step 1 - Skin Incision

• Make a straight lateral incision centered over the tip of the greater trochanter, extending approximately 10-15 cm - roughly 5 cm proximally and 10 cm distally along the line of the femoral shaft.
• The incision is centered on the greater trochanter.

Skin incision for the lateral approach to the hip - Campbell's Operative Orthopaedics, 15th Ed.

Step 2 - Fascia Lata and IT Band

• Divide the iliotibial band (fascia lata) in line with the skin incision.
• Expose the greater trochanter and the musculature overlying it.

Step 3 - Gluteus Medius / Abductor Sleeve (Hardinge Release)

• Release the anterior one-third of the gluteus medius, the underlying gluteus minimus, the abductor tendon, and the vastus lateralis distally - all in a continuous sleeve off the greater trochanter.
• This is done in an anterior-to-posterior direction, keeping the release to the anterior third only to avoid denervating the posterior abductors.
• Critical landmark: The superior gluteal nerve runs approximately 5 cm proximal to the tip of the greater trochanter. Dissection must not extend more than 3-4 cm proximal to the trochanteric tip to protect this nerve - injury causes permanent abductor weakness and Trendelenburg gait.

Deep dissection showing the tensor fasciae latae and gluteus medius after fascial incision - Campbell's Operative Orthopaedics, 15th Ed.

Step 4 - Capsulotomy

• Retract the abductor sleeve anteriorly.
• Incise the hip joint capsule longitudinally along the anterosuperior surface of the femoral neck.
• Place retractors around the femoral neck to expose the fracture site.
• The origin of the vastus lateralis may be reflected distally or split longitudinally to expose the base of the trochanter and proximal femoral shaft.

Step 5 - Femoral Head Dislocation and Removal

• With the hip in flexion, adduction, and external rotation, lever the femoral head out of the acetabulum.
• Use a corkscrew device inserted into the femoral head to assist extraction.
• Remove the femoral head and measure its diameter - this determines prosthetic head sizing.

Step 6 - Femoral Neck Osteotomy

• If the fracture plane has not already defined the cut, perform a femoral neck osteotomy at the appropriate level (typically 1-1.5 cm above the lesser trochanter, at a 135-140° angle).
• Use the template or the excised femoral head as a guide to plan the cut level and version.
• Remove all fragments of the femoral head and neck from the acetabulum.

Step 7 - Acetabular Assessment

• Inspect the acetabular cartilage. In hemiarthroplasty, the acetabulum is not replaced - it must have intact cartilage to articulate with the bipolar prosthesis.
• Remove any osteophytes or debris. Confirm the labrum is intact.

Step 8 - Femoral Canal Preparation

• Open the femoral canal at the piriform fossa using a box chisel or awl.
• Broach sequentially in increasing sizes, maintaining neutral anteversion (approximately 10-15°). Each broach should be seated in the same version and alignment before proceeding to the next size.
• Avoid varus malpositioning (a common error with the lateral approach).
• Once the broach fits firmly (cortical chatter, no further advancement with mallet), select the final stem size.
• For cemented fixation: use a cement restrictor, lavage and dry the canal, pressurize bone cement, and insert the stem in correct version. Hold until cement sets.
• For uncemented (press-fit) fixation: impaction of the final stem directly.

Step 9 - Trial Reduction and Head Sizing

• Attach a trial femoral head (matching the excised head diameter - typically 40-54 mm for bipolar).
• Reduce the hip and assess:
  • Stability through a range of motion (flexion, internal rotation, adduction)
  • Leg length - use intraoperative landmarks (lesser trochanter level, longitudinal tension)
  • Offset - adequate soft tissue tension without impingement
• The bipolar head consists of an inner bearing (metal head articulating with a polyethylene-lined outer cup) that then articulates with the native acetabulum - providing two points of motion and reducing acetabular erosion compared to a unipolar prosthesis.

Step 10 - Final Component Assembly and Reduction

• Once satisfied with trial, remove the trial and attach the definitive femoral head and assemble the bipolar cup.
• Reduce the hip under direct vision. Confirm stability, leg length, and range of motion.

Step 11 - Wound Closure

• Repair the abductor sleeve (gluteus medius / minimus and vastus lateralis) firmly back to the greater trochanter using strong non-absorbable sutures (e.g., No. 5 Ethibond) through bone tunnels or transosseous sutures. This is the most important step for restoring abductor function.
• Close the iliotibial band.
• Close subcutaneous tissue and skin in layers.
• Insert a drain if desired.

Key Advantages of the Lateral Approach for Hemiarthroplasty

Postoperative Care

• Weight bearing as tolerated from day 1 (most cases)
• Hip precautions are less restrictive than posterior approach (no posterior dislocation precautions needed)
• Abductor strengthening physiotherapy
• DVT prophylaxis