Anterolateral approach to the hip

Introduction

Indications

• Total hip replacement / hemiarthroplasty.
• Open reduction and internal fixation of femoral neck fractures.
• Synovial biopsy of the hip / biopsy of the femoral neck.

Advantage

• Excellent exposure of the acetabulum with safety during reaming of the femoral shaft.

Position of patient

• The patient is placed in a lateral decubitus position, and the limb draped so that it can be moved during surgery.

Landmarks and incision

Landmarks

• The anterior superior iliac spine is felt subcutaneously by bringing the thumbs up from beneath the bony protuberance.
• The greater trochanter is a large mass of bone that projects up and back from the junction of the shaft of the femur and its neck.
• The shaft of the femur can be felt as a resistance through the vastus lateralis.
• The vastus lateralis ridge, a rough line that marks the fusion site of the greater trochanter to the lateral surface of the shaft of the femur, is easiest to palpate from distal to proximal.

Incision

• A 15-cm straight longitudinal incision centered on the tip of the greater trochanter, crosses the posterior third of the trochanter before running down the shaft of the femur.

Internervous plane

• No true internervous plane for this approach because the gluteus medius and the tensor fasciae latae have a common nerve supply, the superior gluteal nerve.

Superficial dissection

• Incise the fat in the line of the skin, reaching the deep fascia of the thigh.
• Gently push subcutaneous fat off the fascia lata using a sponge until reaching the fascia at the posterior margin of the greater trochanter.
• Incise the fascia lata, entering the bursa that underlies it. Divide in the line of its fibers superiorly, heading proximally and anteriorly in the direction of the anterior superior iliac spine and extending the cut distally and slightly anteriorly to expose the underlying vastus lateralis muscle.This flap is elevated anteriorly.
• Detach the few fibers of the gluteus medius that arise from the deep surface of this fascial flap and identify the interval between the tensor fasciae latae and the gluteus medius.
• A series of vessels cross the interval between the tensor fasciae latae and the gluteus medius. These act as a guide to the interval, but require ligation.
• Fully rotate the hip externally to put the capsule on stretch.

Deep dissection

• Identify and incise the origin of the vastus lateralis at the vastus lateralis ridge using a cautery knife. Reflect the muscle inferiorly for about 1 cm.
• Bluntly dissect the anterior part of the joint capsule, lifting off the fat pad that covers it.
• Two techniques improve exposure of the acetabulum by neutralizing the abductor mechanism, allowing the femur to fall posteriorly and adduction of the leg for safe femoral reaming and accurate positioning of prosthetic stems within the femoral shaft.
  1. Trochanteric osteotomy
  a. Allows complete mobilization of the gluteus medius and minimus muscles.
  b. Osteotomize the trochanter using either an oscillating saw or a Gigli saw, and then reflect it upward with the attached gluteus medius and minimus muscles.
  c. The base of the osteotomy should be at the base of the vastus lateralis ridge and the upper end of the osteotomy may be either intracapsular or extracapsular.
  2. Partial detachment of the abductor mechanism
  a. Cut the insertion of this anterior portion off the trochanter.
  b. Identify the thick white tendon of the gluteus minimus as it inserts onto the anterior aspect of the trochanter and incise it.
• Bluntly dissect the anterior surface of the hip joint capsule in line with the femoral neck and head.
• Detach the reflected head of the rectus femoris and part of the psoas tendon from the joint capsule to expose the anterior rim of the acetabulum.
• Incise the anterior capsule of the hip joint into a T shape.
• Dislocate the hip by externally rotating it after an adequate capsulotomy has been performed.

Dangers

Femoral nerve

• The most common problem is compression neurapraxia, caused by overexuberant medial retraction of the anterior covering structures of the hip joint.

Femoral artery and vein

• In danger by incorrectly placed acetabular retractors that penetrate the iliopsoas, piercing the vessels as they lie on the surface of the muscle.

Fractures of the femoral shaft

• Femoral shafts have been known to fracture while hips are being dislocated. For that reason, it is critical to do an adequate capsular release before attempting dislocation.

How to enlarge the approach

Distally to expose the entire length of the femur

• Extend the skin incision down the lateral aspect of the thigh. Incise the deep fascia in line with the skin incision and split the vastus lateralis to gain access to the lateral aspect of the femur.

Proximally

• Approach cannot be usefully extended.

Figures