The posterolateral approach is a modification of the posterior approaches described by Gibson and by Moore. The approach can be extended proximally by osteotomy of the greater trochanter with anterior dislocation of the hip (see section on trochanteric osteotomy). The approach can be extended distally to allow a posterolateral approach to the entire femoral shaft. We use the posterolateral approach for primary and revision total hip arthroplasty.
Exposure and Removal of the Femoral Head 
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With the patient firmly anchored in the straight lateral position, make a slightly curved incision centered over the greater trochanter. Begin the skin incision proximally at a point level with the anterior superior iliac spine along a line parallel to the posterior edge of the greater trochanter. Extend the incision distally to the center of the greater trochanter and along the course of the femoral shaft to a point 10 cm distal to the greater trochanter. Adequate extension of the upper portion of the incision is required for reaming of the femoral canal from a superior direction, and the distal extent of the exposure is required for preparation and insertion of the acetabular component from an anteroinferior direction ( Figure 2-1 ).
Figure 2-1
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Divide the subcutaneous tissues along the skin incision in a single plane down to the fascia lata and the thin fascia covering the gluteus maximus superiorly.
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Dissect the subcutaneous tissues from the fascial plane for approximately 1 cm anteriorly and posteriorly to make identification of this plane easier at the time of closure.
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Divide the fascia in line with the skin wound over the center of the greater trochanter.
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Bluntly split the gluteus maximus proximally in the direction of its fibers, and coagulate any vessels within the substance of the muscle.
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Extend the fascial incision distally far enough to expose the tendinous insertion of the gluteus maximus on the posterior femur.
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Bluntly dissect the anterior and posterior edges of the fascia from any underlying fibers of the gluteus medius that insert into the undersurface of this fascia. Suture moist towels or laparotomy sponges to the fascial edges anteriorly and posteriorly to exclude the skin, prevent desiccation of the subcutaneous tissues, and collect cement and bone debris generated during the operation.
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Insert a Charnley or similar large self-retaining retractor beneath the fascia lata at the level of the trochanter. Take care not to entrap the sciatic nerve beneath the retractor posteriorly.
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Divide the trochanteric bursa and bluntly sweep it posteriorly to expose the short external rotators and the posterior edge of the gluteus medius. The posterior border of the gluteus medius is almost in line with the femoral shaft and the anterior border fans anteriorly.
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Maintain the hip in extension as the posterior dissection is performed. Flex the knee and internally rotate the extended hip to place the short external rotators under tension.
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Palpate the sciatic nerve as it passes superficial to the obturator internus and the gemelli. Complete exposure of the nerve is unnecessary unless the anatomy of the hip joint is distorted.
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Palpate the tendinous insertions of the piriformis and obturator internus and place tag sutures in the tendons for later identification at the time of closure.
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Divide the short external rotators, including at least the proximal half of the quadratus femoris, as close to their insertion on the femur as possible. Maintaining the length of the short rotators facilitates their later repair. Coagulate vessels located along the piriformis tendon and terminal branches of the medial circumflex artery located within the substance of the quadratus femoris. Reflect the short external rotators posteriorly while protecting the sciatic nerve.
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Bluntly dissect the interval between the gluteus minimus and the superior capsule. Insert blunt cobra or Hohmann retractors superiorly and inferiorly to obtain exposure of the entire superior, posterior, and inferior portions of the capsule.
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Divide the entire exposed portion of the capsule immediately adjacent to its femoral attachment. Retract the capsule and preserve it for later repair ( Figure 2-2 ).
Figure 2-2
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To determine leg length, insert a Steinmann pin into the ilium superior to the acetabulum and make a mark at a fixed point on the greater trochanter. Measure and record the distance between these two points to determine correct limb length after trial components have been inserted. Make all subsequent measurements with the limb in the identical position. Minor changes in abduction of the hip can produce apparent changes in leg-length measurements.
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We currently use a device that enables the measurement of leg length and offset. A sharp pin is placed in the pelvis above the acetabulum or iliac crest and measurements are made at a fixed point on the greater trochanter. An adjustable outrigger is calibrated for measurement of leg length and femoral offset ( Figure 2-3 ).
