Posterior Approach to the Hip

The posterior approach is the most common and practical of those used to expose the hip joint. Popularized by Moore,9 it is often called the Southern approach.

All posterior approaches allow easy, safe, and quick access to the joint and can be performed with only one assistant. Because they do not interfere with the abductor mechanism of the hip, they avoid the loss of abductor power in the immediate postoperative period. Posterior approaches allow excellent visualization of the femoral shaft, thus are popular for revision joint replacement surgery in cases in which the femoral component needs to be replaced.

Because access to the joint involves division of the posterior capsule, if dislocation of any prosthesis occurs, it will result from flexion and internal rotation of the hip. Thus, there may be a higher dislocation rate than that from anterior approaches if the posterior approach is used in fractured neck of femur surgery in elderly bedridden patients who often lie in bed with their hips in a flexed and adducted position.

Their uses include the following:

1.   Hemiarthroplasty10–12

2.   Total hip replacement, including revision surgery

3.   Open reduction and internal fixation of posterior acetabular fractures

4.   Dependent drainage of hip sepsis

5.   Removal of loose bodies from the hip joint

6.   Pedicle bone grafting13

7.   Open reduction of posterior hip dislocations

Position of the Patient

Place the patient in the true lateral position, with the affected limb uppermost. Because most patients requiring surgery are elderly and have delicate skin, it is important to protect the bony prominences of the legs and pelvis with pads placed under the lateral malleolus and knee of the bottom leg and a pillow between the knees. Drape the limb free to leave room for movement during the procedure (Fig. 8-52).

Landmarks and Incision

Landmarks

Palpate in detail the greater trochanter on the outer aspect of the thigh. The posterior edge of the trochanter is more superficial than the anterior and lateral portions, and, as such, it is easier to palpate (see Fig. 8-27).

Incision

Make a 10- to 15-cm curved incision centered on the posterior aspect of the greater trochanter. Begin your incision some 6 to 8 cm above and posterior to the posterior aspect of the greater trochanter. The part of the incision that runs from this point to the posterior aspect of the trochanter is in line with the fibers of the gluteus maximus. Curve the incision across the buttock, cutting over the posterior aspect of the trochanter, and continue down along the shaft of the femur (Fig. 8-54A). If you flex the hip 90 degrees and make a straight longitudinal incision over the posterior aspect of the trochanter, it will curve into a “Moore-style” incision when the limb is straight. The final incision is curved and 10 to 15 cm long, centered on the posterior aspect of the greater trochanter.

Internervous Plane

There is no true internervous plane in this approach. However, the gluteus maximus, which is split in the line of its fibers, is not significantly denervated because it receives its nerve supply well medial to the split (Fig. 8-53).

Superficial Surgical Dissection

Incise the fascia lata on the lateral aspect of the femur to uncover the vastus lateralis. Lengthen the fascial incision superiorly in line with the skin incision, and split the fibers of the gluteus maximus by blunt dissection (Fig. 8-54B). (The fascial covering of the gluteus maximus

varies considerably in its thickness. In the elderly, it is quite thin.)

The gluteus maximus receives its blood supply from the superior and inferior gluteal arteries, which enter the deep surface of the muscle and ramify outward like the spokes of a bicycle wheel; hence, splitting the muscle inevitably crosses a vascular plane. In addition to the arterial bleeding, venous bleeding must be anticipated. If you split the muscle gently, you may be able to pick up, coagulate, and cut the crossing vessels before they are stretched and avulsed by the blunt dissection of the split. Obviously, vessels that are torn when stretched retract into the muscle and are more difficult to control.

Figure 8-52 Position of the patient on the operating table for the posterior approach to the hip joint.

Figure 8-53 There is no true internervous plane. Split the fibers of the gluteus maximus, a procedure that does not cause significant denervation of the muscle.

Deep Surgical Dissection

Retract the fibers of the split gluteus maximus and the deep fascia of the thigh. Underneath is the posterolateral aspect of the hip joint, still covered by the short external rotator muscles, which attach to the upper part of the posterolateral aspect of the femur (Fig. 8-55).

Remember that the sciatic nerve leaves the pelvis through the greater sciatic notch and runs down the back of the thigh on the short external rotator muscle, encased in fatty tissue. The nerve crosses the obturator internus, the two gemelli, and the quadratus femoris before disappearing beneath the femoral attachment of the gluteus maximus. You can find the nerve lying on the short external rotators, and it can be easily palpated. Do not dissect to see the nerve; you may cause unnecessary bleeding from the vessels lying in the fat around it (Fig. 8-56).

Internally rotate the hip to put the short external rotator muscles on a stretch (making them more prominent) and to pull the operative field farther from the sciatic nerve (Fig. 8-57A,B).

Insert stay sutures into the piriformis and obturator internus tendons

just before they insert into the greater trochanter. Detach the muscles 1 cm from their femoral insertion and reflect them backward, laying them over the sciatic nerve to protect it during the rest of the procedure (Fig. 8-57C). (The upper part of the quadratus femoris rarely may also have to be divided to fully expose the posterior aspect of the joint capsule, but the muscle contains troublesome vessels that arise from the medial circumflex artery. Normally, it should be left alone.)

The posterior aspect of the hip joint capsule is now fully exposed. The hip joint capsule can be incised with a longitudinal or T-shaped incision. Dislocation of the hip is achieved by internal rotation after capsulotomy (Fig. 8-58). Posterior joint capsulotomy will have exposed the femoral head and neck.

Figure 8-54 A: Skin incision for the posterior approach to the hip joint. B: Incise the fascia lata.

Figure 8-55 Retract the gluteus maximus to reveal the fatty layer over the short external rotators of the hip.

Figure 8-56 Push the fat posteromedially to expose the insertions of the short rotators. Note that the sciatic nerve is not visible; it lies within the substance of the fatty tissue. Place your retractors within the substance of the gluteus maximus superficial to the fatty tissue.

Figure 8-57 A, B: Internally rotate the femur to bring the insertion of the short rotators of the hip as far lateral to the sciatic nerve as possible. C: Detach the short rotator muscles close to their femoral insertion and reflect them backward, laying them over the sciatic nerve to protect it.

Dangers

Nerves

The sciatic nerve is rarely exposed or transected during this approach. However, it is sometimes involved in major complications. It can be damaged if it is compressed by the posterior blade of a self-retaining retractor used to split the gluteus maximus. Always keep the retractors on the cut surfaces of the rotators; the muscles will protect the nerve.

The sciatic nerve sometimes divides into its tibial and common peroneal branches within the pelvis; on occasion, you may expose these two “sciatic nerves” during this approach. If you have identified the sciatic nerve but think that it looks too small, search for the nerve’s other branch; it is in danger if it is overlooked.

Vessels

The inferior gluteal artery leaves the pelvis beneath the piriformis. It spreads cephalad to supply the deep surface of the gluteus maximus. Its branches are inevitably cut when the gluteus maximus is split; you can identify and coagulate them before they are avulsed if you are dissecting carefully.

The main trunk of the artery is vulnerable as it emerges from beneath the lower border of the piriformis when pelvic fractures involve the greater sciatic notch. If it retracts into the pelvis and bleeding is brisk, turn the patient over into the supine position, open the abdomen, and tie off the artery’s feeding vessel, the internal iliac artery.

Figure 8-58 Incise the posterior joint capsule to expose the femoral head and neck.

How to Enlarge the Approach

Local Measures

1.   Enlarge the skin incision. Obese patients may have a considerable layerof subcutaneous tissue over the buttock that restricts deep exposure; lengthening the skin incision and dissecting subcutaneously can compensate for this problem.

2.   Extend the fascial incision superiorly and inferiorly.

3.   Detach the upper half of the quadratus femoris. Because the musclecontains troublesome vessels, it should be divided about 1 cm from its insertion to make hemostasis easier. Its excellent blood supply is useful both when the muscle is transposed and in treatment of some cases of nonunion of femoral neck fractures (Fig. 8-59).

4.   Detach the insertion of the gluteus maximus tendon from the femur toincrease the exposure of the femoral neck and shaft. This maneuver is particularly useful during total joint replacement, especially revision joint replacement. If you detach the tendon, position acetabular retractors on the rim of the acetabulum as you would in the anterolateral approach. As long as the retractors are firmly on bone and do not crush soft tissues against the acetabular rim, no vital structures will be damaged (see Fig. 8-59).

Figure 8-59 To gain additional exposure, cut the quadratus femoris and the tendinous insertion of the gluteus maximus.