The posterolateral approach to the hip may be done with the patient in lateral decubitus or prone positions. For arthroplasty, a lateral decubitus position is usually chosen. The approach is essentially the same as the Kocher-Langenbeck, but exposure is limited to the hip joint, respecting but not displaying the sciatic nerve. The femoral attachment of the short external rotators and hip capsule should be repaired to reduce the risk of postoperative dislocation. (Early descriptions of hip arthroplasty through a posterolateral approach suggested excision of the posterior hip capsule.)
After posterior capsulotomy, the hip is dislocated with internal rotation.
The patient is placed in the lateral decubitus position, with supports to prevent rotation away from true lateral, and appropriate padding to limit focal pressure.
After sterile preparation of the hip region, the involved leg is draped free, to permit full mobility.
3. Skin incision
Outline all bony landmarks with a sterile marking pen:
Posterior superior iliac spine (PSIS)
Shaft of femur
Start the skin incision posterior to the lateral side of the greater trochanter and carry it distally about 6 cm along the femoral axis. Proximally, the incision runs slightly curved towards the PSIS to a point approximately 6 cm proximal to the greater trochanter.
4. Dissection of fascia lata
Straight sharp dissection of the fascia lata and gluteal muscle across the greater trochanter. Incise the fascia lata in line with the skin incision.
5. Protection of sciatic nerve
Retraction of the gluteal muscle flap posteriorly shows short external rotators inserting on femur (at least partially obscured by fat). The sciatic nerve can be palpated posteriorly in the depths of the wound. Its exposure is not necessary for uncomplicated hip arthroplasty, but the surgeon should be aware of the nerve’s location, and avoid injuring it with retractors.
6. Exposure of short rotator tendons
Bluntly dissect the tendinous insertions of the short external rotators. Before dividing the tendons, place heavy, nonabsorbable stay sutures for retraction and subsequent repair. One suture can be placed in the piriformis tendon, and the other in the conjoined tendons of obturator internus and gemelli.
7. Divide and reflect short rotators
Reflection of the short rotator muscles exposes the hip capsule. Next, enter the joint with a broad-based, 3-sided capsulotomy as shown. Preserve the acetabular labrum, unless total hip arthroplasty is intended.
Expose the hip joint by creating and reflecting a full thickness, broad-based flap of the posterior hip capsule. Heavy (eg #2) non-absorbable sutures in its free corners aid retraction and subsequent repair.
At the completion of the procedure, the posterior capsular flap sutures, and then the tendon sutures, are tied to each other after being passed through drill holes in the posterior greater trochanter. Quadratus femoris, if divided, is repaired separately. A secure repair of the tendons and capsule decreases the risk of hip prosthesis dislocation after a posterior approach.