Improved Iliac Exposure and Abductor Function with an Extended Posterior Approach for Revision Total Hip Arthroplasty.

Abstract

Background: Achieving adequate exposure can be difficult in cases of revision total hip arthroplasty (THA). Splitting the gluteus maximus muscle with use of a Kocher-Langenbeck approach is the most common technique when performing a posterior approach to the hip. However, superior exposure of the ilium is limited by the superior gluteal neurovascular bundle (SGB). Additionally, postoperative abductor weakness has been associated with this approach.

Description: The extensile posterior approach (Adelaide approach) mobilizes the gluteus maximus muscle posteriorly and the gluteus medius muscle anteriorly to expose the ilium superior to the sciatic notch while minimizing the risk of injury to the SGB and preserving abductor function. Above the greater trochanter, the skin incision extends in a straight line toward the halfway point between the iliac tuberosity and the posterior superior iliac spine. It is helpful to find and protect the perforator vessels to identify the anterior edge of the gluteus maximus and develop a plane between the gluteus maximus and medius. The fascial incision is made with a slight Z shape for a modified Gibson approach. The gluteus maximus tendon is transected and the muscle is reflected posteriorly to expose the gluteus medius. The gluteus medius is elevated off the posterior gluteal line proximally to distally. The superior aspect of the SGB and transverse ligament are exposed, and the anterior aspect of the transverse sciatic notch ligament is released. The gluteus medius is mobilized anteriorly to expose the SGB, which is easier in a proximal-to-distal direction. Following the mobilization of the SGB, cage flanges can be passed underneath or augments bridged over the SGB without placing the SGB under undue tension.

Alternatives: Nonoperative treatment should be attempted first, depending on the diagnosis and the patient's associated natural history. Once nonoperative treatment has been exhausted and revision THA is indicated, the traditional posterior, anterior, and direct lateral approaches can also be considered. If intraoperative assessment shows that the femoral component needs to be revised, the anterior approach presents substantial difficulty in femoral exposure and is associated with a higher risk of iatrogenic fracture. The direct lateral approach commonly leads to abductor weakness and a Trendelenburg gait postoperatively. The traditional posterior approach places the superior gluteal nerve at a higher risk for injury, which can lead to postoperative abductor weakness.

Rationale: Common indications for revision THA include osteolysis, adverse local tissue reaction, recurrent instability, and aseptic acetabular loosening. Adequate exposure is essential to facilitate THA reconstruction while minimizing the risk of iatrogenic nerve injury.

Expected outcomes: In a series of 9 patients with Paprosky 3B defects (5 with pelvic discontinuity) who underwent this technique, all had preserved innervation of the gluteal muscles on intraoperative electromyography and good abduction function postoperatively. For comparison, in a matched cohort of 9 patients who underwent a traditional Kocher-Langenbeck approach, 7 (78%) had persistent abductor weakness.

Important tips: Isolate and place a vessel loop around the SGB to allow for adequate mobilization of the gluteus medius without causing undue tension on the nerve.

Acronyms and abbreviations: SGB = superior gluteal neurovascular bundleTHA = total hip arthroplastyFDA = Federal Drug AdministrationASIS = anterior superior iliac spinePSIS = posterior superior iliac spineGT = greater trochanterG = gluteusDDH = developmental dysplasia of the hips/p = status postyo = year oldSTSO = subtrochanteric shortening osteotomyPS = posterosuperiorNV = neurovascularIT = intertrochantericEMG = electromyography.