Revision Total Hip Arthroplasty with Femoral Component Retention.

Background: Revision total hip arthroplasty (THA) for isolated polyethylene exchange or acetabular revision with retention of the femoral component can present a challenge for adequate exposure. A systematic approach to a proper release can facilitate exposure and reduce the risk of iatrogenic complications. Description: The posterior approach is an extensile and versatile approach for revision THA. After incising the fascia and iliotibial band, the insertion of the gluteus maximus is fully released. After releasing any scar along the inferior gluteus medius, a retractor is placed to hold the muscle belly cranially. The leg is gently internally rotated to place the posterior capsule and external rotators under tension while these structures are released from the posterior femur and along the neck of the femoral component. Curved scissors can be utilized to identify the psoas sheath and to release the inferior capsule while protecting the iliopsoas tendon. Scar tissue is resected from inside the hip joint, and a pocket is made in the anterior capsule to allow retractor placement above the equator of the acetabulum in order to hold the mobilized proximal femur anteriorly. An inferior retractor is then placed under the transverse acetabular ligament. This systematic approach allows adequate visualization of the acetabular component for revision. Alternatives: Nonoperative treatment should be attempted first, depending on the diagnosis and its associated natural history. Once nonoperative treatment has been exhausted and revision THA is indicated, the anterior and direct lateral approaches can be considered. If the femoral component needs revision on the basis of intraoperative assessment, the anterior approach presents substantial difficulty in femoral exposure, with a higher risk of iatrogenic fracture. The direct lateral approach commonly leads to abductor weakness and a Trendelenburg gait. Rationale: Common indications for revision THA with femoral component retention include wear and/or osteolysis, adverse local tissue reaction, recurrent instability, and aseptic acetabular loosening. Adequate exposure is essential to facilitate revision THA with femoral component retention and to minimize the risk of iatrogenic injury. Expected Outcomes: Survivorship free from re-revision at 2 years is >80% for both isolated polyethylene exchange and acetabular revision. There is a trend toward higher failure rates when retaining the acetabular component. Risk factors for failure include damage to the locking mechanism; femoral head erosion into the cup, damaging the metal; and a mispositioned acetabular component. Important Tips: A systematic approach to releases is essential for adequate exposure with a retained femoral component. Systematic releases include fully releasing the gluteus maximus insertion, continuing the iliotibial band incision distally, fully releasing the external rotators, and removing scar tissue within the joint.Keeping the hip extended and the knee flexed with a finger posteriorly is important to protect the sciatic nerve during the release of the posterior capsule. The hip can then be dislocated in a controlled manner to reduce the risk of iatrogenic injury.Be prepared for bleeding from perforating arteries during subvastus elevation.Rest the leg on a padded Mayo stand in slight internal rotation once the proximal femur is retracted anteriorly.Ensure proper component alignment, component stability, and hip stability to confirm that femoral component retention is indicated. Repair of the posterior capsule contributes substantially to postoperative stability.Precautions should be implemented postoperatively to reduce the risk of dislocation. A hip abduction brace can be considered for patients at a high risk of instability.Active ankle dorsiflexion should be assessed in the post-anesthesia unit to evaluate for sciatic nerve injury and to differentiate the cause of a foot drop if discovered on postoperative day 1. Acronyms and Abbreviations: AP = anterior-posteriorCT = computerized tomographyCRP = c-reactive proteinESR = erythrocyte sedimentation rateFDA = Food & Drug AdministrationHR = Hazard ratioIT = Iliotibial bandMSIS = Musculoskeletal Infection SocietyOR = Odds ratioTHA = total hip arthroplastyrTHA = revision total hip arthroplasty.