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Complications of Exposures for Total Hip Arthroplasty
Introduction
Total hip arthroplasty (THA) has evolved significantly since the development of Charnley’s low-fraction arthroplasty in the 1950s and is now one of the most common surgical interventions. , Excellent results have been described with multiple approaches, including the posterior, direct lateral, anterolateral, and direct anterior approaches. While complications can occur irrespective of approach, certain complications have been associated with each approach, albeit sometimes for historical reasons. This chapter describes selected complications as they relate to particular approaches. Further details are described in their respective chapters.
Posterior Approach
Intraoperative Complications
Sciatic Nerve Injury
Neurologic injury after primary THA is rare, occurring at rates between 0.1% to 1.9%. Of these injuries, sciatic nerve palsy is the most common nerve injury after THA. It most often affects the peroneal division, resulting in a clinical presentation of foot drop. , The posterior approach is one risk factor, along with hip dysplasia, excessive limb lengthening, revision surgery, and lumbar spine disease. The sciatic nerve may be at higher risk during the posterior approach secondary to its proximity to the surgical field. The peroneal division of the sciatic nerve is lateral to the tibial division; thus, it may be more vulnerable to compression by deep retractors during a posterior approach. Other less-common causes of sciatic nerve injury include hematoma formation (most commonly in patients on anticoagulation medication), polymethyl methacrylate (PMMA)-induced thermal damage, neural impingement from extruded and hardened PMMA, as well as intraoperative neural laceration by scalpel, reaming, or wires or cables.
Limb positioning appears to have a role in sciatic nerve palsy. Shiramizu et al. used interoperative motor evoked potentials (MEPs) to monitor the sciatic nerve during the dislocation portion of 23 posterolateral approach THAs. Although no patients experienced nerve palsy afterwards, the authors observed significantly increased distal motor latencies in all positions other than 60 degrees of hip flexion and 60 degrees of internal rotation. Satcher et al. reported the results of monitoring the sciatic nerve via MEPs and electromyography (EMG) during 27 posterolateral revision THAs. The authors found that significant electrical events occurred most commonly during acetabular reconstruction and recommended avoiding hip flexion during posterior acetabular retraction.
Surgical intervention may be considered for readily identifiable causes of neurologic compromise, including hematoma formation, significant limb lengthening, cement extrusion, or the possibility of damage by knife or suture. , , , Additionally, the presence of pain in the distribution of the sciatic nerve signifies a continuing insult to the nerve and should prompt urgent exploration. Surgeons may reduce injury to the sciatic nerve by placing the posterior acetabular retractor within the hip capsule with the operative limb in extension to allow the nerve to displace posteriorly. Surgeons should exercise caution when placing posteroinferior acetabular screws in a revision setting. During all cases, the surgeon should be attentive to retractor placement, avoid excessive traction during hip dislocation, avoid exploration of the nerve, and avoid prolonged rotation of the limb during femoral exposure or hip flexion during acetabular exposure.
Postoperative Complications
Dislocation
The posterior approach for THA has historically been associated with higher rates of dislocation compared with other approaches, up to 13% in some series. The inherent risk is likely secondary to violation of the short external rotator muscles and of the weaker ischiofemoral ligament of the posterior capsule. However, the posterior approach has been refined since its initial description. Modern techniques, including larger-diameter heads and posterior capsular repair, have reduced dislocation rates to be comparable to other approaches in recent years. Publications by Pellicci et al. and Mead described posterior capsular repair, reducing dislocation rates below 1%. , A 2002 systematic review of 13,203 primary THAs found a dislocation rate of 3.95% without posterior soft-tissue repair in comparison to 2.03% with posterior repair.
During the initial approach, dissection through the short external rotator muscles should be undertaken with care. In addition to the conjoined tendon of the gemelli and obturator internus, the piriformis or quadratus femoris or both are released. Some surgeons choose to release the tendons separately from the capsule, while others release both as a “capsuloligamentous sleeve.” All tendons and capsules should be released directly off the posterior edge of the femur in order to allow as much soft tissue as possible for repair. Tagging sutures may be used to assist in capsular mobilization as needed. For the posterior soft-tissue repair, heavy absorbable or nonabsorbable sutures are passed through the posterior capsule and tendons. The sutures are then passed through the posterior trochanteric ridge of the femur via drill holes and tied down over the femur.
Though most studies report good rates of success, there have been reports of high rates of posterior instability, even after posterior soft-tissue repair. , To address this concern, Kim et al. developed a modification of the posterior approach for THA involving preservation of the piriformis, superior gemelli, and obturator internus while releasing the inferior gemelli and obturator externus. The posterior capsule is exposed by retracting the obturator internus proximally and quadratus femoris distally with blunt retractors. In their retrospective review of 670 hips 1 year after posterior approach THA, the authors found zero dislocations when the short external rotator (SER) muscles were not disrupted, as compared with a 3.9% rate of dislocation with posterior repair and a 5.3% rate of dislocation when the SERs were excised ( Fig. 17.1 ).
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