Avoidance and management of neurovascular injuries in total hip arthroplasty.

Neural injuries that occur after total hip arthroplasty (THA) can be classified as involving either the central nervous system or peripheral nerves. Central nervous system changes after THA may be attributed to increased appreciation of fat embolism syndrome associated with THA. Certain maneuvers such as impacting the acetabulum, femoral reaming, and cement pressurization can force marrow fat into the venous system. When there is an associated right to left shunt, paradoxical embolization can occur, which may account for previously unexplained cases of confusion and mental status changes after surgery. Peripheral nerve injuries are rare and can involve either distant sites or nerves in the immediate vicinity of the hip joint. Upper extremity nerve injuries are usually associated with patient positioning. Sciatic nerve injury is the most common nerve injury following THA. In comparison, femoral nerve injury is much less common and is associated with an anterior approach. Diagnosis is often delayed, and the prognosis is generally better than with sciatic nerve injury. The superior gluteal nerve is at risk during the direct lateral approach. Obturator nerve injury is the least common type of injury and has the least functional consequence. It can present as groin or inguinal pain. Vascular injuries are less common but more immediately life threatening. The mechanisms of vascular injury include occlusion associated with preexisting peripheral vascular disease and vascular injury during removal of cement during screw fixation of acetabular components, cages, or structural grafts. Perioperative assessment should include vascular evaluation of patients with absent pulses, previous vascular bypass surgery, or dysvascular limbs. A CT scan should be considered when cement or components extend medially into the pelvis.