Wake-up test in total hip arthroplasty with high-riding developmental dysplasia

Total hip arthroplasty (THA) for patients with Crowe type IV developmental dysplasia of the hip is technically challenging. This group of patients has a higher incidence of nerve injury during THA. Although neurophysiologic intraoperative monitoring has been developed to provide nerve monitoring, it is not always available. The wake-up test has been used for intraoperative spinal cord monitoring during major spinal surgery, but no study has reported the use of the wake-up test for neurologic monitoring during THA in patients with severe developmental dysplasia of the hip. The authors retrospectively reviewed 22 THA procedures in 20 patients with Crowe type IV developmental dysplasia of the hip who underwent the wakeup test during THA. In the current study, 1 patient could not dorsiflex her foot during the wake-up test. Therefore, the authors immediately reduced the length of limb lengthening by 1 cm. Postoperative drop foot and numbness occurred but resolved completely 2 months later. None of the patients who showed no deficits in motion of the feet during the intraoperative wake-up test had signs of postoperative nerve injury. In the current study, there was no false-positive or false-negative finding. The authors concluded that the wake-up test, which is simple, safe, and reliable, is a useful technique and a possible alternative to neurophysiologic intraoperative monitoring in checking nerve function during THA in patients with severe developmental dysplasia of the hip.