Intraoperative Neuromonitoring During Periacetabular Osteotomy Provides Actionable Alerts.

Background: Bernese periacetabular osteotomy (PAO) for symptomatic acetabular dysplasia and femoroacetabular impingement has become increasingly common, with a corresponding increase in the incidence of adverse outcomes. The rate of major neurological injury (excluding lateral femoral cutaneous nerve injury) during PAO has been reported to be around 2%. Previous publications have recommended the use of intraoperative neuromonitoring (IONM) to mitigate risk of major neurological injury during PAO, but its use has not become universal among PAO surgeons as it has among spine surgeons. The purpose of this study was to report the incidence and clinical significance of IONM alerts in a single-surgeon, consecutive cohort of patients treated with Bernese PAO. Methods: After a permanent peripheral nerve injury during a PAO without IONM, IONM has been used at our institution in every PAO. Motor evoked potentials and somatosensory monitoring are performed throughout the procedure. We conducted a retrospective review of all PAOs performed after this practice change between 2017 and 2023. Medical records were reviewed for all IONM alerts, surgical team responses to alerts, and postoperative neurological status. Results: All 94 PAOs performed with IONM in 82 patients during the study period were included. The mean age was 19 years (range 11-38). Significant IONM alerts occurred in 10 of 94 PAOs (11%) in 10 patients. Of these 10 alerts, 6 resulted in action taken by the surgical team including adjustment of acetabular fragment correction, leg repositioning, or stockinette or boot loosening. The remaining 4 alerts were due to anesthetic or systemic causes or technical issues with the neuromonitoring electrodes. No patients had a detectable neurological deficit postoperatively. Conclusions: IONM may produce alerts in approximately 1 in 9 periacetabular osteotomies. These alerts are actionable and may improve patient safety and minimize the non-negligible risk of major nerve injury. This study provides additional evidence to support the utility of IONM in PAO. Level of Evidence: Level III-retrospective cohort study. See Instructions for Authors for a complete description of levels of evidence.