Intraoperative Monitoring for the Lateral Lumbar Interbody Fusion Procedure

Inclusion Criteria: * At least 18 years of age at the time of planned surgery. * Indicated for 1- or 2-level instrumented LLIF surgery (in either prone or lateral decubitus positions), inclusive of the L4-5 disc space. * Written informed consent obtained from subject or subject's legal representative and ability for subject to comply with the requirements of the study. Exclusion Criteria: * Patients requiring surgical treatment at more than 2 lumbar levels. * Patients with peripheral neuropathy such as from diabetes or other conditions that might affect the reliability of intraoperative neuromonitoring. * Patients with prior history of partial/full hip or knee joint replacement surgery (i.e., arthroplasty or resurfacing) on the leg targeted for saphenous monitoring and electrode placement. * Patients with presence of a condition or abnormality that in the opinion of the Investigator would compromise the safety of the patient or the quality of the data. * Female patients who are pregnant or wanting to become pregnant during the timeframe of study participation. * Patients participating in another clinical study which may compromise this study's results or compliance with this study's procedures.