This study is designed to evaluate the clinical utility of a known intraoperative neuromonitoring modality (SSEP) using saphenous nerve as the site of stimulation to identify changes to the lumbar nerves which may be at risk during the lateral lumbar interbody fusion (LLIF) 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.

Patients of both sexes undergoing LLIF surgery atone or two levels inclusive of the L4-5 level.