A novel preoperative trajectory evaluation method for L5-S1 transforaminal percutaneous endoscopic lumbar discectomy

BACKGROUND CONTEXT: L5-S1 transforaminal percutaneous endoscopic lumbar discectomy (PELD) is a demanding procedure because of structures such as iliac crest, L5 transverse process, hypertrophic L5-S1 facet joint, and sacral ala. There has been no definite preoperative evaluation method to evaluate the surgical validity of L5-S1 transforaminal PELD. PURPOSE: The authors report a new preoperative trajectory evaluation method for L5-S1 transforaminal PELD using magnetic resonance imaging (MRI) or computed tomography (CT) examinations. STUDY DESIGN/SETTING: This is a technical report study. PATIENT SAMPLE: Patients who were diagnosed L5-S1 soft disc herniation were included in the present study. OUTCOME MEASURES: Success rate of transforaminal PELD according to height of iliac crest was measured. METHODS: Twelve patients who were diagnosed L5-S 1 disc herniation were preoperatively evaluated with this new method. A skin marker is attached to patient's back as a tentative skin entry point, which was determined by usual preoperative MRI or CT. A new tilted axial and coronal MRI or CT scan is performed according to axis of L5-S1 transforaminal working channel. The images show good relationship between working channel and iliac crest. RESULTS: Six patients underwent a transforaminal PELD, and the results were successful. The other six patients were considered to be "unsuitable" for transforaminal PELD because of the probable blockade by iliac crest. CONCLUSIONS: The tilted MRI or CT provides precise evaluation for L5-S1 transforaminal PELD trajectory and may achieve good outcome. (C) 2018 Published by Elsevier Inc.