Transforaminal Full-Endoscopic Ventral Facetectomy: Midterm Results and Factors Associated with Poor Surgical Outcomes
Authors: Kishima Kazuya , Yagi Kiyoshi , Yamashita Kazuta , Tezuka Fumitake , Morimoto Masatoshi , Takata Yoichiro , Sakai Toshinori , Maeda Toru , Sairyo Koichi 
Published: December 2022

Background Full-endoscopic spine surgery (FESS) is a well-established procedure for herniated nucleus pulposus. It is a minimally invasive surgery that can be performed under local anesthesia through only an 8-mm skin incision. With improvements in surgical equipment such as high-speed drills, the indications for FESS have expanded to include lumbar spinal stenosis (LSS). We perform a transforaminal full-endoscopic ventral facetectomy (TF-FEVF) for unilateral nerve root–type lateral recess stenosis (LRS) using a transforaminal approach under local anesthesia.

The aim of this study was to examine the postoperative results of TF-FEVF for LRS and to identify factors associated with poor surgical outcomes. 85 patients who underwent TF-FEVF for LRS under local anesthesia. Clinical outcomes were determined by visual analog scale (VAS) and the modified MacNab criteria. Evaluation was performed using magnetic resonance imaging (MRI), computed tomography (CT), and flexion–extension radiographs.

Methods This study involved 85 patients (47 males and 38 females) who underwent TF-FEVF for LRS. The mean age was 70.5 years and the mean follow-up duration was 14.8 months. Data were collected on sex, age, level of operation, diagnosis, history of spine surgery at the same level, and duration of follow-up. The diagnosis was categorized as LSS with or without disk bulging. Clinical evaluation was performed using the VAS and modified MacNab criteria. MRI was used to evaluate the degree of disk degeneration, vertebral endplate degeneration, disk height, thickening of the ligamentum flavum, and stenosis. Bony stenosis was evaluated using CT. Sagittal translation and sagittal angulation were also measured by flexion–extension radiographs, and the Cobb angle was measured using a standing front view radiograph. All variables were compared between patients with excellent/good outcomes (E/G group) and those with fair/poor outcomes (F/P group) using the modified MacNab criteria.

Results Postoperative VAS showed that leg pain decreased from 59.0 ± 28.6 preoperatively to 17.9 ± 27.2 at the final follow-up (p < 0.01) and that lower back pain also decreased from 60.7 ± 26.6 preoperatively to 27.3 ± 28.6 at final follow-up (p < 0.01). According to the modified MacNab criteria, the results during the final follow-up were excellent in 39 cases, good in 21 cases, fair in 13 cases, and poor in 12 cases. There were no significant differences in sex, age, diagnosis, history of spine surgery, and duration of follow-up periods between the 60 cases (70.6%) in the E/G group and the 25 cases (29.4%) in the F/P group. Imaging evaluation revealed statistically significant differences between the E/G group and the F/P group in intervertebral angle flexion (3.2 vs. 0.4 degrees; p < 0.05), sagittal angulation (4.3 vs. 8.1 degrees; p < 0.05), slip in flexion (0.9 vs. 2.8 mm; p < 0.05), sagittal translation (0.7 vs. 1.6 mm; p < 0.05), and Cobb angle (−0.5 vs. −1.9 degrees; p < 0.05).

Conclusion Midterm results of TF-FEVF were generally favorable; factors contributing to good or poor TF-FEVF outcomes were large sagittal angulation, large sagittal translation, and concave side.