Risk Factors of Restenosis After Full Endoscopic Foraminotomy for Lumbar Foraminal Stenosis: Case-Control Study

OBJECTIVE: To investigate risk factors associated with postoperative restenosis after full endoscopic lumbar foraminotomy (FELF) in patients with lumbar foraminal stenosis (LFS). METHODS: A single-center, retrospective case-control study was conducted on patients diagnosed with foraminal stenosis who underwent FELF between August 2019 and April 2022. The study included 56 patients, comprising 18 cases and 38 controls. Clinical data, radiologic assessments, and surgical types were compared between the groups. The cutoff values of radiologic parameters that differentiate the 2 groups were investigated. RESULTS: No significant difference in age, sex distribution, or presence of adjacent segment disease or grade I spondylolisthesis was observed between the groups. Cases had a higher degree of disc wedging angle (DWA) (3.0°±1.1° vs. 0.5°±1.4°, p < 0.001), larger coronal Cobb angle (CCA) (8.8°±5.1° vs. 4.7°±2.5°, p = 0.004), and smaller segmental lumbar lordosis (SLL) than controls (11.0±7.4 vs. 18.0±5.4, p = 0.001). Optimal cutoff values for DWA, CCA, and SLL were estimated as 1.8°, 7.9°, and 17.1°, respectively. A significant difference in surgical types was observed between cases and controls (p = 0.004), with the case group having a higher distribution of patients undergoing discectomy in addition to TELF. CONCLUSION: The study identified potential risk factors for restenosis after FELF in patients with LFS, including higher DWA, larger CCA, smaller SLL angle. We believe that discectomy should be perform with caution during FELF, as it can lead to subsequent restenosis.