UBE-TFD for lumbar foraminal stenosis and extreme lateral disc herniation: a preliminary case series of Doom's Point vs. pars interarticularis localization.

Abstract

To compare the clinical efficacy, radiological outcomes, and safety of unilateral biportal endoscopic transforaminal foraminoplasty and discectomy (UBE-TFD) using a novel anatomical landmark ("Doom's Point," the transverse process-superior articular process [TP-SAP] confluence) versus conventional pars interarticularis localization for refractory lumbar foraminal stenosis (LFS) and extreme lateral disc herniation (ELDH). A retrospective analysis was conducted on 46 consecutive patients (Lee classification ≥ III for LFS/ELDH) who underwent UBE-TFD between March, 2023, and December, 2024. Patients were divided into two groups: 24 cases with Doom's point localization (Group A) and 22 cases with pars interarticularis localization (Group B). Perioperative parameters (operative time, intraoperative blood loss, fluoroscopy time, incision-to-spinous process midline distance), clinical outcomes (visual analog scale [VAS] for back/leg pain, Oswestry Disability Index [ODI]) at baseline and 1-year follow-up, radiological outcomes (foraminal area via 3D CT), and complications were recorded. Statistical analyses were performed using R software (Version 4.3.1) with paired t-tests, independent samples t-tests, and χ2/Fisher's exact tests (α = 0.05). Baseline characteristics were comparable between groups (all p > 0.05). Among perioperative parameters, Group A had a significantly larger incision-to-spinous process midline distance (7.9 ± 0.6 vs. 5.8 ± 0.5 cm, p < 0.001), while operative time (72.2 ± 15.5 vs. 80.5 ± 14.9 min, p = 0.421), intraoperative blood loss (47.9 ± 7.5 vs. 46.8 ± 7.1 mL, p = 0.563), and fluoroscopy time (9.2 ± 2.7 vs. 10.3 ± 3.1 s, p = 0.189) showed no significant differences between groups. At 1-year follow-up, both groups exhibited significant improvements in back/leg pain VAS and ODI scores compared with baseline (all p < 0.001), but Group A demonstrated superior clinical outcomes: lower leg pain VAS (1.1 ± 0.5 vs. 2.1 ± 0.8, p = 0.009) and ODI (10.1 ± 3.7% vs. 16.5 ± 4.6%, p = 0.007), alongside higher leg pain improvement rate (79.2 ± 7.6% vs. 60.9 ± 9.3%, p = 0.001) and function improvement rate (75.1 ± 7.0% vs. 57.8 ± 8.7%, p = 0.002). Radiologically, the foraminal area increase rate was significantly higher in Group A (83.1 ± 7.9% vs. 65.7 ± 8.0%, p = 0.002), correlating with its clinical benefits. In terms of safety, Group A had a more favorable profile: fewer cases of transient paresthesia (2 [8.3%] vs. 7 [31.8%], p = 0.017) and no exit nerve root injuries (0 [0%] vs. 3 [13.6%], p = 0.029). No major complications (e.g., dural tear, infection) or segmental instability were observed in either group. Furthermore, inter-observer consistency for Doom's Point localization was excellent (weighted Kappa = 0.89; intraclass correlation coefficient [ICC] = 0.92), confirming its reliability across surgeons of varying seniority. UBE-TFD demonstrates favorable short-term outcomes for selected foraminal pathologies. Larger prospective studies are warranted to validate these findings.