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A Novel Scoring System for Predicting Procedural Difficulty in Supraneural L5 TFESI: The L5 TFESI Difficulty Score
1Department of Physical Medicine and Rehabilitation, Inje University Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Republic of Korea.
Introduction:
Supraneural transforaminal epidural steroid injections (TFESI) at the L5 level are widely used to manage lumbosacral radiculopathy. However, fluoroscopic barriers such as prominent osteophytes and altered transverse process morphology can complicate needle advancement and reduce the likelihood of optimal injectate delivery. Despite these procedural challenges, no standardized grading system currently exists to objectively quantify anatomical complexity or predict technical difficulty during L5 supraneural TFESI.
Methods:
This study included 584 L5 supraneural TFESI cases performed in 273 L5 radicular lesions aged above 60. All procedures were performed under standardized fluoroscopic guidance by a single experienced pain physician using a consistent supraneural approach. The LTDS comprises six fluoroscopic criteria reflecting anatomical barriers at the L5/S1 level. The patients were stratified into three LTDS groups (Low, 0-3; Middle, 4-6; High, 7-10). Procedural outcomes were assessed based on needle position and the pattern of contrast spread. Receiver operating characteristic (ROC) analysis was performed to assess the discriminative performance of the LTDS for predicting epidurogram failure.
Results:
Higher LTDS scores were significantly associated with longer procedure times and lower rates of optimal TFESI execution. Each one-point increase in LTDS decreased the odds of successful injection by approximately 40%. ROC analysis demonstrated fair discriminative ability (AUC = 0.707; 95% CI, 0.651-0.764; p < 0.001). While an LTDS threshold of ≥ 5.5 provided the optimal balance between sensitivity and specificity, higher thresholds showed markedly increased specificity, indicating that the LTDS preferentially identifies cases with a high likelihood of technical difficulty rather than serving as a sensitive screening tool. The inter- and intra-rater reliabilities of the LTDS were high (Cronbach's α = 0.886 and 0.891, respectively).
Conclusions:
The LTDS demonstrates meaningful discriminative performance and high reliability for stratifying technical difficulty in L5 supraneural TFESI. Rather than functioning as a rigid predictor of failure, the LTDS serves as a practical decision-support tool that may assist in preprocedural planning, approach selection, and operator training in patients with advanced lumbar degeneration.
