North American Spine Society Journal (NASSJ) · Published 2026-02-20 · DOI 10.1016/j.xnsj.2026.100870
ABSTRACT: Background: Adjacent segment degeneration (ASD) following transforaminal lumbar interbody fusion (TLIF) lacks a standardized classification system that integrates both clinical and radiological parameters. We aimed to develop and internally validate a novel clinico-radiological classification system for lumbar ASD after TLIF and to evaluate its association with surgical intervention. Methods: We retrospectively analyzed 150 patients who underwent one- or two-level TLIF with a minimum follow-up of 5-years. Clinical variables (low back pain [LBP], radiculopathy, neurogenic claudication, and neurological deficit) and radiographic/magnetic resonance imaging (MRI) findings were assessed. Latent class analysis (LCA) identified 5 distinct classes, forming a five-grade system: Grade 0: Nil or occasional LBP with normal imaging; Grade 1: Continuous LBP with mild radiological degeneration without instability; Grade 2: Radicular pain with moderate degeneration and/or instability; Grade 3: Neurogenic claudication with advanced degeneration and severe central stenosis; and Grade 4: Neurological deficit and/or proximal junctional kyphosis or failure. Internal validation was performed in 30 independent cases using Fleiss’ kappa. Firth’s penalized logistic regression was used to identify predictors of surgical intervention. Results: The classification demonstrated substantial inter-observer agreement (κ = 0.74) and excellent intra-observer reliability (κ = 0.82). Surgical intervention was strongly associated with higher grades: 87% of patients in Grades 3–4 underwent surgery compared to 6.7% in Grades 0–2 (p < .001). High-grade ASD (odds ratio [OR] 24.30; p < .001) and diabetes mellitus (OR = 3.24; p = .005) were independent predictors of surgery. The average grading time was 2-3 minutes per case. Conclusions: This novel clinico-radiological classification system for lumbar ASD after TLIF is reliable, practical, and strongly associated with surgical decision-making. It may aid in clinical stratification and follow-up planning. Prospective multicenter validation is warranted.
Abstract from DOAJ. Public domain (CC0 1.0).
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