Spine Journal - 2026-06-09 - Journal Article; Review
Predicting cage subsidence after lumbar interbody fusion: a meta-analysis of opportunistic bone quality metrics.
Patel S, Nischal SA, Nallankuka GS, Kale KM, Sarikonda A, Saad H, Hines KJ, Jallo J, Harrop JS, Prasad SK
Topics
Key Takeaway
Across 5,482 patients, all imaging-derived bone quality metrics (HU, CT-BMD, VBQ, EBQ, DEXA T-score) showed moderate-to-good discrimination for cage subsidence with pooled AUCs of 0.77–0.85, but no single metric was statistically superior.
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Summary
This systematic review and meta-analysis evaluated CT- and MRI-derived bone quality metrics as preoperative predictors of cage subsidence in degenerative lumbar interbody fusion. Patients who developed subsidence (30.6% of the cohort) had significantly lower HU (MD -26.9), lower CT-BMD (MD -33.0), lower DEXA T-scores (MD -0.77), higher VBQ (MD +0.60), and higher EBQ (MD +0.68), all p<0.01. Pooled AUCs ranged from 0.77 to 0.85 across metrics, with meta-regression showing no statistically significant difference in discriminative performance between modalities.
Key Limitation
Heterogeneous definitions of cage subsidence across included studies (varying thresholds from 2 mm to >25% endplate violation) preclude determination of a single clinically actionable cutoff for any metric.
Original Abstract
BACKGROUND CONTEXT
Cage subsidence (CS) is a frequent complication following lumbar interbody fusion and is closely linked to vertebral and endplate bone quality. Although CT- and MRI-derived bone metrics are increasingly used for preoperative risk stratification, their comparative discriminative performance for CS has not been systematically evaluated.
PURPOSE
To evaluate and compare the discriminative performance of CT- and MRI-derived bone quality metrics for CS following degenerative lumbar fusion.
STUDY DESIGN/SETTING
Systematic review and meta-analysis.
METHODS
PubMed, Embase, and CENTRAL were searched from inception to January 2026. Observational studies reporting preoperative imaging-based bone quality metrics in adult patients undergoing lumbar interbody fusion were included. Primary metrics included CT-based Hounsfield units, MRI-based vertebral bone quality (VBQ) and endplate bone quality (EBQ), and CT-derived bone mineral density (CT-BMD). Secondary outcomes included DEXA T-scores. Random-effects meta-analyses synthesized continuous inter-group differences and diagnostic accuracy parameters, summarized using pooled sensitivity, specificity, likelihood ratios, diagnostic odds ratios, and SROC curves. Risk of bias was assessed using QUADAS-2.
RESULTS
Thirty-six studies encompassing 5482 patients were included, of whom 1679 (30.6%) developed CS. Across all metrics, patients with subsidence demonstrated poorer preoperative bone quality, including lower Hounsfield units (MD -26.9; P < 0.01), lower CT-BMD (MD -33.0; P < 0.01), and lower DEXA T-scores (MD -0.77; P < 0.01), alongside higher VBQ (MD 0.60; P < 0.01) and EBQ scores (MD 0.68; P < 0.01). Diagnostic accuracy was moderate-to-good, with pooled AUCs ranging from 0.77 to 0.85. Differences in discriminative performance between metrics were modest and non-significant on meta-regression, with nomogram analyses demonstrating risk-shifting rather than definitive rule-in or rule-out performance.
CONCLUSIONS
Imaging-derived bone quality metrics demonstrate consistent associations and moderate-to-good discrimination for CS after degenerative lumbar fusion, reflecting shared vulnerability at the cage-endplate interface and supporting their use as pragmatic tools for preoperative risk stratification and surgical planning.