Cage rotation and effective rim support are associated with subsidence after TLIF using a single expandable banana-shaped cage design
- Journal
- European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society (Q1)
- Published
- 4 November 2026
- Study design
- Prospective / inception cohort
- Evidence level
- Level 2, Moderate (CEBM 2b)
- Authors
- Hiromi Kumamaru, Hideki Jimbayashi, Yoshihiro Ito, Ken Kijima, Yasuharu Nakashima, Katsumi Harimaya
- PMID
- 42980784
- DOI
- 10.1007/s00586-026-10474-6
Why clinicians should know about it
- Picked for Spine Surgery (top studies of the week, 8 November 2026): TLIF cage placement factors associated with subsidence
Abstract
PURPOSE: To determine whether postoperative cage obliquity and vertebral rim support are associated with 12-month subsidence after TLIF using a single articulating expandable banana-shaped cage design. METHODS: We retrospectively reviewed 101 patients (109 levels) treated with an articulating expandable banana-shaped cage. Postoperative CT was used to measure cage obliquity angle and cage-rim contact ratio. Subsidence was defined as ≥ 2 mm at 12 months. Spearman correlations were used to examine relationships between cage obliquity and rim-support metrics. Associations of cage obliquity and cage-rim contact with subsidence were evaluated using separate multivariable logistic regression models adjusted for Hounsfield units. Spatial heatmaps visualized the distribution of anterior rim support, which was further quantified using mediolateral contact metrics. RESULTS: Subsidence occurred in 16 levels (14.7%). Greater cage obliquity angle was associated with subsidence (OR 1.40 per 5°, 95% CI 1.10-1.84, p = 0.004), whereas greater cage-rim contact ratio was inversely associated with subsidence (OR 0.68 per 10%, 95% CI 0.51-0.90, p = 0.008). Cage obliquity was inversely correlated with cage-rim contact ratio (ρ = -0.370; p < 0.001) and mediolateral contact spread (ρ = -0.457; p < 0.001), but not with contact centroid. Fusion, radiographic correction loss, and patient-reported outcomes did not differ significantly by subsidence status. CONCLUSIONS: In this single-design cohort, greater residual cage obliquity and reduced cage-rim contact ratio were associated with subsidence, identifying insufficient rotation and reduced effective anterior rim support as potentially modifiable technical factors. These findings provide a rationale for developing and prospectively evaluating intraoperative methods to assess cage rotation and optimize rim support, although the optimal rotational target and its preventive effect require further validation.
Abstract as published, via PubMed.
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