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Biomechanical Comparison of Transforaminal Lumbar Interbody Fusion With 1 or 2 Cages by Finite-Element Analysis

Xu, Hao MD; Ju, Wen MD; Xu, Neng MD; Zhang, Xiaojian MD; Zhu, Xiaodong MD; Zhu, LiFan MD; Qian, Xuefeng MD; Wen, Fengbiao MD; Wu, Weidong MD; Jiang, Fugui MD

doi: 10.1227/01.neu.0000430320.39870.f7
Instrumentation and Technique

BACKGROUND: Anterior lumbar interbody fusion and posterior lumbar interbody fusion with 1 cage have been shown to have similar biomechanics compared with the use of 2 cages. However, there have been no reports on the biomechanical differences between using 1 or 2 cages in transforaminal lumbar interbody fusion (TLIF) surgery.

OBJECTIVE: To determine the biomechanical differences between the use of 1 or 2 cages in TLIF by finite-element analysis.

METHODS: Three validated finite-element models of the L3-L5 lumbar segment were created (intact model and single- and paired-cage TLIF models). To study the biomechanics, a compressive preload of 400 N over 7.5 N-m was applied to the superior surfaces of the L3 vertebral body to simulate flexion, extension, rotation, and lateral bending.

RESULTS: There was no significant difference in the range of motion between single-cage and paired-cage TLIF models, < 1° for all loading cases. Cage stress was high in the single-cage TLIF model under all loading conditions. Bone graft stress was high in the single-cage TLIF model. Pedicle screw stress was higher in the single-cage compared with the paired-cage TLIF.

CONCLUSION: Single-cage TLIF approximates biomechanical stability and increases the stress of the bone graft. The use of a single cage may simplify the standard TLIF procedure, shorten operative times, decrease cost, and provide satisfactory clinical outcomes. Thus, single-cage TLIF is a useful alternative to traditional 2-cage TLIF.

ABBREVIATIONS: FEM, finite-element model

PLIF, posterior lumbar interbody fusion

TLIF, transforaminal lumbar interbody fusion

Department of Orthopaedics, the First Hospital of Wujiang, Jiangsu Province, People’s Republic of China

Correspondence: Fugui Jiang, MD, or Neng Xu, MD, Department of Orthopaedics, First Hospital of Wujiang, Jiangsu Province, Gongyuan Rd, Wujiang 215000, People’s Republic of China. E-mail: xuhaomouse2004@sina.com or xuhaomouse20041@sina.com

* These authors have contributed equally to this article.

Received September 21, 2012

Accepted May 06, 2013

Copyright © by the Congress of Neurological Surgeons