Computational comparison of three posterior lumbar interbody fusion techniques by using porous titanium interbody cages with 50% porosity

Published Date
1 April 2016, Vol.71:35–45, doi:10.1016/j.compbiomed.2016.01.024

Author 

• Yung-Heng Lee ^a
• Chi-Jen Chung ^b
• Chih-Wei Wang ^c,d
• Yao-Te Peng ^d,e
• Chih-Han Chang ^d
• Chih-Hsien Chen ^d,f
• Yen-Nien Chen ^d,e,,
• Chun-Ting Li ^g,,

• aDepartment of Orthopaedic, Ministry of Health and Welfare Feng Yuan Hospital, Taichung City, Taiwan
• bDepartment of Dental Technology and Materials Science, Central Taiwan University of Science and Technology, Taichung City, Taiwan
• cDepartment of Mechanical Engineering, University of Washington, Seattle City, WA, USA
• dDepartment of BioMedical Engineering, National Cheng Kung University, Tainan City, Taiwan
• eMetal Industries Research & Development Centre, Kaohsiung City, Taiwan
• fDepartment of Orthopaedic Surgery, Tainan Municipal Hospital, Tainan City, Taiwan
• gGraduate Institute of Mechatronic System Engineering, National University of Tainan, Tainan City, Taiwan

Received 10 September 2015. Accepted 22 January 2016. Available online 3 February 2016. 

Highlights

• A numerical model containing porous cages and a lumbar segment was developed.
• •
  The bone tissue ingrowth into the pores of the cage is considered.
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  Bone fusion enhances the stability of the lumbar segment with a porous cage.
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  Bone fusion also reduces the peak von Mises stress in the cortical bone and porous cage.

Abstract

This study investigated the biomechanical response of porous cages and lumbar spine segments immediately after surgery and after bone fusion, in addition to the long-term effects of various posterior lumbar interbody fusion (PLIF) techniques, by using the finite element method. Lumbar L3-L4 models based on three PLIF techniques (a single cage at the center of the intervertebral space, a single cage half-anterior to the intervertebral space, and two cages bilateral to the intervertebral space) with and without bone ingrowth were used to determine the biomechanical response of porous cages and lumbar segments instrumented with porous titanium cages (cage porosity=50%, pore diameter=1 mm). The results indicated that bone fusion enhanced the stability of the lumbar segments with porous cages without any posterior instrumentation and reduced the peak von Mises stress in the cortical bones and porous cages. Two cages placed bilateral to the intervertebral space achieved the highest structural stability in the lumbar segment and lowest von Mises stress in the cages under both bone fusion conditions. Under identical loading (2-N m), the range of motion in the single cage at the center of the intervertebral space with bone fusion decreased by 11% (from 1.18° to 1.05°) during flexion and by 66.5% (from 4.46° to 1.5°) during extension in the single cage half-anterior to the intervertebral space with bone fusion compared with no-fusion models. Thus, two porous titanium cages with 50% porosity can achieve high stability of a lumbar segment with PLIF. If only one cage is available, placing the cage half-anterior to the intervertebral space is recommended for managing degenerated lumbar segments.

Keywords

Porous interbody cage

Finite element method

Posterior lumbar interbody fusion

Bone ingrowth

Lumbar L3-4

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• ⁎ 
  Corresponding author at: Department of BioMedical Engineering, National Cheng Kung University, Tainan City, Taiwan.
• ⁎⁎ 
  Corresponding author at: Graduate Institute of Mechatronic System Engineering, National University of Tainan, Tainan City, Taiwan.

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