title: Does disc space height of fused segment affect adjacent degeneration in ALIF? A finite element study.
abstract: OBJECTIVE
  The restoration of disc space height of fused segment is essential in anterior lumbar interbody fusion, while the disc space height in many cases decreased postoperatively, which may adversely aggravate the adjacent segmental degeneration. However, no literature available focused on the issue.
  
  
  METHODS
  A normal healthy finite element model of L3-5 and four anterior lumbar interbody fusion models with different disc space height of fused segment were developed. 800 N compressive loading plus 10 Nm moments simulating ﬂexion, extension, lateral bending and axial rotation were imposed on L3 superior endplate. The intradiscal pressure, the intersegmental rotation, the tresca stress and contact force of facet joints in L3-4 were investigated.
  
  
  RESULTS
  Anterior lumbar interbody fusion with severely decreased disc space height presented with the highest values of the four parameters, and the normal healthy model presented with the lowest values except, under extension, the contact force of facet joints in normal healthy model is higher than that in normal anterior lumbar interbody fusion model. With disc space height decrease, the values of parameters in each anterior lumbar interbody fusion model increase gradually.
  
  
  CONCLUSIONS
  Anterior lumbar interbody fusion with decreased disc space height aggravate the adjacent segmental degeneration more adversely.
authors.affiliation: Jinan University, Medical School, Department of Traditional Chinese Medicine, Guangzhou, China. wkdd2009@hotmail.com
authors.forename: Shujie
authors.initials: S
authors.lastname: Tang
authors.forename: Xueying
authors.initials: X
authors.lastname: Meng
mesh_terms: D000328:Adult; D019412:Anatomy, Cross-Sectional; D001696:Biomechanical Phenomena; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006801:Humans; D007403:Intervertebral Disc / Q000473:pathology*; D008297:Male; D008953:Models, Anatomic; D017711:Nonlinear Dynamics; D016012:Poisson Distribution; D013123:Spinal Fusion; D013131:Spine / Q000033:anatomy & histology / Q000473:pathology; D013314:Stress, Mechanical; D021801:Zygapophyseal Joint / Q000033:anatomy & histology