title: Determination of the translational and rotational stiffnesses of an L4-L5 functional spinal unit using a specimen-specific finite element model.
abstract: The knowledge of spinal kinematics is of paramount importance for many aspects of clinical application (i.e. diagnosis, treatment and surgical intervention) and for the development of new spinal implants. The aim of this study was to determine the translational and rotational stiffnesses of a functional spinal unit (FSU) L4-L5 using a specimen-specific finite element model. The results are needed as input data for three-dimensional (3D) multi-body musculoskeletal models in order to simulate vertebral motions and loading in the lumbar spine during daily activities. Within the modelling process, a technique to partition the constitutive members and to calibrate their mechanical properties for the complex model is presented. The material and geometrical non-linearities originating from the disc, the ligaments and the load transfer through the zygapophysial joints were considered. The FSU was subjected to pure moments and forces in the three anatomical planes. For each of the loading scenarios, with and without vertical and follower preload, the presented technique provides results in fair agreement with the literature. The novel representation of the nonlinear behaviour of the translational and rotational stiffness of the disc as a function of the displacement can be used directly as input data for multi-body models.
authors: Laboratory for Mechanical Systems Engineering, Empa Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland. bernhard.weisse@empa.ch
authors: B
authors: B
authors: Weisse
authors: A K
authors: AK
authors: Aiyangar
authors: Ch
authors: Ch
authors: Affolter
authors: R
authors: R
authors: Gander
authors: G P
authors: GP
authors: Terrasi
authors: H
authors: H
authors: Ploeg
mesh_terms: D001696:Biomechanical Phenomena; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008297:Male; D055595:Mechanical Phenomena; D012399:Rotation; D013131:Spine / Q000033:anatomy & histology / Q000502:physiology; D016474:Weight-Bearing