Luigi La Barbera1,2, Fabio Galbusera3, Hans-Joachim Wilke4, Tomaso Villa5,3. 1. Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milan, Italy. luigi.labarbera@polimi.it. 2. IRCCS Galeazzi Orthopaedic Institute, via Riccardo Galeazzi 4, 20161, Milan, Italy. luigi.labarbera@polimi.it. 3. IRCCS Galeazzi Orthopaedic Institute, via Riccardo Galeazzi 4, 20161, Milan, Italy. 4. Institute of Orthopaedic Research and Biomechanics, Centre of Musculoskeletal Research Ulm, Ulm University, Helmholtzstrasse 14, 89081, Ulm, Germany. 5. Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milan, Italy.
Abstract
PURPOSE: To discuss whether the available standard methods for preclinical evaluation of posterior spine stabilization devices can represent basic everyday life activities and how to compare the results obtained with different procedures. METHODS: A comparative finite element study compared ASTM F1717 and ISO 12189 standards to validated instrumented L2-L4 segments undergoing standing, upper body flexion and extension. The internal loads on the spinal rod and the maximum stress on the implant are analysed. RESULTS: ISO recommended anterior support stiffness and force allow for reproducing bending moments measured in vivo on an instrumented physiological segment during upper body flexion. Despite the significance of ASTM model from an engineering point of view, the overly conservative vertebrectomy model represents an unrealistic worst case scenario. A method is proposed to determine the load to apply on assemblies with different anterior support stiffnesses to guarantee a comparable bending moment and reproduce specific everyday life activities. CONCLUSIONS: The study increases our awareness on the use of the current standards to achieve meaningful results easy to compare and interpret.
PURPOSE: To discuss whether the available standard methods for preclinical evaluation of posterior spine stabilization devices can represent basic everyday life activities and how to compare the results obtained with different procedures. METHODS: A comparative finite element study compared ASTM F1717 and ISO 12189 standards to validated instrumented L2-L4 segments undergoing standing, upper body flexion and extension. The internal loads on the spinal rod and the maximum stress on the implant are analysed. RESULTS: ISO recommended anterior support stiffness and force allow for reproducing bending moments measured in vivo on an instrumented physiological segment during upper body flexion. Despite the significance of ASTM model from an engineering point of view, the overly conservative vertebrectomy model represents an unrealistic worst case scenario. A method is proposed to determine the load to apply on assemblies with different anterior support stiffnesses to guarantee a comparable bending moment and reproduce specific everyday life activities. CONCLUSIONS: The study increases our awareness on the use of the current standards to achieve meaningful results easy to compare and interpret.
Keywords:
ASTM F1717; Anterior support; Finite element; ISO 12189; Preclinical evaluation; Spine stabilization; Standard
Authors: George Sapkas; Konstantinos Kateros; Stamatios A Papadakis; Emmanouel Brilakis; George Macheras; Pavlos Katonis Journal: Open Orthop J Date: 2010-01-15
Authors: Justin S Smith; Christopher I Shaffrey; Christopher P Ames; Jason Demakakos; Kai-Ming G Fu; Sassan Keshavarzi; Carol M Y Li; Vedat Deviren; Frank J Schwab; Virginie Lafage; Shay Bess Journal: Neurosurgery Date: 2012-10 Impact factor: 4.654
Authors: Luigi La Barbera; Alessandro Cianfoni; Andrea Ferrari; Daniela Distefano; Giuseppe Bonaldi; Tomaso Villa Journal: Front Bioeng Biotechnol Date: 2019-10-25