title: Influence of ligament stiffness on the mechanical behavior of a functional spinal unit.
abstract: Data on the stiffnesses of spinal ligaments are required for analytical studies on the mechanical behavior of spinal segments. Values obtained experimentally vary widely in the literature. A finite element model of an L3/L4 functional spinal unit was used to determine the influence of ligament stiffness on intersegmental rotation and forces in the ligaments. The lowest values for ligament stiffness selected from the literature were used in one set of calculations, and the highest values were simulated in a second set. The nonlinear model was loaded with pure moments of 7.5 and 15 Nm in the three main anatomical planes. The mechanical behavior of the functional spinal unit was strongly influenced by ligament stiffness. In some cases, a ligament with low stiffness does not carry any load, while the same ligament with high stiffness has to carry a high load. This indicates that finite element models of spinal segments have to be validated and that a realistic quantitative prediction of ligament forces is extremely difficult.
authors.affiliation: Biomechanics Laboratory, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203 Berlin, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Zander
authors.forename: Antonius
authors.initials: A
authors.lastname: Rohlmann
authors.forename: Georg
authors.initials: G
authors.lastname: Bergmann
mesh_terms: D001696:Biomechanical Phenomena; D006801:Humans; D008022:Ligaments / Q000503:physiopathology*; D008159:Lumbar Vertebrae / Q000503:physiopathology*