title: Diurnal variations in intervertebral disc height affect spine flexibility, intradiscal pressure and contact compressive forces in the facet joints.
abstract: Diurnal changes of intervertebral disc height are caused by high compressive loading during the day, which expulses fluid from the disc, and by osmotic pressure, which imbibes fluid into the disc at low loading. The aim of the present study was to determine the magnitude of diurnal changes in spine flexibility, intradiscal pressures and contact forces in the facet joints. A validated osseoligamentous finite element model of the lumbar spine was used to determine these quantities for morning and evening situations. Disc height varied by 10% for these two situations. Spine flexibility and facet joint forces were markedly higher in the evening than in the morning. Intradiscal pressures were higher in the morning than in the evening. The different spine flexibilities in the morning and evening should be taken into account during kinematic measurements. Predicted facet joint forces may be used for the designing and pre-clinical testing of artificial facet joint replacements.
authors: Julius Wolff Institut, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
authors: Thomas
authors: T
authors: Zander
authors: Pushpanjali
authors: P
authors: Krishnakanth
authors: Georg
authors: G
authors: Bergmann
authors: Antonius
authors: A
authors: Rohlmann
mesh_terms: D002940:Circadian Rhythm; D020342:Finite Element Analysis; D006801:Humans; D007403:Intervertebral Disc / Q000033:anatomy & histology*; D013131:Spine / Q000502:physiology*