title: Modelling and simulation of the intervertebral movements of the lumbar spine using an inverse kinematic algorithm.
abstract: An inverse kinematic model is presented that was employed to determine the optimum intervertebral joint configuration for a given forward-bending posture of the human trunk. The lumbar spine was modelled as an open-end, kinematic chain of five links that represented the five vertebrae (L 1-L5). An optimisation equation with physiological constraints was employed to determine the intervertebral joint configuration. Intervertebral movements were measured from sagittal X-ray films of 22 subjects. The mean difference between the X-ray measurements of intervertebral rotations in the sagittal plane and the values predicted by the kinematic model was less than 1.6 degrees. Pearson product-moment correlation R was used to measure the relationship between the measured and predicted values. The R-values were found to be high, ranging from 0.83 to 0.97, for prediction of intervertebral rotation, but poor for intervertebral translation (R= 0.08-0.67). It is concluded that the inverse kinematic model will be clinically useful for predicting intervertebral rotation when X-ray or invasive measurements are undesirable. It will also be useful to biomechanical modelling, which requires accurate kinematic information as model input data.
authors.affiliation: Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong.
authors.forename: L W
authors.initials: LW
authors.lastname: Sun
authors.forename: R Y W
authors.initials: RY
authors.lastname: Lee
authors.forename: W
authors.initials: W
authors.lastname: Lu
authors.forename: K D K
authors.initials: KD
authors.lastname: Luk
mesh_terms: D000465:Algorithms; D001696:Biomechanical Phenomena; D006801:Humans; D007596:Joints / Q000502:physiology; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000502:physiology*; D008433:Mathematics; D008954:Models, Biological; D009068:Movement / Q000502:physiology*; D011187:Posture / Q000502:physiology; D011859:Radiography; D012371:Robotics; D012399:Rotation