Modelling and simulation of the intervertebral movements of the lumbar spine using an inverse kinematic algorithm

L.W. Sun, R.Y.W. Lee, W. Lu, K.D.K. Luk

Research output: Contribution to journalArticlepeer-review


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 (L1-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 . 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 (H = 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.
Original languageEnglish
Pages (from-to)740-746
Number of pages7
JournalMedical & Biological Engineering & Computing
Issue number6
Publication statusPublished - Nov 2004


  • Optimisation
  • Intervertebral motion
  • Lumbar spine
  • Inverse kinematics


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