EXPERIMENTAL ANALYSIS OF THE LUMBAR SPINE KINEMATICS

Pain-provoking disorders of the lumbar spine affect most of adult population and nearly everyone suffers from some of them during their lifetime. A common symptom of diseases, injuries or inevitable changes in the area of lumbar spine is known as the Low Back Pain (LBP). A chronic form of the LBP, called the Low Back Pain syndrome, is mostly caused by degenerative changes of intervertebral discs of the lowest intervertebral joints. The work was focused on in vitro analysis of the porcine lumbar spine kinematics. Two last neighbouring intervertebral joints without active tissue, L4/5 and L5/6, were used. The total number of fifteen cadaveric samples of porcine lumbar spine was involved. A unique loading mechanism was designed and constructed for the purposes of this study. Samples were loaded by flexion/extension movement within the physiological range of motion of ± 5°, in a quasi-static mode. The recording and analysing of the lumbar spine kinematics was realized by the motion capture camera system (Qualisys AB, G？teborg, Sweden). The results showed that the so-called instantaneous axis of rotation (IAR), or the corresponding instantaneous centre of rotation (ICR), was an adequate objective parameter for the assessment of the lumbar spine kinematics. Its position was comparable across all samples and situated very close to the spinal canal. For the purposes of this work, an altered artificial disc of a ball-and-socket type (ProSpon, Ltd., Kladno, Czech Republic) was used to study the kinematics of two neighbouring joints after the disc replacement in the area of a caudally situated one. The results of this comparative analysis showed a significant influence of the artificial disc on the kinematics of both, caudally situated joint, where the disc was implanted, and the adjacent one