Preliminary Measurements of Lumbar Spine Kinematics and Stiffness

The purpose of the presented study was the experimental measurement of lumbar spine stiffness and its range of motion. The dependence of torsion moment of lumbar spine segment on deflection of flexion, extension and torsion was observed during experiments. Stiffness of spine segment was determined from measured data. Human lumbar spine was used for verification of the experimental technique. The sample consisted of one lumbar vertebrae composed by five vertebral bodies and four intervertebral discs. All muscles were removed, however all ligaments were preserved. Experiments were carried out on the test system MTS 858.2 MiniBionix, where loading by axial force and torsion moment is possible at the same time. Special Modular Bionix Spine Test Fixator, attached to the test system was used for the measurements. Loading was controlled kinematically (gradual turning) by keeping the axial force equal zero. Measurement was time-dependent. The results of these experiments are going to be used as input data for creating a model of artificial lumbar spine and new type of artificial disc replacement.