Kinematic analyse of mobile type artificial disc replacement

The objective of this study is to develop a detailed three-dimensional geometrically and biomechanically accurate finite element model of the human lower cervical spine (C4-C6), and applied to determination of movement of the mobile type artificial disc replacement Prodisc-C made by Synthes. 3D (FE) model of the multi-level cervical spine was consists of three vertebrae and two intervertebral discs. Ligaments were preserved and simulated by non-linear contact elements. The complex model of the spine was created by using computer tomography (CT) images and STL-CAD method. The entire meshing procedure for the spinal partitions was significantly speeded up by combining 3D tetrahedral elements with conversion surfaces elements to elements of volume. For the validation againts published data was used an intact spinal segment loaded by 1 mm axial dispacement, 1,5 Nm in directions flexion/extension. Further, the commercial replacement was possitioned between C4-C5. Flexion, extension, right/left lateral bending and axial displacement loading conditions were used. Presented study compared range of motion (ROM) and stability of the lower cervical spine 1. intact 2. implanted spine (without ALL). The results achieved have a large medical gain in neurology and spine surgery.