Comparisons of Biomechanical Properties of Intact and Implanted Level in Pedicle Section of Patient-Specific Cervical Spine: An In-Silico Study

Cervical pedicle screw-rod fixation is a challenging technique for spinal surgery due to its ability to provide better stabilization of the spine in treating traumatic injuries, degenerative changes, and orthopaedic and oncological diseases. Pedicle screw-rod fixation can increase the mechanical strength of the spine by using small diameter screw implants that are accurately placed. Pedicle screw has minimally invasive techniques, which results in smaller incisions and less pain for the patient. The goal of this research is to comprehend the comparisons of Range of motion (ROM), stress on the implant and the bone next to it of screw-rod in pedicle section of cervical spine during loadings of flexion–extension. CT scan data is used to develop a 3-D cervical spine FE model (C2–C7 vertebrae), pedicle screw is formed in SOLIDWORKS and single level pedicle screw-rod fixation at C5–C6 vertebrae is used in ANSYS 17.2. C2 vertebrae are subjected to a 53-N compressive force and a 1-Nm moment, and C7 is fixed. The ROM is reduced by 78% at C5-C6 level for screw-rod compared with intact spine during flexion–extension loading conditions. The ROM slightly increases at the adjacent levels of cervical spine. During the flexion–extension of pedicle screw-rod, the highest stresses developed in PEEK screw-rod implants range from 21 to 26 MPa, these values fall below the yield stress of the material. The pedicle screw-rod operation decreased range of motion at fixation segment and increased ROM to some extent at adjacent segment for flexion–extension motions as compared to intact cervical spine.