Comparative analysis of lumbar spine reconstruction using implants made of homogeneous PEEK and lattice

Despite significant advances in neurosurgery, stable spinal reconstruction after total en bloc spondylectomy (TES) remains a challenge. This procedure standardly consists of replacing the vertebra with an implant and performing transpedicular fixation. However, standard serial implants do not always provide sufficient support and adequate load distribution, increasing the risks of instability, deformations and subsidence of the implant. It is therefore crucial to develop customized implants based on additive technologies. Three different implants were examined in this study: two polymeric implants made of homogeneous polyetheretherketone (PEEK) with posterior and lateral fixation and an additively manufactured implant made of titanium-based lattice meta-biomaterial with lateral fixation. Calculations of the stress–strain state of the reconstructed spine were performed for each of them for six basic actions: flexion, extension, right bending, left bending, right rotation and left rotation. Our findings indicate that the polymeric implant with posterior fixation might be the best candidate of all the implants considered, inducing the lowest stresses in bony endplates. Additionally, this type of implant ensures the stability of transpedicular fixation. On the other hand, while the metamaterial implant also offers certain advantages, the technique for anchoring the implant to the vertebrae should be further refined to prevent the implant's deformation and loosening.