Bone Remodelling in Lumbar Spine: A Comparative Analysis of Ti-Alloy, PEEK and CFR-PEEK Implant Materials

Long-term performance-based study to comprehend the biomechanics of Ti-6Al-4V, PEEK and CFR-PEEK implant materials in fusing a lumbar spine is not available in literature. The present study investigates the performance of these implant materials in fusing an L4-L5 segment by executing a strain energy density-based bone remodelling theory. The FE models of intact and implanted lumbar spines were reconstructed from computed tomography scan images and simulated for 500 N compressive load and a combination of 150 N preload and 10 Nm moment. The models attained equilibrium state when the apparent bone density change became less than 0.005 g cm^-3 between two consecutive iterations. The implanted models' range of motion (ROM) has been reduced by 73%-85% for Ti-6Al-4V, 64%-78% for PEEK and 69%-81% for CFR-PEEK implanted models. All models exhibit a substantial rise in bone density (30%) in the implant-bone interface region and cancellous bone. However, the CFR-PEEK implanted model exhibited a bone density loss of only 0%-0.3%, compared to the Ti-6Al-4V implanted model (0.3%-6.7%) and the PEEK model (1.5%-30%). The findings indicate that CFR-PEEK material may be a better implant material than PEEK and Ti-6Al-4V while considering bone density distributions and equivalent strains from immediate post-operative to equilibrium conditions.