Biomechanical performance evaluation of composite metamaterial implant with 3D printing approach for lumbar interbody fusion surgery: A finite element study

Stiffer implants restrict micromotions of the spine and load transfer to the bone grafts which may cause stress shielding, and adjacent segment degeneration (ASD). This study investigates the biomechanical performance of traditional cages and rods made of polyetheretherketone (PEEK), carbon-fiber-reinforced PEEK composite (CPEEK), titanium alloy (Ti), and metamaterial rods made of CPEEK. Finite element models of L4-L5 vertebral bodies, pedicle screws, and cages were modeled to simulate the biomechanical performances of different stiffness cages and rods under bending, extension, flexion, and torsion loads. Results revealed that dense Ti cages and rods generated higher stresses at cancellous bone and cages and lower stresses in bone grafts. However, metamaterial CPEEK rods and cages helped to share the load with bone grafts at the anterior and posterior sides, provided higher flexibility to avoid ASD, and left lesser stresses on the cancellous bone to prevent cage subsidence.

Automated summary

This study investigates the biomechanical performance of different implants made of various materials for spinal repair. The results demonstrate that metamaterial CPEEK rods and cages have better performance and can avoid some complications and issues.