Abstract:
This study used a non-linear 3-D finite element model of a cadaveric L3-L4 spinal motion segment to investigate how the positioning of a total disc replacement (TDR) implant, specifically the ProDisc-L, affects biomechanical outcomes like facet contact forces (FCFs), vertebral body strains, and range of motion (RoM). The goal was to understand the biomechanical factors contributing to common TDR complications like implant subsidence and facet arthrosis. The TDR was modeled in two positions, "posterior" and "anterior," along the sagittal midline. The models were subjected to various loads simulating flexion, extension, axial rotation, and lateral bending. The results showed that TDR implantation generally increased FCFs and RoM, regardless of implant placement, suggesting a greater dependence on the facets to limit motion. The findings indicate that the increased loading on facet joints due to greater mobility may lead to facet arthrosis. Furthermore, high von Mises (VM) strains, particularly around the edges of the implant, were observed in both anterior and posterior TDR placements during flexion and extension. These high strains suggest that activities involving spinal flexion could contribute to implant subsidence and anterior migration. The study concludes that both implant subsidence and facet arthrosis may be consequences of increased joint mobility after TDR, highlighting the critical role of biomechanics in post-surgical complications.
