Biomechanical effects of anterior cervical plate on caged C5-C6 construct

The objective of this study is to analyze the internal biomechanical influences of titanium and absorbable poly-levo-lactide (PLLA) anterior cervical plate (ACP) augmentation on the caged C5-C6 segment. A 3D finite element model of caged C5-C6 with a constrained ACP supplementary fixation was simulated. Internal parameters of the titanium and PLLA ACP were analyzed and compared with those in the C5-C6 model implanted with cage alone. The results showed that the titanium and PLLA ACPs greatly reduced the maximum compressive displacement; the maximum von Mises stress on the C6 superior endplate, and the maximum von Mises stress in the cortical wall and cancellous core at the level immediately inferior to the superior screws were also greatly decreased. The maximum contact pressures at the interfaces between the cage and the C6 superior endplate for the titanium and PLLA plate were respectively reduced by 82.29% and 80.12% compared to the cage alone. The clinical relevance of the study is that both the titanium and PLLA ACPs can provide sufficient initial rigidity which is needed for the spinal fusion. With the consideration of its unique bioabsorbability, the PLLA ACP is more desirable for a more successful fusion rate and lower clinical complication.Yang Kai, Teo Ee Chon and Fuss Franz Konstanti