Biomechanical investigation of extragraft bone formation influences on the operated motion segment after anterior cervical spinal discectomy and fusion

Abstract

Although the clinical importance of extragraft bone formation (ExGBF) and bridging (ExGBB) has been reported, few studies have investigated the biomechanical influences of ExGBF on the motion segment. In this study, ExGBF was simulated at the C5-C6 motion segment after anterior cervical discectomy and fusion using a developed finite element model and a sequential bone-remodelling algorithm in flexion and extension. The computer simulation results showed that extragraft bone was primarily formed in the extension motion and grew to form ExGBB. A stepwise decrease in the intersegmental rotation angle, maximum von Mises stress and strain energy density on the trabecular bone with ExGBF were predicted in extension. When ExGBB was formed in the trabecular bone region, the intersegmental rotation angle slightly decreased with additional bone formation. However, the stress and strain energy density on the trabecular bone region decreased until ExGBB reached the peripheral cortical margin. The results offer a rationale supporting the hypothesis that mechanical stimuli influence ExGBF. ExGBF was helpful in increasing the stability of the motion segment and decreasing the fracture risk of trabecular bones, even in cases in which ExGBB was not formed. ExGBB can be classified as either soft or hard bridging based on a biomechanical point of view.

Biomechanical Evaluation of Intervertebral Fusion Process After Anterior Cervical Discectomy and Fusion: A Finite Element Study

“…They found that the average change in interbody force magnitude from full extension to full flexion decreased significantly during fusion. Furthermore, Park and Jin (2019 ) and Jin and Park (2021 ) simulated extragraft bone formation at the C5–C6 motion segment after ACDF using a developed finite element model and a sequential bone-remodeling algorithm in flexion and extension. The results suggested that both the stress and strain energy density slightly changed in flexion while a significantly stepwise decrease was predicted in extension until the fusion was terminated ( Park and Jin, 2019 ).…”

“…Furthermore, Park and Jin (2019 ) and Jin and Park (2021 ) simulated extragraft bone formation at the C5–C6 motion segment after ACDF using a developed finite element model and a sequential bone-remodeling algorithm in flexion and extension. The results suggested that both the stress and strain energy density slightly changed in flexion while a significantly stepwise decrease was predicted in extension until the fusion was terminated ( Park and Jin, 2019 ). Therefore, more attention should be paid to the stress distribution of interbody implant in extension because of the significant changes during fusion.…”

Comparison of Extragraft Bone Formation after Anterior Cervical Discectomy and Fusion Using Simultaneous and Sequential Algorithms

“…Thus, degenerative and traumatic diseases are observed most frequently in the motion segment [17,18], and it was chosen to simulate extragraft bone formation in this study. A validated finite element (FE) model of the osteoligamentous C5-C6 motion segment was used ( Figure 1) [19], which was developed using anonymised computed tomographic images collected from the Catholic Digital Human Library (Approval No. CUMC10U161, IRB, College of Medicine, The Catholic University of Korea).…”

Which is the better posterior lumbar dynamic device: Dynesys or BioFlex?

“…The movements and the axial pre-compression forces were loaded onto L3. By using frictionless contact, the facet joints were simulated [12]. To verify the intact model, a comparison of the predicted results with those reported in the literature was performed.…”