Structural parameters determining the strength of the porcine vertebral body affected by tumours

Abstract

Spinal metastatic disease could lead to catastrophic consequences for the patient. However, the structural parameters that explain the weakening of vertebrae affected by tumours are not fully understood. In this study, we developed a specimen-specific finite element model to predict the strength of the porcine vertebra with simulated tumours and used it to find the structural parameters determining the strength. We validated our model with mechanical testing and then we analysed the compressive strength of intact vertebrae and seven defects with different size and shape. The results showed that the minimum bone mineral mass of the cross section and areal defect fraction were the best predictors of the normalized strength. We also found that areal parameters appeared to be better predictors than the volumetric ones. In conclusion, reduction in bone strength for vertebrae weakened by metastatic tumours is mostly associated with decrease in the mechanical properties of the cross section.

A Novel Modelling Methodology Which Predicts the Structural Behaviour of Vertebral Bodies under Axial Impact Loading: A Finite Element and DIC Study

“…In this preliminary calibration phase, each sample was subjected to a quasi-static loading ramp and values obtained for experimental and numerical stiffness were compared, resulting in average values within 1% of each other, 8909 ± 2156 and 8936 ± 2121 , respectively. In comparison with studies which used human lumbar VBs (the largest dataset in the literature), the values of stiffness obtained here were either similar [ 61 , 62 , 63 , 64 , 65 ] or smaller [ 53 , 66 , 67 , 68 ].…”

Properties of PMMA end cap holders affect FE stiffness predictions of vertebral specimens

“…This study investigated the effect of the material properties assigned to cement end caps on FE models aimed at predicting the response of a vertebral body construct to quasi-static loading. FE is widely used in biomechanical investigations and recent studies have focused on the determination of the right approach to describe the material properties of the biological elements of said models, such as cancellous bone, cartilage, etc [32][33][34][35][36][37][38] ; much less attention has been paid to other elements comprising the models, such as cement end caps. Cement end caps are widely used in experimental spine biomechanics studies [3][4][5] ; this practice arises from the desire of aligning the vertical axis of vertebral bodies, typically characterised by awkward geometries, to the line of action of the applied force and avoiding point loading.…”

“…This study investigated the effect of the material properties assigned to cement end caps on FE models aimed at predicting the response of a vertebral body construct to quasi-static loading. FE is widely used in biomechanical investigations and recent studies have focused on the determination of the right approach to describe the material properties of the biological elements of said models, such as cancellous bone, cartilage, etc 32 – 38 ; much less attention has been paid to other elements comprising the models, such as cement end caps.…”

Inducing targeted failure in cadaveric testing of 3-segment spinal units with and without simulated metastases

“…In such experiments, cadaveric vertebral bones are mechanically loaded until failure. In previous in vitro studies, vertebral strength has mostly been established via experiments using single vertebral bodies [5][6][7][8] , single vertebrae [9][10][11][12] , and functional spinal units [13] . However, the simplified loading con-ditions applied to one vertebra (or just its body) are bound to introduce loading artifacts.…”