3D PARAMETRIC FINITE ELEMENT MODELLING OF METASTATIC VERTEBRAE: INSIGHTS ON BONE-LESION INTERFACE

Bone metastases are a common complication in cancers such as prostate, lung, and breast, significantly increase the risk of vertebral fractures, particularly in the spine, where 70% of bone metastases occur. Clinical soring systems are used but are not sensitive and specific enough. Computational modelling can be helpful for investigating how metastatic lesions affect the stability of the spine. This study developed a 3D parametric finite element (FE) model for patient-specific analyses, validated using ex vivo data from, enabling the exploration of vertebral parameters and the biomechanical role of the bone-tumour interface. A 3D parametric FE model was developed using Python scripting in Abaqus. The model included two vertebrae separated by an intervertebral disc: one representing a healthy vertebra (control) and the other simulating a vertebra affected by metastatic lesions. Distinctions were made between cortical and trabecular bone. As a first approximation, all materials were assumed to be homogeneous, isotropic and linearly elastic. This framework allowed customization of vertebral geometry, cortical thickness, intervertebral disc thickness, and lesion size and position based on medical imaging, facilitating realistic and patient-specific studies. The study focused on two types of lesions: lytic and blastic. Bonded and debonded bone-lesion interfaces were simulated using tie constraints and frictionless contact, respectively. Additionally, an inverse problem-solving algorithm was developed to explore intermediate bonding conditions, where the interface exhibits partial bonding. The bone-lesion interface significantly affected vertebral biomechanics based on bonding conditions, particularly in blastic lesions, which modified their behaviour depending on the state of the interface. In contrast, lytic lesions were largely unaffected by interface states, suggesting a predominantly debonded condition. These results were supported by the inverse problem algorithm, which provided information on the different degrees of adhesion as a function of damage. Material properties and bone-lesion interface conditions are crucial in vertebral response to metastatic lesions. This parametric FE model highlighted the importance of considering intermediate bonding scenarios for blastic lesions. Further studies are necessary to fully characterize bone-lesion interfaces and their biomechanical implications. Acknowledgements. METASTRA project funded by the European Union HEU topic HLTH-2022-12-01 grant 101080135