Osteolitic vs Osteoblastic metastatic lesion: Computational modeling of fracture risk in the human vertebra after screws fixation procedure

<p>Metastatic lesions compromise the mechanical integrity of vertebrae, increasing the&nbsp;fracture risk. Screwfixation is usually performed to guarantee spinal stability and prevent dramatic fracture events. Accordingly, predicting the overall mechanical response in such conditions is&nbsp;critical to planning and optimizing the surgical treatment. This work proposes an image-basedfinite element computational approach describing the mechanical behavior of a patient-specific instrumented metastatic vertebra by assessing the effect of lesion size, location, type and shape&nbsp;on the fracture load and fracture patterns under physiological loading conditions. A specific&nbsp;constitutive model for the metastasis is integrated to account for the effect of the diseased tissue&nbsp;on the bone material properties. Computational results demonstrate that size, location, and type&nbsp;of metastasis significantly affect the overall vertebral mechanical response, and suggest better account these parameters in estimating the fracture risk. Combining multiple osteolytic lesions to&nbsp;account for irregular shape of the overall metastatic tissue has a not significant effect on fracture&nbsp;load of vertebra macroscopically. In addition, the combination of loading mode and metastasis&nbsp;type is shown for the first time as a critical modeling parameter in determining the fracture risk.&nbsp;The proposed computational approach moves towards defining a clinically integrated tool to&nbsp;improve the management of metastatic vertebrae and quantitatively evaluate fracture risk.</p>