Effects of Breast and Prostate Cancer Metastases on Lumbar Spine Biomechanics: Rapid In Silico Evaluation

Metastases to distant organs are a frequent occurrence in cancer diseases. The skeletal system, especially the spine, is one such organ. The objective of this study was to apply a numerical modeling, using a finite element method (FEM), for the evaluation of deformation and stress in lumbar spine in bone metastases to the spine. We investigated 20 patients (10 women and 10 men) aged 38-81 years. In women, osteolytic lesions in lumbar spine accompanied breast cancer, in men it was prostate cancer. Geometry of FEM models were built based on CT scans of metastatic lumbar spine. We made the models for osteolytic metastases, osteosclerotic metastases, and metastases after surgery. Images were compared. We found a considerable concentration of strain, especially located in the posterior part of the vertebral body. In osteolytic lesions, the strain was located below the vertebral body with metastases. In osteosclerotic lesions, the strain was located in the anterior and posterior parts in and below the vertebral body with metastases. Surgery abolished the pathological strain. We conclude that metastases to the lumbar spine introduce a pathological strain on the lumbar body. The immobilization of the vertebral body around fractures abolished the strain.