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Biomechanics

Fracture Risk Prediction

The skeleton is the third most common site of metastatic cancer, and nearly half of all cancers metastasize to bone. As a result of new and aggressive treatments, cancer patients are living longer, but at sites of skeletal metastasis, fractures occur in up to 35 percent of affected bones after minimal trauma.

Preventing fractures due to skeletal metastases depends on objective criteria that reflect the interaction of the tumor with the host bone. While much has been learned about the mechanisms of skeletal metastasis, clinicians continue to make subjective assessments regarding a patient's fracture risk and response to treatment based on plain radiographs and clinical symptoms now recognized to be inaccurate. Metastatic cancer alters both the material and geometric properties of the bone; failure to account for changes in both of these parameters limits the accuracy of these fracture predictions.

Fracture Risk Prediction (click to enlarge)

Rigidity is the structural property that integrates both the material and geometric properties of the bone; the axial (EA), bending (EI), and torsional (GJ) rigidity determine the capacity of the bone to resist axial, bending and twisting loads respectively. We propose that the structural rigidity of a bone afflicted with metastatic cancer provides a mechanical assay that represents the changes in bone tissue material and bone geometric properties induced by the cancer. Since it is the weakest segment through the bone that dictates the load capacity of the entire bone, we have developed algorithms to calculate the minimal rigidity of a bone containing an osteolytic lesion using serial, trans-axial, computed tomography (CT) images through the affected bone to measure both the bone tissue mineral density and cross-sectional geometry.

The accuracy of this approach has been validated ex-vivo and in-vivo. Therefore, we hypothesize that CT-based rigidity analysis (CTRA) predicts the fracture risk of bones containing osteolytic metastases more accurately than current clinical and/or radiographic guidelines based on symptoms, anatomic location of the affected bone and the size and location of the lesion within the affected bone.

» Learn more about our ongoing multi-center study, initially funded by the Musculoskeletal Tumor Society (MSTS).

Relevant Publications

Human Studies: 21, 22, 27, 32, 34, 37, 40
Animal Studies: 25, 26, 31, 35


Bone Biomechanics


Contact Information

Nazarian Lab
Center for Advanced Orthopaedic Studies
Beth Israel Deaconess Medical Center
330 Brookline Ave., RN 115
Boston, MA 02215
617-667-8512
anazaria@bidmc.harvard.edu

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