ASSESSMENT OF VERTEBRAL STRENGTH IN MULTIPLE MYELOMA PATIENTS: A FINITEELEMENT STUDY
Anitha D.1, Subburaj K.1, Kirschke J. S.2, Baum T.2
1Singapore University of Technology & Design, Singapore;
2Technische Universitaet Muenchen
Multiple myeloma (MM) is a skeletal malignant disease, with a less than 50% 5-year survival rate. Although the current indications for MM is the bone mineral density (BMD), a threshold for an accurate diagnosis of MM has not been previously established. Radiographic scan procedures such as computed tomography (CT) are common in diagnosing MM through the detection of osteolytic lesions or significant diffuse bone losses, but herein lies high susceptibility to vertebral compression fractures (VCFs). Hence, this study assessed differences in FE-predicted fracture load between MM patients with and without VCFs in the thoracic and lumbar segments of the spine. Multidetector CT (MDCT) images of two MM subjects (1 with VCFs and 1 without VCFs) were used to generate three-dimensional (3D) models of the whole spine. For each subject, the thoracic segments, 1 to 12 (T1-T12) and lumbar segments, 1 to 5 (L1-L5) were segmented and meshed. Heterogeneous, non-linear anisotropic material properties were applied by discretizing each vertebral segment into 10 distinct sets of materials. A compressive load was simulated by constraining the surface nodes on the inferior endplate in all directions, and a displacement load was applied on the surface nods on the superior endplate. The MM subject with VCFs had originally attained fractures in the T4, T5, T12, L1 and L5 segments whereas the MM subject without VCFs attained none. The former displayed large and abrupt differences in fracture loads between adjacent vertebrae segments, unlike the latter, which exhibited progressive differences instead. This was also further quantified by calculated relative changes in fracture load values. The abrupt changes that indicate instability enables ease of identification of segments at high fracture risk. Clinicians will be able to work with a pre-emptive treatment strategy as they can focus on a more targeted therapy at the affected vertebrae segments.