Assessment of Bone Fragility in Patients With Multiple Myeloma Using QCT-Based Finite Element Modeling

Abstract

Multiple myeloma (MM) is a malignant plasma cell disease associated with severe bone destruction. Surgical intervention is often required to prevent vertebral body collapse and resulting neurological complications; however, its necessity is determined by measuring lesion size or number, without considering bone biomechanics. Finite element (FE) modeling, which simulates the physiological loading, may improve the prediction of fragility. To test this, we developed a quantitative computed tomography (QCT)-based FE model of the vertebra and applied it to a dataset of MM patients with and without prevalent fracture. FE models were generated from vertebral QCT scans of the T (T if T was fractured) of 104 MM patients, 45 with fracture and 59 without, using a low-dose scan protocol (1.5 mm slice thickness, 4.0 to 6.5 mSv effective dose). A calibration phantom enabled the conversion of the CT Hounsfield units to FE material properties. Compressive loading of the vertebral body was simulated and the stiffness, yield load, and work to yield determined. To compare the parameters between fracture and nonfracture groups, t tests were used, and standardized odds ratios (sOR, normalized to standard deviation) and 95% confidence intervals were calculated. FE parameters were compared to mineral and structural parameters using linear regression. Patients with fracture showed lower vertebral stiffness (-15.2%; p = 0.010; sOR = 1.73; 95% CI, 1.11 to 2.70), yield force (-21.5%; p = 0.002; sOR = 2.09; 95% CI, 1.27 to 3.43), and work to yield (-27.4%; p = 0.001; sOR = 2.28; 95% CI, 1.33 to 3.92) compared to nonfracture patients. All parameters correlated significantly with vBMD (stiffness: R = 0.57, yield force: R = 0.59, work to yield: R = 0.50, p < 0.001), BV/TV (stiffness: R = 0.56, yield force: R = 0.58, work to yield: R = 0.49, p < 0.001), and Tb.Sp (stiffness: R = 0.51, yield force: R = 0.53, work to yield: R = 0.45, p < 0.001). FE modeling identified MM patients with compromised mechanical integrity of the vertebra. Higher sOR values were obtained for the biomechanical compared to structural or mineral measures, suggesting that FE modeling improves fragility assessment in these patients. © 2016 American Society for Bone and Mineral Research.

On the human vertebra computational modeling: a literature review

“…In in vivo studies, the choice of BCs in a single vertebra is challenging because BCs must replicate physiological loading conditions, including the contribution of the facet joints, and the effect of soft tissues, such as ligaments, muscles and intervertebral disc. In most studies performed on the single vertebra in in vivo, axial compression is the loading mode that is currently most investigated [22,44,110,111,[116][117][118][119]. This condition is replicated by applying a force or displacements at the top of the vertebral body and fully constraining the inferior surface of the vertebra.…”

“…This condition is replicated by applying a force or displacements at the top of the vertebral body and fully constraining the inferior surface of the vertebra. In some cases, a layer of PMMA with a certain thickness is assumed on both the proximal and distal surfaces of the vertebra to simulate similar conditions than those adopted during experimental tests, as in [110,111,[116][117][118]. However, in daily activities the vertebra can be subjected to more complex loading modes such as bending and eccentric compression [108].…”

“…Recently, CT-based FE models have been used to investigate the mechanical competence of vertebrae of clinical patients affected by metastatic lesions [22,116]. Costa et al [22] analyzed 12 vertebrae affected by metastatic lytic lesions and 18 controls.…”

Multiple Myeloma as a Bone Disease? The Tissue Disruption-Induced Cell Stochasticity (TiDiS) Theory

“…First, LBLs occur through specific mechanisms which have been almost fully identified, using ancillary pathways such as Wnt, inhibins, IGF1, as the atavic/survival phenotype [6]. Second, generalized bone loss, pre-existing to MM, is probably due to disruption of the mesenchymal stromal to osteoblastic transition and responsible of the early endosteal niche disruption [17,18,30,31].…”

Οικονομική Διαχείριση Απεικονιστικών Εξετάσεων Ακτινολογικών Εργαστηρίων Δημοσίων Νοσοκομείων Με Τη Χρήση Ολοκληρωμένου Συστήματος Χαρτογράφησης GIS

“… Οζηενπελία: Οξίδεηαη σο ε απψιεηα ηεο νζηηθήο ππθλφηεηαο πνπ θπκαίλεηαη κεηαμχ -1 θαη -2,5 απνθιίζεηο απφ ηε κέζε ηηκή ελφο ελήιηθα ηνπ ίδηνπ θχινπ θαη ηεο ίδηα θπιήο (Υξηζηνδνχινπ, 2017). Τπνινγίδεηαη ζε 4 -6,5 mSv πεξίπνπ (Campbell et al, 2017). (Silva et al, 2015).…”