A pilot finite element study of an osteoporotic L1-vertebra compared to one with normal T-score.
In this paper, two patient-specific finite element (FE) models of both an L1 vertebra with a normal T-score and a mildly wedging, osteoporotic one were created and analysed under usual action. Utilising commercial software packages for image processing and FE analysis (FEA) along with in house computer codes for a posteriori assignment of material properties, in vivo high-resolution spiral computed tomography of the entire vertebrae and FEA were combined. Using the vertebra with a normal T-score as baseline it was found that the maximum value of the von Mises stress in the osteoporotic vertebra was 60% higher but still far below bone strength, while the maximum value of von Mises strain in the same vertebra was 148% higher than that of the vertebra with normal T-score. In the vertebra with normal T-score, 17% of its volume exhibited values of von Mises strain higher than the threshold of 4500 μstrains, referenced by Homminga et al. as a threshold of fracture risk, while in the osteoporotic one this percentage was raised up to 37%. The results suggested that the osteoporotic vertebra is susceptible to fracture due to raised strains and not stresses.
Provatidis
C
C
Department of Mechanical Engineering, National Technical University of Athens, Zografos Campus, Athens, Greece. cprovat@central.ntua.gr
Vossou
C
C
Koukoulis
I
I
Balanika
A
A
Baltas
C
C
Lyritis
G
G
D000368:Aged; D001696:Biomechanical Phenomena; D001698:Biomedical Engineering; D015519:Bone Density; D003198:Computer Simulation; D055119:Elastic Modulus; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D008954:Models, Biological; D015663:Osteoporosis, Postmenopausal / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D058866:Osteoporotic Fractures / Q000209:etiology; D010865:Pilot Projects; D012016:Reference Values; D012307:Risk Factors; D014057:Tomography, X-Ray Computed; D016474:Weight-Bearing / Q000502:physiology