Ct-based finite element models can be used to estimate experimentally measured failure loads in the proximal femur

• Published in: Bone (New York, N.Y.) Vol. 50; no. 4; pp. 824 - 829
• Main Authors: Koivumäki, Janne E.M, Thevenot, Jérôme, Pulkkinen, Pasi, Kuhn, Volker, Link, Thomas M, Eckstein, Felix, Jämsä, Timo
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 01.04.2012
• Subjects: Aged; Aged, 80 and over; Biological and medical sciences; Biomechanics. Biorheology; Cadaver; Female; Femoral Fractures - diagnostic imaging; Femoral Fractures - physiopathology; Femur - diagnostic imaging; Femur - physiopathology; Finite Element Analysis; Fundamental and applied biological sciences. Psychology; Humans; Injuries of the limb. Injuries of the spine; Male; Medical sciences; Middle Aged; Models, Anatomic; Orthopedics; Reproducibility of Results; Stress, Mechanical; Time Factors; Tissues, organs and organisms biophysics; Tomography, X-Ray Computed; Traumas. Diseases due to physical agents; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Weight-Bearing; Hip fracture; Femur; Bone biomechanics; Bone strength; Finite element; Proximal; Load; Radiodiagnosis; Diseases of the osteoarticular system; Fracture; Trauma; Hip; Biomechanics; Morphology; Medical imagery; Models; Computerized axial tomography; Bone; Failure; Strength
• ISSN: 8756-3282; 1873-2763
• DOI: 10.1016/j.bone.2012.01.012

Abstract The objective of this experimental finite element (FE) study was to assess the accuracy of a simulation model estimate of the experimentally measured fracture load of the proximal femur in a sideways fall. Sixty-one formalin-fixed cadaver femora (41 female and 20 male) aged 55–100 years (an average of 80 years) were scanned with a multi-detector CT scanner and were mechanically tested for failure in a sideways fall loading configuration. Twenty-one of these femurs were used for training purposes, and 40 femurs were used for validation purposes. The training set FE models were used to establish the strain threshold for the element failure criteria. Bi-linear elastoplastic FE analysis was performed based on the CT images. The validation set was used to estimate the fracture loads. The Drucker-Prager criterion was applied to determine the yielding and the maximum principal stress criteria and the minimum principal strain criteria for element failure in tension and in compression, respectively. The estimated fracture load values were highly correlated with the experimental data (r = 0.931; p < 0.001). The slope was 0.929, with an intercept of 258 N, which was not significantly different from 1 and 0, respectively. The study shows that it is possible to estimate the fracture load with relatively high accuracy in a sideways fall configuration by using the CT-based FE method. This method may therefore be applied for studying the biomechanical mechanisms of hip fractures.