Prediction of Hip Failure Load: In Vitro Study of 80 Femurs Using Three Imaging Methods and Finite Element Models—The European Fracture Study (EFFECT)

Abstract

Purpose To evaluate the performance of three imaging methods (radiography, dual-energy x-ray absorptiometry [DXA], and quantitative computed tomography [CT]) and that of a numerical analysis with finite element modeling (FEM) in the prediction of failure load of the proximal femur and to identify the best densitometric or geometric predictors of hip failure load. Materials and Methods Institutional review board approval was obtained. A total of 40 pairs of excised cadaver femurs (mean patient age at time of death, 82 years ± 12 [standard deviation]) were examined with (a) radiography to measure geometric parameters (lengths, angles, and cortical thicknesses), (b) DXA (reference standard) to determine areal bone mineral densities (BMDs), and (c) quantitative CT with dedicated three-dimensional analysis software to determine volumetric BMDs and geometric parameters (neck axis length, cortical thicknesses, volumes, and moments of inertia), and (d) quantitative CT-based FEM to calculate a numerical value of failure load. The 80 femurs were fractured via mechanical testing, with random assignment of one femur from each pair to the single-limb stance configuration (hereafter, stance configuration) and assignment of the paired femur to the sideways fall configuration (hereafter, side configuration). Descriptive statistics, univariate correlations, and stepwise regression models were obtained for each imaging method and for FEM to enable us to predict failure load in both configurations. Results Statistics reported are for stance and side configurations, respectively. For radiography, the strongest correlation with mechanical failure load was obtained by using a geometric parameter combined with a cortical thickness (r(2) = 0.66, P < .001; r(2) = 0.65, P < .001). For DXA, the strongest correlation with mechanical failure load was obtained by using total BMD (r(2) = 0.73, P < .001) and trochanteric BMD (r(2) = 0.80, P < .001). For quantitative CT, in both configurations, the best model combined volumetric BMD and a moment of inertia (r(2) = 0.78, P < .001; r(2) = 0.85, P < .001). FEM explained 87% (P < .001) and 83% (P < .001) of bone strength, respectively. By combining (a) radiography and DXA and (b) quantitative CT and DXA, correlations with mechanical failure load increased to 0.82 (P < .001) and 0.84 (P < .001), respectively, for radiography and DXA and to 0.80 (P < .001) and 0.86 (P < .001) , respectively, for quantitative CT and DXA. Conclusion Quantitative CT-based FEM was the best method with which to predict the experimental failure load; however, combining quantitative CT and DXA yielded a performance as good as that attained with FEM. The quantitative CT DXA combination may be easier to use in fracture prediction, provided standardized software is developed. These findings also highlight the major influence on femoral failure load, particularly in the trochanteric region, of a densitometric parameter combined with a geometric parameter. (©) RSNA, 2016 Online supplemental material is available for this article.

Physical Activity for Strengthening Fracture Prone Regions of the Proximal Femur

“…The sensitivity of fracture force to force direction is a reflection of proximal femur anatomy, with cadaveric studies demonstrating that the proximal femur can withstand forces two-to-four times greater in the single-limb stance direction than forces in a posterolateral fall direction [39, 40]. During a sideways fall onto the greater trochanter, the stress pattern within the femoral neck is reversed from that experienced during weight-bearing.…”

Cost-effectiveness of Virtual Bone Strength Testing in Osteoporosis Screening Programs for Postmenopausal Women in the United States

“…Of note, textural analysis of the femur on pelvic radiographs is another option for assessment of fracture risk and is better for prediction of fragility fracture compared with DXA (56). In a recent cadaver study (57), investigators compared finite element–based quantitative CT (as used in our model) with DXA, radiography, and CT-based bone measurement for femur fracture prediction. That study showed that quantitative CT was the best method for prediction of failure load (57).…”

“…In a recent cadaver study (57), investigators compared finite element–based quantitative CT (as used in our model) with DXA, radiography, and CT-based bone measurement for femur fracture prediction. That study showed that quantitative CT was the best method for prediction of failure load (57). …”

The influence of anisotropic voxel caused by field of view setting on the accuracy of three-dimensional reconstruction of bone geometric models

“…4,[11][12][13][14] In addition to DXA and QCT, more researchers tend to use the finite element analysis (FEA) method to investigate bone features, 4,[15][16][17][18] since FEA reveals information of the three-dimensional (3D) morphology, the material property and the loading distribution of bone, which may provide a more accurate bone strength prediction. 4,16,17,[19][20][21][22][23] Among all factors that affect FEA analysis results, a critical one is bone geometric model. 22 Digital Imaging and Communications in Medicine (DICOM) is the international standard of medical imaging.…”