Hip load capacity and yield load in men and women of all ages

Abstract

Quantitative computed tomography (QCT) based finite element (FE) models can compute subject-specific proximal femoral strengths, or fracture loads, that are associated with hip fracture risk. These fracture loads are more strongly associated with measured fracture loads than DXA and QCT measures and are predictive of hip fracture independently of DXA bone mineral density (BMD). However, interpreting FE-computed fracture loads of younger subjects for the purpose of evaluating hip fracture risk in old age is challenging due to limited reference data. The goal of this study was to address this issue by providing reference data for male and female adult subjects of all ages. QCT-based FE models of the left proximal femur of 216 women and 181 men, age 27 to 90 years, from a cohort of Rochester, MN residents were used to compute proximal femoral load capacity in single-limb stance and posterolateral fall loading (Stance_LC and Fall_LC, respectively) [US Patent No. 9,245,069] and yield load under fall loading (Fall_yield). To relate these measures to information about hip fracture, the CT scanner and calibration phantom were cross-calibrated with those from our previous prospective study of hip fracture in older fracture and control subjects, the Age Gene/Environment Susceptibility (AGES) Reykjavik cohort. We then plotted Stance_LC, Fall_LC and Fall_yield versus age for the two cohorts on the same graphs. Thus, proximal femoral strengths in individuals above 70 years of age can be assessed through direct comparison with the FE data from the AGES cohort which were analyzed using identical methods. To evaluate younger individuals, reductions in Stance_LC, Fall_LC and Fall_yield from the time of evaluation to age 70 years can be cautiously estimated from the average yearly cross-sectional decreases found in this study (108 N, 19.4 N and 14.4 N, respectively, in men and 120 N, 19.4 N and 21.6 N, respectively, in women), and the projected fracture loads can be compared with data from the AGES cohort. Although we did not set specific thresholds for identifying individuals at risk of hip fracture, these data provide some guidance and may be used to help establish diagnostic Hip Load Capacity -p. 3 criteria in future. Additionally, given that these data were nearly entirely from Caucasian subjects, future research involving subjects of other races/ethnicities is necessary.

Soft tissue radiodensity parameters mediate the relationship between self-reported physical activity and lower extremity function in AGES-Reykjavík participants

“…There were also a limited number of covariates considered for this work; in addition to age, sex, BMI, and LEF AGES-I it may have been of interest to test other comorbidities, biometrics, or psychosocial factors in our models 45 . Likewise, as the AGES-Reykjavík study was almost entirely comprised of Caucasian subjects 46 , these findings may not be generalizable to other races or ethnicities.…”

Post-operative fracture risk assessment following tumor curettage in the distal femur: a hybrid in vitro and in silico biomechanical approach

“…However, the Drucker–Prager yield criterion 55 , which is an approximation to the Mohr–Coulomb law and a modification of the Von Mises yield criterion, is applied in some studies modelling bone as a brittle material with isotropic material properties 52 , 53 . The distortion energy failure theory applied in our study has also been widely used since its validation as a robust theory for bone failure when using elastic–plastic and isotropic material properties for bone 16 , 33 , 43 , 54 . Warden et al 43 calculated femoral strength considering heterogeneous and non-linear post-yield material properties under a compressive load that was applied by an incremental displacement on the femoral head.…”

“…They computed the element stress and strain, using individual element’s stress–strain relationship, similar to the relations used in this study, in conjunction with the von Mises yield criterion 43 . Most recently, a study measured hip load capacity using elastic–plastic and isotropic modeling of bone in conjunction with the distortion energy yield criterion 54 .…”

In Vivo Assessment of Age‐ and Loading Configuration‐Related Changes in Multiscale Mechanical Behavior of the Human Proximal Femur Using MRI‐Based Finite Element Analysis

“…However, over‐adapted femora are particularly fragile under sideways falls, 33 especially in the elderly. A recent experiment has shown that the stance load capacity of the femur is greater than sideways fall load capacity 21 . The trabecular bone undergoes changes in bone characteristics earlier than cortical bone during the onset of osteoporosis 34 .…”

“…Loading and boundary conditions were applied to each FE model of the proximal femur to simulate the sideways fall and stance configurations, similar to previous studies 16‐19 . To evaluate the intrinsic mechanical behavior of the proximal femur, each FE model was placed under a standard “virtual testing” configuration (either stance or sideways fall) and loaded with the same force 8,16,20,21 . For the sideways fall configuration, a load of 300N was vertically applied to the femoral head when the femoral shaft was tilted at 10° with respect to the ground and the femoral neck was internally rotated by 15°; the distal end of the femur was fully restrained (Fig.…”