A Subject-Specific Dynamics Model for Predicting Impact Force in Elderly Lateral Fall

Luo, Yunhua; Sarvi, Masoud Nasiri; Sun, Pei Dong; Ouyang, Jun

doi:10.4028/www.scientific.net/amm.446-447.339

Cited by 4 publications

(6 citation statements)

References 13 publications

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“…The improved features of the dynamics model compared to what was presented in our previous study (Luo et al, 2014b;Nasiri Sarvi et al, 2014) include:…”

Section: Prediction Of the Fall-induced Loading Condition By A Subjecmentioning

confidence: 90%

“…A three-link dynamics model, developed by the authors and validated by experiments (Luo et al, 2014b;Nasiri Sarvi et al, 2014), was improved in this study to accurately predict the fallinduced loading condition on the femur. The improved features of the dynamics model compared to what was presented in our previous study (Luo et al, 2014b;Nasiri Sarvi et al, 2014) include:…”

Section: Prediction Of the Fall-induced Loading Condition By A Subjecmentioning

confidence: 99%

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A two-level subject-specific biomechanical model for improving prediction of hip fracture risk

Sarvi

Luo

2015

Clinical Biomechanics

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“…The improved features of the dynamics model compared to what was presented in our previous study (Luo et al, 2014b;Nasiri Sarvi et al, 2014) include:…”

Section: Prediction Of the Fall-induced Loading Condition By A Subjecmentioning

confidence: 90%

Section: Prediction Of the Fall-induced Loading Condition By A Subjecmentioning

confidence: 99%

A two-level subject-specific biomechanical model for improving prediction of hip fracture risk

Sarvi

Luo

2015

Clinical Biomechanics

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“…1 Load-strength ratio, major and sublevel biomechanical variables before touching the ground may change the magnitude of impact force [8,112,116]. A more accurate way is to determine the impact force by fall simulation using a dynamics model constructed from the subject's whole body medical image [8,111,113,114]. It should be realized that assumptions, for example, the fall type and direction, have been introduced in both fall tests and dynamics simulations, which may be very different from those in a real-world fall.…”

Section: Biomechanical Variables Determining Hip Fracture Riskmentioning

confidence: 99%

“…Therefore, in clinical studies, the information of fall and impact force is not available or incomplete in most cases. In biomechanical studies, sideways fall is considered as the most critical situation to develop hip fracture and the impact force is predicted by fall dynamics simulation [8,111,113]. Due to the simplifications introduced in the dynamics models, the predicted impact force may not be the actual one occurring in the fracture cases recorded in clinic.…”

Section: Biomechanical Variablesmentioning

confidence: 99%

“…For assessment purpose, the impact force can be estimated from fall test [14, 17, [106][107][108][109][110] or determined by fall dynamics simulation [8,[111][112][113][114]. Empirical formulas established from experimental data have been proposed to estimate the impact force using the subject's body weight and height [107,110,115].…”

Section: Biomechanical Variables Determining Hip Fracture Riskmentioning

confidence: 99%

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A biomechanical sorting of clinical risk factors affecting osteoporotic hip fracture

Luo

2015

Osteoporos Int

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Osteoporotic fracture has been found associated with many clinical risk factors, and the associations have been explored dominantly by evidence-based and case-control approaches. The major challenges emerging from the studies are the large number of the risk factors, the difficulty in quantification, the incomplete list, and the interdependence of the risk factors. A biomechanical sorting of the risk factors may shed lights on resolving the above issues. Based on the definition of load-strength ratio (LSR), we first identified the four biomechanical variables determining fracture risk, i.e., the risk of fall, impact force, bone quality, and bone geometry. Then, we explored the links between the FRAX clinical risk factors and the biomechanical variables by looking for evidences in the literature. To accurately assess fracture risk, none of the four biomechanical variables can be ignored and their values must be subject-specific. A clinical risk factor contributes to osteoporotic fracture by affecting one or more of the biomechanical variables. A biomechanical variable represents the integral effect from all the clinical risk factors linked to the variable. The clinical risk factors in FRAX mostly stand for bone quality. The other three biomechanical variables are not adequately represented by the clinical risk factors. From the biomechanical viewpoint, most clinical risk factors are interdependent to each other as they affect the same biomechanical variable(s). As biomechanical variables must be expressed in numbers before their use in calculating LSR, the numerical value of a biomechanical variable can be used as a gauge of the linked clinical risk factors to measure their integral effect on fracture risk, which may be more efficient than to study each individual risk factor.

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On the internal reaction forces, energy absorption, and fracture in the hip during simulated sideways fall impact

et al. 2018

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The majority of hip fractures have been reported to occur as a result of a fall with impact to the greater trochanter of the femur. Recently, we developed a novel cadaveric pendulum-based hip impact model and tested two cadaveric femur-pelvis constructs, embedded in a soft tissue surrogate. The outcome was a femoral neck fracture in a male specimen while a female specimen had no fracture. The aim of the present study was, first, to develop a methodology for constructing and assessing the accuracy of explicit Finite Element Models (FEMs) for simulation of sideways falls to the hip based on the experimental model. Second, to use the FEMs for quantifying the internal reaction forces and energy absorption in the hip during impact. Third, to assess the potential of the FEMs in terms of separating a femoral fracture endpoint from a non-fracture endpoint. Using a non-linear, strain rate dependent, and heterogeneous material mapping strategy for bone tissue in these models, we found the FEM-derived results to closely match the experimental test results in terms of impact forces and displacements of pelvic video markers up to the time of peak impact force with errors below 10%. We found the internal reaction forces in the femoral neck on the impact side to be approximately 35% lower than the impact force measured between soft tissue and ground for both specimens. In addition, we found the soft tissue to be the component that absorbed the largest part of the energy of the tissue types in the hip region. Finally, we found surface strain patterns derived from FEM results to match the fracture location and extent based on post testing x-rays of the specimens. This is the first study with quantitative data on the energy absorption in the pelvic region during a sideways fall.

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A Subject-Specific Dynamics Model for Predicting Impact Force in Elderly Lateral Fall

Cited by 4 publications

References 13 publications

A two-level subject-specific biomechanical model for improving prediction of hip fracture risk

A two-level subject-specific biomechanical model for improving prediction of hip fracture risk

A biomechanical sorting of clinical risk factors affecting osteoporotic hip fracture

On the internal reaction forces, energy absorption, and fracture in the hip during simulated sideways fall impact

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