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Comparing the fracture limits of the proximal femur under impact and quasi-static conditions in simulation of a sideways fall.
Journal of the Mechanical Behavior of Biomedical Materials ( IF 3.3 ) Pub Date : 2019-12-13 , DOI: 10.1016/j.jmbbm.2019.103593
Fatemeh Jazinizadeh 1 , Hojjat Mohammadi 2 , Cheryl E Quenneville 3
Affiliation  

Sideways falls onto the hip are responsible for a great number of fractures in older adults. One of the possible ways to prevent these fractures is through early identification of people at greatest risk so that preventive measures can be properly implemented. Many numerical techniques that are designed to predict the femur fracture risk are validated through performing quasi-static (QS) mechanical tests on isolated cadaveric femurs, whereas the real hip fracture is a result of an impact (IM) incident. The goal of this study was to compare the fracture limits of the proximal femur under IM and QS conditions in the simulation of a sideways fall to identify any possible relationship between them.

Eight pairs of fresh frozen cadaveric femurs were divided into two groups of QS and IM (left and right randomized). All femurs were scanned with a Hologic DXA scanner and then cut and potted in a cylindrical tube. To measure the stiffness in two conditions of the single-leg stance (SLS) and sideways fall (SWF), non-destructive tests at a QS displacement rate were performed on the two groups. For the destructive tests, the QS group was tested in SWF configuration with the rate of 0.017 mm/s using a material testing machine, and the IM group was tested in the same configuration inside a pneumatic IM device with the projectile target displacement rate of 3 m/s.

One of the IM specimens was excluded due to multiple strikes. The result of this study showed that there were no significant differences in the SLS and SWF stiffnesses between the two groups (P = 0.15 and P = 0.64, respectively). The destructive test results indicated that there was a significant difference in the fracture loads of the two groups (P < 0.00001) with the impact ones being higher; however, they were moderately correlated (R2 = 0.45). Also, the comparison of the fracture location showed a qualitatively good agreement between the two groups.

Using the relationship developed herein, results from another study were extrapolated with errors of less than 12%, showing that meaningful predictions for the impact scenario can be made based on the quasi-static tests. The result of this study suggests that there is a potential to replace IM tests with QS displacement rate tests, and this will provide important information that can be used for future studies evaluating clinical factors related to fracture risk.



中文翻译:

在侧向跌落的模拟中比较撞击和准静态条件下股骨近端的骨折极限。

侧身跌落到臀部是老年人骨折的主要原因。预防这些骨折的一种可能方法是通过尽早识别风险最大的人,以便可以适当地采取预防措施。通过对孤立的尸体股骨执行准静态(QS)力学测试,可以验证用于预测股骨骨折风险的许多数值技术,而真正的髋部骨折是撞击(IM)事件的结果。这项研究的目的是在侧向跌落的模拟中比较IM和QS条件下股骨近端的骨折极限,以识别它们之间的任何可能关系。

将八对新鲜冷冻的尸体股骨分为QS和IM两组(左右随机)。用Hologic DXA扫描仪扫描所有股骨,然后切开并装在圆柱管中。为了测量单腿姿态(SLS)和侧身跌倒(SWF)两种情况下的刚度,对两组进行了QS位移率的无损检测。对于破坏性测试,QS组使用材料测试机以SWF构型以0.017 mm / s的速率进行测试,IM组在相同的构型下在气动IM装置内进行了测试,弹丸目标位移率为3小姐。

由于多次罢工,IM样品之一被排除在外。这项研究的结果表明,两组之间的SLS和SWF刚度没有显着差异(分别为P = 0.15和P = 0.64)。破坏性测试结果表明,两组的断裂载荷之间存在显着差异(P <0.00001),而冲击载荷则更高。但是,它们之间具有中等相关性(R 2  = 0.45)。同样,骨折位置的比较显示两组之间在质量上有很好的一致性。

使用此处建立的关系,另一项研究的结果推断出的误差小于12%,这表明可以基于准静态测试对影响情景做出有意义的预测。这项研究的结果表明,有可能用QS位移率测试代替IM测试,这将提供重要的信息,可用于将来评估与骨折风险相关的临床因素的研究。

更新日期:2019-12-13
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