Abe Shinya, Narra Nathaniel, Nikander Riku, Hyttinen Jari, Kouhia Reijo, Sievänen Harri
Department of Mechanical Engineering and Industrial Systems, Tampere University of Technology, Tampere, Finland.
Department of Electronics and Communications Engineering, BioMediTech, Tampere University of Technology, Tampere, Finland.
Bone. 2016 Nov;92:9-17. doi: 10.1016/j.bone.2016.07.021. Epub 2016 Jul 28.
Over 90% of hip fractures are caused by falls. Due to a fall-induced impact on the greater trochanter, the posterior part of the thin superolateral cortex of the femoral neck is known to experience the highest stress, making it a fracture-prone region. Cortical geometry of the proximal femur, in turn, reflects a mechanically appropriate form with respect to habitual exercise loading. In this finite element (FE) modeling study, we investigated whether specific exercise loading history is associated with femoral neck structural strength and estimated fall-induced stresses along the femoral neck. One hundred and eleven three-dimensional (3D) proximal femur FE models for a sideways falling situation were constructed from magnetic resonance (MR) images of 91 female athletes (aged 24.7±6.1years, >8years competitive career) and 20 non-competitive habitually active women (aged 23.7±3.8years) that served as a control group. The athletes were divided into five distinct groups based on the typical loading pattern of their sports: high-impact (H-I: triple-jumpers and high-jumpers), odd-impact (O-I: soccer and squash players), high-magnitude (H-M: power-lifters), repetitive-impact (R-I: endurance runners), and repetitive non-impact (R-NI: swimmers). The von Mises stresses obtained from the FE models were used to estimate mean fall-induced stresses in eight anatomical octants of the cortical bone cross-sections at the proximal, middle, and distal sites along the femoral neck axis. Significantly (p<0.05) lower stresses compared to the control group were observed: the H-I group - in the superoposterior (10%) and posterior (19%) octants at the middle site, and in the superoposterior (13%) and posterior (22%) octants at the distal site; the O-I group - in the superior (16%), superoposterior (16%), and posterior (12%) octants at the middle site, and in the superoposterior (14%) octant at the distal site; the H-M group - in the superior (13%) and superoposterior (15%) octants at the middle site, and a trend (p=0.07, 9%) in the superoposterior octant at the distal site; the R-I group - in the superior (14%), superoposterior (23%) and posterior (22%) octants at the middle site, and in the superoposterior (19%) and posterior (20%) octants at the distal site. The R-NI group did not differ significantly from the control group. These results suggest that exercise loading history comprising various impacts in particular is associated with a stronger femoral neck in a falling situation and may have potential to reduce hip fragility.
超过90%的髋部骨折由跌倒所致。由于跌倒时对大转子产生的冲击力，已知股骨颈薄的上外侧皮质的后部承受的应力最高，使其成为易骨折区域。反过来，股骨近端的皮质几何形状反映了一种相对于习惯性运动负荷而言机械上合适的形态。在这项有限元（FE）建模研究中，我们调查了特定的运动负荷史是否与股骨颈结构强度相关，并估计了跌倒引起的沿股骨颈的应力。从91名女运动员（年龄24.7±6.1岁，竞技生涯>8年）和20名作为对照组的非竞技性习惯性活跃女性（年龄23.7±3.8岁）的磁共振（MR）图像构建了111个用于侧方跌倒情况的三维（3D）近端股骨FE模型。根据运动员的典型运动负荷模式，将她们分为五个不同的组：高冲击组（H-I：三级跳远运动员和跳高运动员）、奇特冲击组（O-I：足球和壁球运动员）、高负荷组（H-M：举重运动员）、重复冲击组（R-I：耐力跑运动员）和重复非冲击组（R-NI：游泳运动员）。从FE模型获得的冯·米塞斯应力用于估计沿股骨颈轴近端、中部和远端部位皮质骨横截面的八个解剖八分圆内的平均跌倒引起的应力。与对照组相比，观察到应力显著（p<0.05）降低的情况如下：H-I组——在中部的上后部（10%）和后部（19%）八分圆，以及在远端的上后部（13%）和后部（22%）八分圆；O-I组——在中部的上部（16%）、上后部（16%）和后部（12%）八分圆，以及在远端的上后部（14%）八分圆；H-M组——在中部的上部（13%）和上后部（15%）八分圆，以及在远端上后部八分圆有一个趋势（p=0.07，9%）；R-I组——在中部的上部（14%）、上后部（23%）和后部（22%）八分圆，以及在远端的上后部（19%）和后部（20%）八分圆。R-NI组与对照组无显著差异。这些结果表明，特别是包含各种冲击的运动负荷史与跌倒情况下更强壮的股骨颈相关，并且可能有降低髋部脆弱性的潜力。
