Robinovitch S N, Hayes W C, McMahon T A
Department of Orthopedic Surgery, Charles A. Dana Research Institute, Beth Israel Hospital, Boston, MA, USA.
J Biomech Eng. 1995 Nov;117(4):409-13. doi: 10.1115/1.2794200.
Recent studies suggest that hip padding systems reduce the incidence of hip fractures during falls. However, no data exist on the force attenuating capacity of hip pads under realistic fall impact conditions, and thus it is difficult to compare the protective merit of various pad designs. Our goal is to design a comfortable hip padding system which reduces femoral impact force in a fall below the mean force required to fracture the elderly cadaveric femur. In pursuit of this objective, we designed and constructed a hip pad testing system consisting of an impact pendulum and surrogate human pelvis. We then developed a hip pad containing a shear-thickening material which allows for shunting of the impact energy away from the femur and into the surrounding soft tissue. Finally, we conducted experiments to assess whether the surrogate pelvis accurately represents the impact behavior of the human female pelvis in a fall, and to determine whether our energy-shunting pad attenuates femoral impact force in a fall more effectively than seven available padding systems. We found the surrogate pelvis accurately represented the human female pelvis in regional variation in soft tissue stiffness, total effective stiffness and damping, and impact force attenuation provided by trochanteric soft tissues. We also found that our padding system attenuated femoral impact force by 65 percent, thereby providing two times the force attenuation of the next best system. Moreover, the energy-shunting pad was the only system capable of lowering femoral impact force well below the mean force required to fracture the elderly femur in a fall loading configuration. These results suggest that the force attenuating potential of hip pads which focus on shunting energy away from the femur is superior to those which rely on absorbing energy in the pad material. While these in-vitro results are encouraging, carefully designed prospective clinical trials will be necessary to determine the efficacy of these approaches to hip fracture prevention.
最近的研究表明，髋部缓冲系统可降低跌倒时髋部骨折的发生率。然而，在实际跌倒冲击条件下，尚无关于髋部护垫力衰减能力的数据，因此难以比较各种护垫设计的防护效果。我们的目标是设计一种舒适的髋部缓冲系统，在跌倒时将股骨冲击力降低至低于老年尸体股骨骨折所需的平均力。为了实现这一目标，我们设计并构建了一个髋部护垫测试系统，该系统由一个冲击摆和模拟人体骨盆组成。然后，我们开发了一种含有剪切增稠材料的髋部护垫，这种材料能够将冲击能量从股骨分流到周围的软组织中。最后，我们进行了实验，以评估模拟骨盆是否能准确代表人类女性骨盆在跌倒时的冲击行为，并确定我们的能量分流护垫在跌倒时是否比七种现有的缓冲系统更有效地衰减股骨冲击力。我们发现，模拟骨盆在软组织刚度、总有效刚度和阻尼的区域变化以及转子软组织提供的冲击力衰减方面准确地代表了人类女性骨盆。我们还发现，我们的缓冲系统将股骨冲击力衰减了65%，从而提供了比次优系统两倍的力衰减。此外，能量分流护垫是唯一能够将股骨冲击力降低到远低于跌倒加载配置下老年股骨骨折所需平均力的系统。这些结果表明，专注于将能量从股骨分流的髋部护垫的力衰减潜力优于那些依赖于在护垫材料中吸收能量的护垫。虽然这些体外结果令人鼓舞，但仍需要精心设计的前瞻性临床试验来确定这些预防髋部骨折方法的疗效。
