van den Kroonenberg A J, Hayes W C, McMahon T A
Orthopedic Biomechanics Laboratory, Department of Orthopedic Surgery, Charles A. Dana Research Institute, Harvard Thorndike Laboratory, Beth Israel Hospital, Cambridge, MA, USA.
J Biomech. 1996 Jun;29(6):807-11. doi: 10.1016/0021-9290(95)00134-4.
Fall dynamics have largely been ignored in the study of hip fracture etiology and in the development of hip fracture prevention strategies. In this study, we asked the following questions: (1) What are the ranges of hip impact velocities associated with a sideways fall from standing height? (2) What are the ranges of body configurations at impact? and (3) How do protective reflexes such as muscle activation or using an outstretched hand influence fall kinematics? To answer these questions, we recruited six young healthy athletes who performed voluntary sideways falls on a thick foam mattress. Several categories of falls were investigated: (a) muscle-active vs muscle-relaxed falls; (b) falls from a standing position or from walking; and (c) falls in which an outstretched arm was used to break the fall. Each fall was videotaped at 60 frames s(-1). Fall kinematics parameters were obtained by digitizing markers placed on anatomical points of interest. The mean value for vertical hip impact velocity was 2.75 ms(-1) (+ or - 0.42 ms(-1) [S.D.]). The mean value for trunk angle (the angle between the trunk and the vertical) was 17.3 degrees (+ or - 11.5 degrees [S.D.]). We found a 38 percent reduction in the trunk angle at impact, and a 7 percent reduction in hip impact velocity for relaxed vs muscle-active falls. Finally, regarding the. falls in which an outstretched arm was used, only two out of the six subjects were able to break the fall with their arm or hand. For the remaining subjects hip impact occurred first, followed by contact of the arm or hand.
在髋部骨折病因学研究以及髋部骨折预防策略的制定过程中，跌倒动力学在很大程度上被忽视了。在本研究中，我们提出了以下问题：（1）从站立高度侧向跌倒时，髋部撞击速度的范围是多少？（2）撞击时身体姿势的范围是多少？以及（3）诸如肌肉激活或使用伸出的手等保护性反射如何影响跌倒运动学？为了回答这些问题，我们招募了六名年轻健康的运动员，他们在厚泡沫床垫上进行自愿侧向跌倒。研究了几类跌倒情况：（a）肌肉主动型跌倒与肌肉放松型跌倒；（b）从站立姿势或行走时跌倒；以及（c）使用伸出的手臂来缓冲跌倒的情况。每次跌倒都以每秒60帧的速度拍摄。通过对放置在感兴趣解剖点上的标记进行数字化处理来获取跌倒运动学参数。垂直髋部撞击速度的平均值为2.75米/秒（±0.42米/秒[标准差]）。躯干角度（躯干与垂直方向之间的角度）的平均值为17.3度（±11.5度[标准差]）。我们发现，与肌肉主动型跌倒相比，肌肉放松型跌倒时撞击时的躯干角度减少了38%，髋部撞击速度降低了%。最后，对于使用伸出手臂的跌倒情况，六名受试者中只有两名能够用手臂或手缓冲跌倒。对于其余受试者，首先发生髋部撞击，随后是手臂或手接触。 （原文此处“a 7 percent reduction in hip impact velocity for relaxed vs muscle-active falls”中“7 percent reduction”前似乎少了具体内容，译文按原文翻译）
