FALL BIOMECHANICS AND HIP FRACTURE RISK

描述(改编自申请人的摘要)：跌倒和跌倒相关 伤害是最严重、最常见、最昂贵的医疗问题之一。 面对老年人。全国每年约有30万例髋部骨折 美国，其中90%以上与跌倒有关。注意到之前没有一项研究 研究了跌倒力学在髋部骨折病因中的作用， 在上一个资助期内， 就在臀部撞击被确定之前。这些信息被用来 估计冲击力，并开发分析模型来解释和 将这些实验结果推广到虚弱的老年人。申请人 在这些研究中，表明撞击速度对物体最敏感 身高和冲击力对体重的影响，即主动和被动能量 跌倒过程中肢体关节和肌肉的吸收 吸收大约71%的可用势能，这归因于 侧面是危险的，部分原因是臀部首先接触地面，甚至 在年轻志愿者的指导下，打破自我引发的“跌倒” 伸出的手。申请人还表明，冲击力可以 随着躯干肌肉的激活而加倍，增加了3倍 粗隆软组织厚度减少了约三分之一的冲击力， 平均跌落的撞击力超过了 老年髋关节减少约35%。最近，申请人和其他人进一步 从倾斜的监视研究中显示出来，特别是那些 这会对髋部造成冲击，使髋部骨折的风险从6岁增加到 30倍，而与之相关的风险增加约3倍 髋部骨矿密度的标准差降低。然而， 尽管摔倒在病因学上显然很重要， 以前对姿势稳定性的研究主要集中在运动方面。 前进的平面。此外，尽管之前的研究有所帮助， 找出那些使老年人跌倒的高风险因素，不是 以前的工作已经确定了更有可能跌倒的受试者 或检查不对称性对下肢力量的影响， 反应时间或肌肉骨骼病理是高血压的潜在危险因素 从侧面坠落。鉴于髋部骨折的风险显著增加， 摔倒在一边，目标1是要了解 掉到一边。因为预防跌倒的努力到现在还没有 显示伤害性跌倒发生率和跌倒风险的降低 评估不能用来确定一小部分失败者 将遭受髋部骨折，目标2是识别高龄的老年受试者 横盘下跌的风险。最后，由于髋部骨折是可以预防的 通过降低确实发生的跌倒的严重性，目标3建议 探索两种新的干预战略，一种侧重于减少影响 一个是速度，另一个是冲击力。

DESCRIPTION (Adapted from the applicant's Abstract): Falls and fall related injuries are among the most serious, common and costly medical problems facing the elderly. There are about 300,000 hip fractures annually in the U.S., over 90% of them associated with falls. Noting that no previous study had examined the role of fall mechanics in the etiology of hip fracture, during the previous funding period, the configurations and velocities of fallers just before hip impact was determined. That information was used to estimate impact force, and to develop analytical models for interpreting and extending these experimental results to the frail elderly. The applicant showed, in these studies, that impact velocity is most sensitive to body height and impact force to body weight, that active and passive energy absorption in the joints and muscles of the lower extremity during falling absorb roughly 71% of the potential energy available and that falls to the side are dangerous in part because the hip contacts the ground first, even in young volunteers instructed to break a self-initiated "fall" with the outstretched hand. The applicant has also shown that impact forces can double with activation of the trunk muscles, that a 3-fold increase in trochanteric soft tissue thickness reduces impact force by about one-third, and that impact forces for an average fall exceed the strength of the elderly hip by about 35%. Recently, the applicant, and others, have further shown from surveillance studies that falls to the side, particularly those that end with impact on the hip, raise the risk of hip fracture from 6- to 30-fold, compared to about 3-fold increases in risk associated with one standard deviation reduction in bone mineral density at the hip. And yet, despite the apparently crucial etiologic importance of falling to the side, previous research on postural stability has largely focused on motion in the plane of progression. In addition, while previous studies have helped identify those factors that place the elderly at high risk for falling, no previous work has identified subjects at increased risk of falling to the side or examined the effects of asymmetries in lower extremity strength, reaction time, or musculoskeletal pathology as potential risk factors for sideways falls. Given the dramatically increased risk of hip fracture from a fall to the side, Aim 1 is to understand the fundamental dynamics of falling to the side. Since fall prevention efforts have not as yet demonstrated reductions in the incidence of injurious falls and fall risk assessments cannot be used to identify the small fraction of fallers who will suffer a hip fracture, Aim 2 is to identify elderly subjects at high risk for sideways falls. And finally, since hip fracture can be prevented by reducing the severity of those falls that do occur, Aim 3 proposes to explore two new intervention strategies, one focused on reducing impact velocity and the other on impact force.