Hayes W C, Myers E R, Robinovitch S N, Van Den Kroonenberg A, Courtney A C, McMahon T A
Department of Orthopedic Surgery, Charles A. Dana Research Institute, Harvard Medical School, Boston, MA USA. wch/bihobl2.bih.harvard.edu
Bone. 1996 Jan;18(1 Suppl):77S-86S. doi: 10.1016/8756-3282(95)00383-5.
Falls and fall-related injuries are among the most serious and common medical problems experienced by the elderly. Hip fracture, one of the most severe consequences of falling in the elderly, occurs in only about 1% of falls. Despite this, hip fracture accounts for a large share of the disability, death, and medical costs associated with falls. As measured by their frequency, influence on quality of life, and economic cost, hip fractures are a public health problem of crisis proportions. Without successful international initiatives aimed at reducing the incidence of falls and hip fractures, the implications for allocations of health resources in this and the next century are staggering. Identifying those at risk for harmful falls requires an understanding of what kinds of falls result in injury and fracture. In elderly persons who fall, in most of whom hip bone mineral density is already several standard deviations below peak values, fall severity (as reflected in falling to the side and impacting the hip) and body habitus are important risk factors for hip fracture and touch on a domain of risk entirely missed by knowledge of bone mineral density. These findings clearly suggest that factors related to both loading and bone fragility play important roles in the etiology of hip fracture. We provide a strategy, based on engineering approaches to fracture risk prediction, for determining the relative etiologic importance of loading and bone fragility and to summarize some of what is known about both sets of factors. We define a factor of risk, phi, as the ratio of the loads applied to the hip divided by the loads necessary to cause fracture and summarize available data on the numerator and the denominator of phi. We then provide an overview of the complex interplay between the risks associated with the initiation, descent, and impact phases of a fall, thereby suggesting an organized approach for evaluating intervention efforts being used to prevent hip fractures. The findings emphasize the continuing need for combined intervention strategies that focus on fall prevention, reductions in fall severity, and maintaining or increasing femoral bone mass and strength, either through targeted exercise programs, optimal nutrition (Ca, Vitamin D), and/or in the use of osteodynamic agents. By developing and refining the factor of risk, a property that captures both the contributions of bone density and the confounding influences of body habitus and fall severity, we believe these intervention strategies can be targeted more appropriately.
跌倒及与跌倒相关的损伤是老年人面临的最严重且最常见的医学问题之一。髋部骨折是老年人跌倒最严重的后果之一，仅约1%的跌倒会导致髋部骨折。尽管如此，髋部骨折在与跌倒相关的残疾、死亡及医疗费用中占了很大比例。从发生频率、对生活质量的影响以及经济成本衡量，髋部骨折是一个具有危机规模的公共卫生问题。若没有旨在降低跌倒和髋部骨折发生率的成功国际举措，在本世纪及下个世纪对卫生资源分配的影响将是惊人的。识别有发生有害跌倒风险的人群需要了解何种跌倒会导致损伤和骨折。在跌倒的老年人中，大多数人的髋部骨矿物质密度已比峰值低几个标准差，跌倒严重程度（如向一侧跌倒并撞击髋部所反映的）和身体体型是髋部骨折的重要风险因素，涉及到一个完全被骨矿物质密度知识所忽略的风险领域。这些发现清楚地表明，与负荷和骨脆性相关的因素在髋部骨折的病因中都起着重要作用。我们基于骨折风险预测的工程方法提供一种策略，以确定负荷和骨脆性在病因学上的相对重要性，并总结关于这两组因素的一些已知情况。我们将风险因素phi定义为施加于髋部的负荷与导致骨折所需负荷的比值，并总结phi分子和分母的现有数据。然后我们概述跌倒起始、下落和撞击阶段相关风险之间的复杂相互作用，从而提出一种有组织的方法来评估用于预防髋部骨折的干预措施。这些发现强调持续需要综合干预策略，该策略应侧重于预防跌倒、降低跌倒严重程度以及通过有针对性的运动计划、最佳营养（钙、维生素D）和/或使用骨动力药物来维持或增加股骨骨量和强度。通过开发和完善风险因素，这一既能体现骨密度的作用又能反映身体体型和跌倒严重程度混杂影响的特性，我们相信这些干预策略能够更精准地靶向实施。
