Hayes W C, Myers E R
Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
Instr Course Lect. 1997;46:431-8.
Falls and fall-related hip fractures are among the most serious, common, and costly medical problems facing the elderly. Recently, we and others have shown that falls to the side, particularly those that end with impact on the hip, raise the risk of hip fracture from six- to thirty-fold, compared to about threefold increases in risk associated with one SD reduction in BMD at the hip. And yet, despite the apparently crucial importance of sideways falls, little is known about the mechanics of falling to the side. In addition, while previous studies have helped identify those factors that place the elderly at high risk for falling and provided assessment procedures that can be used to identify those at risk for falls, as far as we are aware no previous work has successfully identified subjects at increased risk of falling to the side. Moreover, while rigorous, multifactorial fall prevention efforts have demonstrated moderate reductions in fall incidence, such programs are expensive and potentially inefficient in that they have not consistently demonstrated reductions in the numbers of injurious falls. While trochanteric padding systems show considerable promise for hip fracture prevention by reducing impact force, they involve difficult acceptance and compliance issues and will require large and rigorous clinical trials to demonstrate effectiveness. Finally, while it also appears that osteodynamic agents can be used to increase BMD at the hip and spine, little is known about the local structural consequences of these changes and, in particular, if they are sufficient to prevent hip fracture from a severe fall. The findings reviewed here thus emphasize the continuing need for combined intervention strategies that focus on fall prevention, on reductions in fall severity, and on maintaining or increasing bone mass and strength, either through targeted exercise programs or the use of osteodynamic agents. By developing and refining the factor of risk phi, 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. Based on such approaches and an improved understanding of the complex interplay between fall biomechanics and bone fragility in the etiology of hip fracture, there is hope that the growing worldwide epidemic of hip fractures among the elderly can be substantially abated.
跌倒及与跌倒相关的髋部骨折是老年人面临的最严重、最常见且成本最高的医疗问题之一。最近，我们及其他研究人员表明，向一侧跌倒，尤其是那些以髋部受到撞击告终的跌倒，会使髋部骨折风险提高6至30倍，相比之下，髋部骨密度每降低1个标准差，骨折风险仅增加约3倍。然而，尽管向一侧跌倒显然至关重要，但人们对其力学机制却知之甚少。此外，虽然先前的研究有助于确定使老年人面临高跌倒风险的因素，并提供了可用于识别跌倒风险人群的评估程序，但据我们所知，此前尚无研究成功识别出向一侧跌倒风险增加的个体。再者，尽管严格的多因素跌倒预防措施已证明可适度降低跌倒发生率，但此类项目成本高昂且可能效率低下，因为它们并未始终如一地证明可减少伤害性跌倒的数量。虽然转子部衬垫系统通过降低冲击力在预防髋部骨折方面显示出巨大潜力，但它们存在难以被接受和依从性方面的问题，且需要大规模严格的临床试验来证明其有效性。最后，虽然似乎骨动力药物可用于增加髋部和脊柱的骨密度，但对于这些变化的局部结构后果，尤其是它们是否足以预防严重跌倒导致的髋部骨折，人们却知之甚少。因此，此处综述的研究结果强调，持续需要采取综合干预策略，这些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锻炼计划或使用骨动力药物来维持或增加骨量和骨强度。通过开发和完善风险系数phi，这一既能反映骨密度的作用又能体现身体形态和跌倒严重程度的混杂影响的属性，我们相信这些干预策略能够得到更恰当的应用。基于此类方法以及对髋部骨折病因中跌倒生物力学与骨脆性之间复杂相互作用的更深入理解，有望大幅减轻全球范围内老年人髋部骨折不断增加的流行趋势。
