Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Via di Barbiano, 1/10, 40136 Bologna, Italy.
J Biomech. 2012 Feb 2;45(3):421-6. doi: 10.1016/j.jbiomech.2011.11.048. Epub 2011 Dec 26.
Elderly frequently present variable degrees of osteopenia, sarcopenia, and neuromotor control degradation. Severely osteoporotic patients sometime fracture their femoral neck when falling. Is it possible that such fractures might occur without any fall, but rather spontaneously while the patient is performing normal movements such as level walking? The aim of this study was to verify if such spontaneous fractures are biomechanically possible, and in such case, which conditions of osteoporosis, sarcopenia, and neuromotor degradation could produce them. To the purpose, a probabilistic multiscale body-organ model validated against controlled experiments was used to predict the risk of spontaneous fractures in a population of 80-years old women, with normal weight and musculoskeletal anatomy, and variable degree of osteopenia, sarcopenia, and neuromotor control degradation. A multi-body inverse dynamics sub-model, coupled to a probabilistic neuromuscular sub-model, and to a femur finite element sub-model, formed the multiscale model, which was run within a Monte Carlo stochastic scheme, where the various parameters were varied randomly according to well defined distributions. The model predicted that neither extreme osteoporosis, nor extreme neuromotor degradation alone are sufficient to predict spontaneous fractures. However, when the two factors are combined an incidence of 0.4% of spontaneous fractures is predicted for the simulated population, which is consistent with clinical reports. When the model represented only severely osteoporotic patients, the incidence of spontaneous fractures increased to 29%. Thus, is biomechanically possible that spontaneous femoral neck fractures occur during level walking, due to a combination of severe osteoporosis and severe neuromotor degradation.
老年人常表现出不同程度的骨质疏松、肌肉减少症和运动神经控制能力下降。严重骨质疏松症患者有时会在跌倒时骨折股骨颈。是否有可能在没有任何跌倒的情况下发生这种骨折，而是在患者进行正常运动（如平地行走）时自发发生？本研究旨在验证这种自发性骨折是否在生物力学上是可能的，如果是这样，哪种骨质疏松症、肌肉减少症和运动神经退化的情况会导致这种骨折。为此，使用经过对照实验验证的概率多尺度身体-器官模型来预测具有正常体重和肌肉骨骼解剖结构的 80 岁女性人群中自发性骨折的风险，这些女性具有不同程度的骨质疏松症、肌肉减少症和运动神经控制能力下降。多体逆动力学子模型与概率神经肌肉子模型以及股骨有限元子模型相结合，构成了多尺度模型，该模型在蒙特卡罗随机方案中运行，其中各种参数根据明确定义的分布随机变化。该模型预测，单独的极端骨质疏松症或极端运动神经退化都不足以预测自发性骨折。然而，当这两个因素结合在一起时，预测模拟人群中的自发性骨折发生率为 0.4%，这与临床报告一致。当模型仅代表严重骨质疏松症患者时，自发性骨折的发生率增加到 29%。因此，由于严重骨质疏松症和严重运动神经退化的结合，在平地行走时发生自发性股骨颈骨折在生物力学上是可能的。
