van der Linden J C, Homminga J, Verhaar J A, Weinans H
Department of Orthopedics, Erasmus University Medical Center Rotterdam, The Netherlands.
J Bone Miner Res. 2001 Mar;16(3):457-65. doi: 10.1359/jbmr.2001.16.3.457.
The skeleton is continuously being renewed in the bone remodeling process. This prevents accumulation of damage and adapts the architecture to external loads. A side effect is a gradual decrease of bone mass, strength, and stiffness with age. We investigated the effects of bone loss on the load distribution and mechanical properties of cancellous bone using three-dimensional (3D) computer models. Several bone loss scenarios were simulated. Bone matrix was removed at locations of high strain, of low strain, and random throughout the architecture. Furthermore, resorption cavities and thinning of trabeculae were simulated. Removal of 7% of the bone mass at highly strained locations had deleterious effects on the mechanical properties, while up to 50% of the bone volume could be removed at locations of low strain. Thus, if remodeling would be initiated only at highly strained locations, where repair is likely needed, cancellous bone would be continuously at risk of fracture. Thinning of trabeculae resulted in relatively small decreases in stiffness; the same bone loss caused by resorption cavities caused large decreases in stiffness and high strain peaks at the bottom of the cavities. This explains that a reduction in the number and size of resorption cavities in antiresorptive drug treatment can result in large reductions in fracture risk, with small increases in bone mass. Strains in trabeculae surrounding a cavity increased by up to 1,000 microstrains, which could lead to bone apposition. These results give insight in the mechanical effects of bone remodeling and resorption at trabecular level.
在骨重塑过程中，骨骼不断更新。这可防止损伤积累，并使骨骼结构适应外部负荷。一个副作用是随着年龄增长，骨量、强度和硬度会逐渐下降。我们使用三维（3D）计算机模型研究了骨质流失对松质骨负荷分布和力学性能的影响。模拟了几种骨质流失情况。在高应变位置、低应变位置以及整个结构中随机去除骨基质。此外，还模拟了吸收腔和小梁变薄的情况。在高应变位置去除7%的骨量会对力学性能产生有害影响，而在低应变位置可去除高达50%的骨体积。因此，如果重塑仅在可能需要修复的高应变位置启动，松质骨将持续面临骨折风险。小梁变薄导致刚度相对较小的降低；由吸收腔导致的相同骨量流失会导致刚度大幅降低以及腔底部出现高应变峰值。这解释了抗吸收药物治疗中吸收腔数量和大小的减少可导致骨折风险大幅降低，而骨量仅有小幅增加。腔周围小梁中的应变增加高达1000微应变，这可能导致骨附着。这些结果有助于深入了解小梁水平骨重塑和吸收的力学效应。
