Mechano-biology of bone regeneration

骨痂牵引是一种外科技术，广泛用于矫形外科手术，例如骨延长或缺损愈合。尽管这种治疗在过去几十年中已经得到了改进，但仍然存在很高的并发症发生率，主要是由于不合适的生物力学条件，运动过多和组织应变过高。为了优化骨再生，必须进一步优化固定器械和牵引方案。一个先决条件是更好地理解机械信号对骨形成的影响（机械生物学）。为了使这些知识对患者有用，需要数值模拟模型来计算不同临床条件下固定稳定性对骨再生的影响。现有数值模型的一个重要限制是，它们不是基于可靠的数据，而是基于关于发育中的组织再生的材料性质、作用于骨再生部位的机械信号和机械生物组织分化规则的假设。该建议旨在通过优化机械-生物组织分化规则来开发用于愈伤组织牵引的改进的数值模型。为此，我们将研究骨愈合下的独家拉伸，压缩和剪切应变，通过防止重叠的机械信号，从生理musculoastal负荷使用一个新的动物模型，以前开发的我们的小组。此外，我们将测量愈合过程中再生组织的机械性能。机械条件的精确控制将允许通过机械和组织学数据的相关性来改进机械-生物组织分化规则。新的信息将在我们现有的外侧骨痂牵引数值模型中实现。将使用体内测量的机械组织特性的数据来校准模型。然后进行参数研究。将模拟不同方向和幅度的骨折块间运动，并评价其是否对骨愈合至关重要。本研究的结果将是开发强大的骨折愈合和骨痂牵引模型的重要一步，以计算不同临床条件下固定稳定性对骨再生的影响。

Callus distraction is a surgical technique, which is widely used in orthopaedic surgery for e.g. bone lengthening or defect healing. Although this treatment has been improved in the last decades, there is still a high rate of complications mainly due to unsuitable biomechanical conditions with too much movement and too high tissue strain. To optimize bone regeneration, the fixation devices as well as the distraction protocols have to be further optimized. A prerequisite is the better understanding of the effects of mechanical signals on bone formation (mechano-biology). To make this knowledge useful for the patients, numerical simulation models are needed to calculate the effect of the fixation stability on bone regeneration under different clinical conditions. An important limitation of existing numerical models is, that they are not based upon reliable data but upon assumptions in terms of the material properties of the developing tissue regenerate, the mechanical signals acting at the site of bone regeneration and the mechano-biological tissue differentiation rules.Therefore, this proposal aims to develop an improved numerical model for callus distraction by the optimization of the mechano-biological tissue differentiation rules. For this we will study bone healing under exclusive tensile, compression and shear strain by preventing overlapping mechanical signals from physiological musculoskelettal loading using a new animal model previously developed by our group. Furthermore, we will measure the mechanical properties of the tissue regenerate during the healing process. The exact control of the mechanical conditions will allow improvement of the mechano-biological tissue differentiation rules by the correlation of the mechanical and histological data. The new information will be implemented in our existing numerical model for lateral callus distraction. The model will be calibrated using the data of the mechanical tissue properties measured in vivo. Then a parametric study will be performed. Interfragmentary movements, which differ in direction and magnitude, will be simulated and evaluated as to whether they are critical or not for bone healing. The outcome of this study will be an important step forward in the development of powerful numerical fracture healing and callus distraction models to calculate the effect of the fixation stability on bone regeneration under different clinical conditions.