3D-Surgery, Department of General, Trauma and Reconstructive Surgery, University Hospital LMU Munich, Munich, Germany; Biomechanics and Implant Technology Research Laboratory, University Medicine Rostock, Rostock, Germany.
Department of General, Trauma and Reconstructive Surgery, University Hospital LMU Munich, Munich, Germany.
J Mech Behav Biomed Mater. 2022 Apr;128:105133. doi: 10.1016/j.jmbbm.2022.105133. Epub 2022 Feb 18.
In distraction osteogenesis (DO) of long bones, new bone tissue is distracted to lengthen limbs or reconstruct bone defects. However, mechanical boundary conditions in human application such as arising forces are mainly based on limited empirical data. Our aim was the numerical determination of the callus distraction force (CDF) and the total distraction force (TDF) during DO in the tibia of adults to advance the understanding of callus tissue behavior and optimize DO procedures.
We implemented a mathematical model based on an animal experiment to enable the calculation of forces arising while distracting callus tissue, excluding the influence of surrounding soft tissue (muscles, skin etc.). The CDF progression for the distraction period was calculated using the implemented model and varying distraction parameters (initial gap, area, step size, time interval, length). Further, we estimated the CDF based on reported forces in humans and compared the results to our model predictions. In addition, we calculated the TDF based on our CDF predictions in combination with reported resisting forces due to soft tissue presence in human cadavers. Finally, we compared the progressions to in vivo TDF measurements for validation.
Due to relaxation, a peak and resting CDF is observable for each distraction step. Our biomechanical results show a non-linear degressive increase of the resting and peak CDF at the beginning and a steady non-linear increase thereafter. The calculated resting and peak CDF in the tibial metaphysis ranged from 0.00075 to 0.0089 N and 0.22-2.6 N at the beginning as well as 20-25 N and 70-75 N at the end of distraction. The comparison to in vivo data showed the plausibility of our predictions and resulted in a 10-33% and 10-23% share of resting CDF in the total resting force for bone transport and elongation, respectively. Further, the percentage of peak CDF in total peak force was found to be 29-58% and 27-55% for bone transport and elongation, respectively. Moreover, our TDF predictions were valid based on the comparison to in vivo forces and resulted in a degressive increase from 6 to 125 N for the peak TDF and from 5 to 76 N for the resting TDF.
Our approach enables the estimation of forces arising due to the distraction of callus tissue in humans and results in plausible force progressions as well as absolute force values for the callus distraction force during DO. In combination with measurements of resisting forces due to the presence of soft tissue, the total distraction force in DO may also be evaluated. We thus propose the application of this method to approximate the behavior of mechanical callus properties during DO in humans as an alternative to in vivo measurements.
在长骨的牵张成骨术（DO）中，通过牵拉新骨组织来延长肢体或重建骨缺损。然而，人体应用中的力学边界条件，如产生的力，主要基于有限的经验数据。我们的目的是数值确定成人胫骨 DO 过程中的骨痂牵张力（CDF）和总牵张力（TDF），以深入了解骨痂组织的行为，并优化 DO 过程。
我们基于动物实验实施了一个数学模型，能够计算牵拉骨痂组织时产生的力，而不考虑周围软组织（肌肉、皮肤等）的影响。使用实施的模型并改变牵张参数（初始间隙、面积、步长、时间间隔、长度）来计算牵张期的 CDF 进展。进一步，我们根据报告的人类力来估计 CDF，并将结果与我们的模型预测进行比较。此外，我们根据我们的 CDF 预测并结合报告的人类尸体中软组织存在的阻力来计算 TDF。最后，为了验证，我们将进展与体内 TDF 测量进行了比较。
由于松弛，每个牵张步骤都会观察到峰值和静止 CDF。我们的生物力学结果表明，在开始时，静止和峰值 CDF 呈非线性递减增加，此后呈稳定的非线性增加。胫骨干骺端计算的静止和峰值 CDF 在开始时为 0.00075 至 0.0089 N 和 0.22-2.6 N，在结束时为 20-25 N 和 70-75 N。与体内数据的比较表明了我们预测的合理性，并导致骨搬运和延长的总静止力中静止 CDF 的比例分别为 10-33%和 10-23%。此外，峰值 CDF 在总峰值力中的百分比分别为骨搬运和延长的 29-58%和 27-55%。此外，我们的 TDF 预测基于与体内力的比较是有效的，并导致峰值 TDF 从 6 到 125 N 以及静止 TDF 从 5 到 76 N 的递减增加。
我们的方法能够估计由于人类骨痂组织牵张而产生的力，并产生合理的力进展以及 DO 过程中骨痂牵张力的绝对值。结合软组织存在产生的阻力测量，也可以评估 DO 中的总牵张力。因此，我们建议将该方法应用于近似人类 DO 过程中机械性骨痂特性的行为，作为体内测量的替代方法。
