Wu Qiong, Zhang Yuanzhi, Wang Shaobai, Liu Rui, Liu Gang
Department of Radiology, The Affiliated Hospital of Inner Mongolia Medical University, Hohhot, People's Republic of China.
Department of Orthopaedics, The Affiliated Hospital of Inner Mongolia Medical University, Hohhot, People's Republic of China.
Indian J Orthop. 2022 Jun 1;56(8):1354-1362. doi: 10.1007/s43465-022-00656-x. eCollection 2022 Aug.
To evaluate the biomechanical performances of the sacroiliac screw fixation of the first sacral vertebra with different lengths of screws using the Finite-Element Method.
First, pelvic CT images were generated from a healthy volunteer, and multislice sagittal views were produced to determine the axis for the first sacral vertebra geometric osseous fixation pathway (GOFP). Subsequently, according to the geometric size and mechanical parameters of the iliosacral screw, the screw models with the same diameter of 7.3 mm and different lengths of 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm and 140 mm were built. Then the seven screws were assembled with the pelvic model. The maximum von Mises stress and the shape variables were evaluated for the pelvis and the screws.
Results are shown for the pelvic and GOFP screw, respectively. The simulation results show that the maximum von Mises stress in the cortex of the pelvic ring of the pelvis with the 130-mm length screw is the lowest among the pelvic models with different screws. Moreover, the peak displacement of the pelvis with the 130-mm length screw is the smallest. These results indicate that under the standing condition, a 130-mm length screw can decrease the stress concentration and result in a more effective transfer of stress within the reconstructed pelvis. In addition, the displacement of the screw with a 130-mm length is the smallest among all the considered screws. The peak von Mises stresses in the 130-mm length screw and the cortex are still within a low and elastic range below the yielding strengths of the materials.
Through the finite element analysis, the GOFP can be used as a safe and effective way for iliosacral screw fixation. The optimal length of the screw may be 130 mm length.
采用有限元方法评估不同长度螺钉对第一骶椎骶髂螺钉固定的生物力学性能。
首先，从一名健康志愿者获取骨盆CT图像，并生成多层矢状面视图以确定第一骶椎几何骨固定路径（GOFP）的轴线。随后，根据髂骶螺钉的几何尺寸和力学参数，构建直径均为7.3mm、长度分别为80mm、90mm、100mm、110mm、120mm、130mm和140mm的螺钉模型。然后将这七枚螺钉与骨盆模型进行组装。评估骨盆和螺钉的最大von Mises应力及形状变量。
分别给出了骨盆和GOFP螺钉的结果。模拟结果表明，在不同螺钉的骨盆模型中，使用130mm长螺钉时骨盆环皮质的最大von Mises应力最低。此外，使用130mm长螺钉时骨盆的峰值位移最小。这些结果表明，在站立状态下，130mm长的螺钉可降低应力集中，并在重建骨盆内实现更有效的应力传递。此外，在所有考虑的螺钉中，130mm长螺钉的位移最小。130mm长螺钉及其皮质中的峰值von Mises应力仍处于低于材料屈服强度的低弹性范围内。
通过有限元分析，GOFP可作为一种安全有效的髂骶螺钉固定方法。螺钉的最佳长度可能为130mm。
