胫骨髓内钉治疗胫骨骨折扩髓与非扩髓的生物力学分析

Biomechanical Analysis of Reamed and Unreamed in Tibial Fractures Treated with Intramedullary Nails

摘要: 目的：通过有限元技术分析胫骨顺行髓内钉治疗AO/OTA 43-A3型胫骨远端骨折扩髓与非扩髓的力学分布特点，证实两种手术方式的不同生物力学优势，为临床医师提供治疗方案的选择与指导。方法：选取一名健康志愿者，CT扫描其胫骨获取DICOM格式文件，导入Mimics软件中提取胫骨三维模型。使用Geomagic Wrap软件对胫骨三维模型进行多边形优化，通过精确曲面命令框操作获取胫骨实体初始模型，复制偏移得到松质骨实体模型。将其导入SolidWorks软件中通过布尔运算得到皮质骨模型，并将皮质骨与松质骨进行装配得到胫骨实体模型，在模型上绘制骨折线并截骨得到AO/OTA 43-A3骨折模型，绘制2组髓内钉模型A组：直径10 mm、长度360 mm的髓内钉模拟非扩髓；B组：直径12 mm、长度360 mm髓内钉模拟扩髓。将胫骨骨折模型分别于2组髓内钉进行装配。将两组2组模型分别导入Ansys软件中分析求解。观察2组模型中胫骨及髓内钉的位移情况和应力分布。结果：1) 在AO/OTA 43-A3型骨折中胫骨与髓内钉应力及位移集中部位并不会受到所固定髓内钉直径的影响；2) 在AO/OTA 43-A3型骨折中，采用未扩髓组髓内钉固定胫骨时，胫骨与髓内钉最大应力值及位移值均大于扩髓组。结论：采用胫骨顺行髓内钉治疗AO/OTA 43-A3型胫骨远端骨折中，扩髓髓内钉固定方案体现出更好的生物力学性能。

Abstract: Objective: The mechanical distribution characteristics of reamed and unreamed in the treatment of AO/OTA 43-A3 type distal tibial fractures by intramedullary nails were analyzed through finite element technology. The different biomechanical advantages of the two surgical methods were con-firmed to provide clinicians with the selection and guidance of treatment plans. Method: A healthy volunteer was selected. The tibia was scanned by CT to obtain the DICOM format file, which was im-ported into the Mimics software to extract the three-dimensional model of the tibia. The Geomagic Wrap software was used to optimize the polygon of the three-dimensional tibia model. The initial tibial solid model was obtained through the operation of the precise surface command box, and the cancellous bone solid model was obtained by replication and offset. The cortical bone model was obtained through a Boolean operation in SolidWorks software, and the cortical bone was integrated with cancellous bone to obtain the tibial solid model. Fracture lines were designed on the model and osteotomy was performed to obtain the AO/OTA 43-A3 fracture model. Two groups of intramedul-lary nail models were drawn. Group A: An intramedullary nail with a diameter of 10 mm and a length of 360 mm simulated unreamed expansion. Group B: An intramedullary nail with a diameter of 12 mm and a length of 360 mm simulated reamed expansion. The tibial fracture models were assembled with intramedullary nails in the two groups respectively. The two groups of models were respectively imported into the ANSYS software for analysis and solution. Observe the displacement and stress distribution of the tibia and intramedullary nails in the two groups of models. Result: 1) In AO/OTA 43-A3 type fractures, the stress and displacement concentration areas of the tibia and intramedullary nail are not affected by the diameter of the fixed intramedullary nail; 2) In AO/OTA 43-A3 type fractures, when the tibia is fixed with an intramedullary nail in the unreamed group, the maximum stress and displacement values of the tibia and intramedullary nail are greater than those in the reamed group. Conclusion: In the treatment of AO/OTA 43-A3 type distal tibial frac-tures with antegrade intramedullary nails, the reamed intramedullary nail fixation scheme demonstrates better biomechanical performance.