不同胫骨后倾角下两种方法重建ACL有限元分析

Finite Element Analysis of Two Methods of ACL Reconstruction under Different Posterior Tibial Slope

摘要: 目的：探索不同PTS对两种不同方法重建ACL及膝关节稳定性的生物力学影响。方法：选择一名健康志愿者行左侧膝关节CT及MRI扫描，测量胫骨平台后倾角为7˚，将数据导入计算机软件建立伸直位膝关节三维模型；建立2˚和12˚两种不同后倾角的膝关节伸直位三维模型，以及不同后倾角下不同屈伸状态模型。在不同屈伸角度的三种不同后倾角模型中，去除前叉韧带，按照ACL过顶位重建和解剖单束重建方法模拟重建，共重建出不同后倾角、不同屈膝状态下的模型18个，无ACL模型9个。将不同三维有限元模型导入ANSYS有限元分析软件中，给予加载负荷进行计算分析，在各模型中分析ACL所承受应力及胫骨-股骨之间的相对位移。结果：18个ACL重建模型和9个ACL缺失模型经有限元分析分别获得ACL所承受应力及胫骨-股骨相对位移，详细结果见正文。将各组分析结果进行对比，随着后倾角的增加，胫骨-股骨之间的位移逐渐增大，ACL承受的张力也增加，过顶位单束重建模型组的胫骨-股骨相对位移数据小于解剖单束重建，重建的ACL承受张力相对也低。结论：两种重建方法均能恢复膝关节的稳定性，无论解剖重建还是过顶位重建，随着PTS的增大，ACL承受的应力及胫骨-股骨之间的位移均会随之增大。在相同PTS下，解剖单束重建后出现旋转中心的下、内移，ACL力距变小，导致在相同负荷下ACL承受的张力、胫骨-股骨之间的位移均大于过顶位重建。

Abstract: Objective: To explore the biomechanical characteristics of reconstructed ACL and knee stability after reconstruction with different methods (over-the-top single bundle reconstruction (OSBR) and anatomical single bundle reconstruction (ASBR)). Methods: The left knee joint of a healthy volunteer was scanned by CT and MRI. The posterior tibial slope (PTS) is 7˚ degree measured on MRI scans. The data were imported into computer software to get the 3D models of the knee. The 3D models with 2˚ PTS and 12˚ PTS were established in Solidworks software. After establishment of three groups of knee extension model, 30 and 90 flexion models were made through Solidworks software. The ACLs were removed in three different PTS angle models. Then new ACLs were re-constructed respectively according to the technical requirements of OSBR and ASBR in Solidworks software (the tibial site was consistent and the femoral site was different in OSB group and ASB group). 18 models of different angles and of different reconstruction methods in different flexion were established, and 9 ACL deficient models were also established. Each 3D finite element knee models was imported into ANSYS software, and then given the load and analyzed by computer. The relative displacement between tibia and femur and the stress of ACL were recorded. Results: The stress and the relative displacement between tibia and femur were obtained by finite element analysis in 18 ACL reconstructed models and 9 ACL deficient models respectively. The detailed results were described in the text. The results were analyzed with different models. With the in-crease of tibia-femur displacement, the ACL tension increased compared with the increase of PTS. The results of the tibia-femur relative displacement and ACL tension in OSBR models were rela-tively low when compared with that in OSBR models. Conclusion: Both OSBR and ASBR can restore the stability of the knee joint. Regardless of anatomical single bundle reconstruction or over-the-top single bundle reconstruction, the stress of ACL and the displacement between tibia and femur will increase with the increase of the PTS. In the models with the same PTS, the rotation center moved inside near the condyle fossa after ASBR compared with that after OSBR, which resulted in short ACL force distance, so the tension of the ACL and the displacement between the tibia and the femur increase under the same load. This result is different from the previous studies and it is a question worth considering in the study of ACL reconstruction.