目的：双任务跳跃动作是目前预测运动中膝关节损伤的有效方法，但从目前的研究来 看，对双任务中不同干扰条件下膝关节生物力学特点之间的差异研究较少，缺乏对膝关节 内部结构受力特征的讨论。因此，本研究利用不同干扰条件设计五种双任务跳跃动作，并 通过 CT 和 MRI 影像建立膝关节有限元模型。旨在探讨不同双任务跳跃动作下膝关节生物 力学特征及内部结构的应力水平差异，深入了解双任务跳跃落地膝关节的损伤机制。 方法：于北京师范大学随机招募了 15 名健康男性大学生，年龄 23.5±1.8 岁，身高 179±3.92cm，体重 78.5±5.2kg。利用 E-Prime 软件采集不同认知任务的反应时和准确率， 设计认知干扰下的双任务跳跃模式，利用头顶标记物设计动作干扰下的双任务跳跃模式。 采用 Vicon 红外捕捉系统以及 Kistler 测力台同步采集测试对象的运动学及力学数据，结 果导入 Visual 3D 软件进行逆向动力学计算。选取 1 名受试者，年龄 22 岁，身高 181cm， 体重 81kg，对其膝关节进行无负重下的 MRI 和 CT 扫描，利用 Mimics19.0 建立 3D 模型， 利用 Geomagic Wrap 进行二次平滑和几何修正创建实体模型，使用 Solid works2017a 构 建软组织结构，利用 Hypermesh14.0 进行各个结构的材料属性设定、网格划分、韧带线单 元添加等操作，将模型导入 Abaqus6.14a 进行有限元分析。根据垂直地面反作用力及角度 调整有限元模型的载荷和边界条件，得到膝关节内部结构接触应力特征。 结果：（1）触地瞬间不同条件下跳跃落地膝关节屈曲角度具有显著性差异；落地后 100ms 内不同条件间的运动学、动力学及跳跃表现均具有显著差异；（2）设定头顶目标时 髌骨软骨接触应力峰值最大，为 6.01Mpa，视觉干扰 5 条件下最小，为 5.02Mpa。不同条 件下跳跃落地股骨软骨的接触应力峰值均出现在内侧，其中设定头顶目标时股骨软骨接触 应力峰值最大，为 11.25Mpa，视觉干扰 5 条件最小，为 10.22Mpa。不同条件下跳跃落地 双侧半月板接触应力峰值均在内侧，双侧应力分布主要集中于内侧半月板体部偏上、外侧 半月板前角及外侧半月板体部偏上。不同条件下跳跃落地胫骨软骨接触应力峰值均较小， 其中设定头顶目标时外侧胫骨软骨的接触应力峰值最大，为 3.22Mpa，视觉干扰 5 条件最 小，为 2.52Mpa。 结论：（1）不同双任务跳跃动作落地膝关节生物力学特征具有差异，表现为，单一 认知任务反应时较长同时准确率较低时，膝关节发生损伤的风险越大。（2）设定头顶目 标下的双任务跳跃落地膝关节出现损伤的概率更高。（3）双任务跳跃落地膝关节损伤的 部位大多集中在内侧半月板及内侧股骨软骨。

Purpose: Dual-task jumping maneuvers are currently an effective method for predicting knee joint injury in sports, but from the current study, the differences between the biomechanical characteristics of the knee joint under different interference conditions in dual-task are less studied, and there is a lack of discussion on the force characteristics of the internal structures of the knee joint. Therefore, in this study, five dual-task jumping maneuvers were designed using different interference conditions, and finite element models of the knee joint were established by CT and MRI images. The aim was to investigate the biomechanical characteristics of the knee joint and the differences in stress levels of the internal structures under different dual-task jumping maneuvers, and to gain insight into the injury mechanisms of the knee joint under dual-task jumping maneuvers.Methods: Fifteen healthy male college students, age 23.5±1.8 years, height 179±3.92 cm, weight 78.5±5.2 kg, were randomly recruited at Beijing Normal University. four dual-task jumping patterns under cognitive interference were designed using E-Prime software to collect the reaction time and accuracy of different cognitive tasks, and one dual-task jumping pattern under action interference was designed using overhead markers. jumping mode using overhead markers. The kinematic and mechanical data of the test subjects were collected simultaneously using a Vicon infrared capture system and a Kistler dynamometer, and the results were imported into Visual 3D software for inverse kinetic calculations. One subject, age 22 years, height 181 cm, weight 81 kg, was selected to undergo MRI and CT scans of the knee joint without weight bearing, and a 3D model was created using Mimics 19.0, a solid model was created using Geomagic Wrap with secondary smoothing and geometric correction, a soft tissue structure was constructed using Solid works2017a, and a Hypermesh14.0 was used to set the material properties of each structure, mesh division, and ligament line cell addition, and the model was imported into Abaqus6.14a for finite element analysis. The load and boundary conditions of the finite element model were adjusted according to the knee joint reaction force and angle to obtain the contact stress characteristics of theinternal structure of the knee joint under different conditions. Results: (1) There were significant differences in knee flexion angle at the instant of landing touchdown of the jump under different conditions; there were significant differences in peak flexion angle, peak abduction angle and peak internal rotation angle within 100ms after landing; there were significant differences in peak ground reaction force, jump height and standing time; (2) The peak contact stress of patellar cartilage was the largest at 6.01Mpa when setting the overhead target, and the visual The peak contact stress of femoral cartilage in different conditions of jump landing was medial, with the peak contact stress of femoral cartilage being 11.25 MPa when setting the overhead target and 10.22 MPa when setting the visual interference 5 condition. The stress distribution was mainly concentrated in the upper part of the body of the medial meniscus, the anterior angle of the lateral meniscus and the upper part of the body of the lateral meniscus. The contact stress peaks of tibial cartilage in different conditions of jump landing were small, among which the contact stress peak of lateral tibial cartilage was the largest when setting the overhead target, 3.22 MPa, and the smallest in the visual interference 5 condition, 2.52 MPa. Conclusion: (1) The biomechanical characteristics of the knee joint with different dual-task jumping maneuvers on the ground differed, as demonstrated by the greater risk of knee joint injury when the response time of a single cognitive task was longer while the accuracy rate was lower. (2) Dual-task jumps with overhead targets landed with the highest peak contact stress on the internal cartilage structures of the knee joint, and the probability of knee injury was higher in this condition compared to other dual-task jumps. (3) The additional task could increase the impact load at the knee joint on landing and increase the risk of knee injury, which was mostly concentrated in the medial meniscus and medial femoral cartilage.