目的 探究唐氏综合征患儿站立时足部内结构的关节接触力、韧带拉力和力传导模式。方法 基于1名唐氏综合征患儿与1名典型健康儿童的CT影像学数据，分别建立足部有限元模型，采用静态站立下的足底压力分布实测数据验证模型。模拟站立时足踝受力，以地面反力和小腿三头肌肌力作为加载条件，计算分析胫距和跗横关节（距舟、跟骰）的关节接触压力、弹簧韧带和足底短韧带的拉力，以及跗横关节处的力传导模式。结果 足部有限元模型可靠且有效。与健康儿童相比，患儿胫距关节的接触压力更高（0.81 VS 0.61 MPa），距舟关节的接触压力更低（0.34 VS 0.64 MPa）； 患儿弹簧韧带和足底短韧带的拉力分别是健康儿童的10倍和58倍；患儿跗横关节的关节间力均小于正常儿童。结论 唐氏综合征患儿站立时存在异常的胫距关节接触压力、较大的中足韧带拉力及较小的跗横关节传导力。临床康复应充分考虑唐氏综合征患儿足部内结构应力模式的异常变化，为筛选和制定早期康复介入计划和设计个性化矫形鞋垫提供理论支撑。
Objective The purpose of this study was to explore the joint contact force, ligament tension and force conduction mode of foot internal structure in Down syndrome children (DSC) during standing. Methods Two three-dimension finite element foot models were constructed based on the CT of the DSC and typically developing children (TDC). The model validation was conducted by comparing the plantar pressure in finite element analysis with in-vivo plantar pressure measurement from the same participants during standing. To simulate standing, the ground reaction force of standing and the triceps surae force were taken as the loading condition. The analysis outcomes included: the contact pressure of the tibiotalar, talonavicular, and calcaneocuboid joints, tensile force of spring and plantar calcaneocuboid ligaments, and force transmission in transverse tarsal joints. Results The finite element models of foot were validated and reliable. Compared with the TDC, the DSC showed higher contact pressure at the tibiotalar joint (0.81 vs 0.61 MPa) and lower contact pressure at the talonavicular joint (0.34 vs 0.64 MPa). The tensile force of spring and plantar calcaneocuboid ligaments of DSC was 10 times and 58 times of TDC, respectively. The forces transmitted through both mediate and lateral columns in DSC was lower than those in TDC. Conclusions The abnormal contact pressure of tibiotalar joint, larger tension of midfoot ligaments and smaller force of transverse tarsal joint were found in DSC during standing. The abnormal alteration of stress pattern in the foot of DSC should be fully considered in clinical rehabilitation to screen early rehabilitation interventions and design orthopedic insoles.