基于足底模型的痉挛性脑性瘫痪儿童步态生物力学特征分析

Biomechanical Gait Analysis in Children with Spastic Cerebral Palsy Using Foot Sole Model

目的:基于足底模型分析尖足步态、蹲伏步态痉挛性脑性瘫痪(CP)儿童步态生物力学特征,探讨其与正常发育儿童步态生物力学特征的差异。方法:选择新西兰奥克兰大学生物力学实验室收集的60例CP儿童步态数据,按步态情况分为正常发育组、尖足步态组、蹲伏步态组,每组20例。采用三维步态采集与分析系统采集步态运动学数据。测试前先完成静态试验,校准计算机模型的物理标记点。每次测试时,研究对象以正常步速在指定区域内向前行进10 m,重复测量3次,取其平均值。比较3组足底压力中心前后侧(AP)位移、内外侧(ML)位移和中心位移斜率;踝关节最大推进力时足底压力中心与足底坐标系原点的水平距离(COP-AJC_(0));踝关节/膝关节AP、ML方向的杠杆臂和外力矩的差异。结果:(1)足底压力中心轨迹特征:与正常发育组比较,尖足步态组和蹲伏步态组COP-AJC_(0)均明显升高,差异均具有统计学意义(P<0.05)。与尖足步态组比较,蹲伏步态组COP-AJC_(0)、足底压力中心前后侧位移明显更大,足底压力中心位移斜率明显更小,差异均具有统计学意义(P<0.05)。(2)踝关节、膝关节杠杆臂和外力矩:与正常发育组比较,尖足步态组和蹲伏步态组踝关节AP杠杆臂、膝关节AP杠杆臂均明显更长,差异具有统计学意义(P<0.05)。与尖足步态组比较,蹲伏步态组踝关节AP杠杆臂明显更长,差异具有统计学意义(P<0.05)。3组踝关节/膝关节AP、ML外力矩差异均无统计学意义(P>0.05)。结论:基于改良足底模型的足底压力中心轨迹和下肢关节杠杆臂特征分析能够精确、客观地反映痉挛性脑瘫儿童步态生物力学特征,值得临床推广应用。

Objective: To analyze the biomechanical characteristics of equinus and crouch gait in children with spastic cerebral palsy(CP) using the foot sole model, and to compare the differences with the gait biomechanical characteristics of normal developing children. Methods: Gait data of 60 children with CP collected by the Biomechanics Laboratory of University of Auckland, New Zealand were selected and divided into normal developing group, equinus gait group and crouch gait group, with 20 cases in each group. A three-dimensional motion capture system was used to collect gait data. A static trial was first completed to calibrate the computerized model to each of the physical markers. In each test, the participant walked 10 meters at a self-selected pace along a 10-metre walkway. Three successful gait trials were obtained for each participant and the mean value was taken. The anteroposterior(AP) displacement, medial-lateral(ML) displacement and displacement slope of the plantar center of pressure(COP) were calculated and compared among the three groups. The distance between the center of pressure and the origin of foot sole coordinate system, and the ankle and knee lever arms and external moments in AP and ML directions at maximal propulsion were also compared among three groups. Results:(1) Characteristics of plantar center of pressure progression: compared with the normal developing group,COP-AJC_(0) significantly increased in the equinus gait group and the crouch gait group(P<0.05). Compared with the equinus gait group, the crouch gait group had an increased COP-AJC_(0), a greater anterioposterior displacement, and a lower center of pressure displacement slope(P<0.05).(2) The ankle and knee lever arms and external moments: compared with the normal developing group,the crouch gait group and the equinus gait group had longer anteroposterior lever arms around the knee and ankle joints(P<0.05).Compared with the equinus gait group, the crouch gait group showed longer anteroposterior lever arms of the ankle(P<0.05). There were no significant differences in AP and ML external moments of ankle and knee joints in the three groups(P>0.05). Conclusion:The analysis of plantar center of pressure progression and lever arm characteristics of lower extremity joints based on the foot sole model can accurately and objectively reflect the biomechanical characteristics of gait in children with spastic cerebral palsy, which is recommended for clinical application.