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Objective:To investigate the correlation of isokinetic thigh muscle asymmetry with gait asymmetry at one year after anterior cruciate ligament (ACL) reconstruction.Methods:A retrospective case series analysis was made on 25 patients treated by ACL reconstruction in Third Hospital of Peking University from January 2014 to January 2019. All the subjects were male, aged 17-47 years [(29.4±5.2)years]. Standard rehabilitation treatment procedures were conducted after surgery. The isokinetic muscle strength of the thigh was collected at one year after operation to evaluate knee extensor and flexor concentric strength at 60°/s, 180°/s and 300°/s, and knee extensor and flexor eccentric strength at 60°/s. The maximum concentric and eccentric strength of the knee extensor and flexor were analysed between the injured and intact side. The three-dimensional motion information and ground reaction force was collected during the stance phase of gait, and knee kinematic and kinetic parameters were calculated by inverse dynamics analysis, including the peak flexion moment, peak extension moment, first and second peak adduction moment, peak external and internal rotation moment, peak flexion angle, peak extension angle during the terminal stance phase, flexion angle at heel strike, peak abduction angle, and peak external rotation angle during terminal stance phase. Spearman correlation analysis was used to study the correlation between limb symmetry index (LSI) of isokinetic muscle strength and LSI of gait parameters.Results:One year after ACL reconstruction, the maximum concentric strength of the knee extensor and flexor at 60°/s, 180°/s and 300°/s and maximum eccentric strength of the knee flexor and extensor at 60°/s on the injured side were significantly lower than those on the normal side (all P<0.01). Compared with the intact side, the peak knee extension moment on the injured side was significantly lower during the stance phase of gait ( P<0.01), and the extension angle was insufficient during the terminal stance phase ( P<0.01). There were no significant differences between the injured and intact side in terms of peak flexion moment, first and second peak adduction moment, peak external and internal rotation moment, peak flexion angle, flexion angle at heel strike, peak abduction angle, and peak external rotation angle during terminal stance phase (all P>0.05). One year after ACL reconstruction, Spearman correlation analysis during gait stance phase showed that the LSI of 60°/s concentric strength of the isokinetic knee extensor was significantly related to LSI of peak internal rotation moment ( R=0.42, P<0.05), the LSI of 180°/s concentric strength of the isokinetic knee extensor was significantly related to LSI of peak flexion moment ( R=0.45, P<0.05), the LSI of 180°/s concentric strength of the isokinetic knee flexor was significantly correlated with LSI of peak flexion angle ( R=0.46, P<0.05), the LSI of 300°/s concentric strength of the isokinetic knee extensor was significantly correlated with LSI of peak knee flexion angle ( R=0.42, P<0.05), and the LSI of 60°/s eccentric strength of the isokinetic flexor was significantly correlated with LSI of peak knee flexion angle ( R=0.54, P<0.01). Conclusions:For patients following ACL reconstruction at one year postoperatively, a significant correlation of isokinetic thigh extensor strength asymmetry with peak knee flexion and rotation moment and peak knee flexion angle, and that of isokinetic thigh flexor strength asymmetry with peak knee flexion angle are observed during the stance phase of gait, which suggests that patients with ACL reconstruction still need systematic rehabilitation training one year postoperatively to improve muscle strength and motor function so as to reduce the risk of ACL reinjury and secondary injury.
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@#Objective Gait analysis plays an important role in the description of the site and degree of injury in the lower limbs, and symmetry is an important indicator of gait characteristics. The aim of this study is to quantitatively describe gait information and its asymmetry in three-dimensional space, dig deeper into gait information and improve the analysis of abnormal gait characteristics.Methods The information about the change of coronal-sagittal plane angle in different parts was obtained based on the inertial gait sensor, and the gait space vector was inverted to build the movement curve and form a motion symmetry detection method based on three-dimensional space angle vector distance. The characteristics of normal subjects (control group) and the anterior cruciate ligament (ACL) rupture patients (patients group) were analyzed from July, 2017 to January, 2018, and its effectiveness was verified.Results There was a better discrimination effect in the calf, thigh and knee asymmetry, etc., between the control group and the patient group (P<0.05). The characteristics of the calf space motion vector were highest among the control group and the patient group, and the discrimination was relatively stable, and not various with gender, age, height or body mass index.Conclusion The time-coronal-sagittal vector diagrams of left and right limbs were obtained by inertial sensor and the average of the square of the Euclidean distances in space at the selected gait cycle time points was calculated in three-dimensional space, which could be used as a gait asymmetry analysis method.