| Objective:To construct a human musculoskeletal model with the help of LifeMod simulation software,to obtain kinematic and kinetic parameters of walking in hemiplegic patients through simulation,to analyze and understand the main abnormal gait characteristics of hemiplegic patients,to explore the influence of abnormal muscle strength on walking function and to clarify the abnormal muscle strength performance of the lower limb muscles during walking to provide data support for the subsequent multi-channel muscle electrical stimulation of patients.METHODS:The Vicon 3D capture system was used to acquire and record the gait data of the subjects.The actual kinematic data were acquired.And use the actual measurement data to build a human bone kinetic model with the help of Visual3D.The kinematic spatial and temporal parameters of the subject were calculated and output.Then,with the help of LifeMod kinetic simulation software,five hemiplegic patients and six normal adults simulation models were constructed,and the models were driven to move.The kinetic data were calculated and output from the simulations.The kinematic and kinetic related parameters were compared between the two groups to analyze the abnormal characteristics of the patients and their internal mechanical response.RESULTS:1.Step length,step speed,step width,support time,support phase,and single step period on the affected side showed differences compared to normal subjects p<0.05.Step length,support phase,and support time,differed between the affected and healthy sides p<0.05.2.A more typical patient with hemiplegia was selected to analyze joint angles and joint moments compared to normal subjects.position compared to the affected side in normal subjects.The ankle joint moments in the sagittal plane were inadequate in dorsiflexion during the landing phase and plantarflexion during the swing phase.The knee joint was hyperflexed and limited in motion,and the knee extension moment was activated and insufficient during the support phase.During the swing phase,the moment's modulating effect on the knee joint was not reflected.Hip flexion and extension were limited,and the moment change tended to be zero throughout the phase.3.The vertical reaction force in the hemiplegic group was generally smaller than that in the normal group p<0.05,and the time interval between the two peak reaction forces was shorter in patients,and the second peak reaction force did not appear in three patients.Similarly,joint forces were generally less in all segments than in normal subjects,but the ankle joint was most significantly affected p<0.05.The knee joint was responsible for most of the body weight.4.Muscle strength simulations showed that compared to the normal group on the affected side;there were differences in the mean maximum muscle strength of the anterior tibialis,hallux valgus,lateral gastrocnemius,lateral femoral,biceps,rectus femoris,gluteus medius1 and the psoas major and adductor muscles p<0.05.5.0.05.5.Further breakdown of the patients revealed that the anterior tibialis,lateral gastrocnemius,gluteus maximus 2,and gluteus medius 1 were significantly smaller in the low velocity patients than in the medium velocity hemiplegic patients.CONCLUSION:Five small sample hemiplegic models and six normal adult models were constructed by simulation modeling software,and comparative analysis of kinematic and kinetic parameters obtained from simulation calculations led to the following conclusions.1.by the comparative analysis of the kinematic parameters with the normal group we found that;the step speed,step length and step frequency of the patients decreased and the step width increased after hemiplegia.On the time characteristics the single support time on the affected side was shortened and the double support time was prolonged.The proportion of support time on the healthy side increased significantly.The main abnormalities in the angles of the joints of the lower limbs,compared to normal people with hemiplegia on the affected side,were the joint angles at the initial landing,the maximum joint angles and the range of motion of the joints.In addition to muscle strength,the effect of muscle synergy on posture should not be neglected,and the patient's specific abnormal posture needs to be explained by specific joint parameters.2.The muscle strength simulation data showed that the muscle strength of the lower limbs of patients with muscle weakness hemiplegia varied greatly among individuals,but from the whole gait phase,the damaged muscles of different patients had some commonality,such as the muscles that showed differences in muscle strength of the affected lower limbs compared with the normal group were:anterior tibialis 0.12 N-kg-1,short head of biceps femoris 0.39 N-kg-1,hallux valgus 0.11 N·kg-1and iliopsoas0.11 N·kg-1of the hip.kg-1 and the iliopsoas muscle of the hip 1.28 N·kg-1These muscles all accounted for only about 33%of the average maximum muscle strength of the normal group.The short head of the biceps femoris 0.39 N·kg-1was less than 10%of the average maximum muscle strength of the normal group.The lateral femoral muscle 0.03 N·kg-1was largely inactive throughout the phase.In addition to these muscles that showed more generalized damage,there were also differences in the strength of each muscle from patient to patient.Patients with high stride speed had more normal muscle strength compared to patients with low stride speed.3.The results of the simulation calculation of the human musculoskeletal model constructed by Lifemod can truly reflect the activity intensity of each muscle of the lower limb during walking and output the muscle strength of the main muscles during walking of the lower limb,which can provide data support for the patient's future muscle multi-channel functional electrical stimulation training by clarifying the differences of each muscle. |
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