Analysis Of Lower Limb SEMG And Joint Loading In Stance Phase In KOA Patients During Stair Negotiation

Objective: This case-control study investigated the lower limb muscle electromyography(EMG)and knee angular impulse in knee osteoarthritis(KOA)patients' stance phase by applying three-dimensional gait analysis during stair negotiation.To explore effects of recruitment status of lower limb muscle group and muscle co-activation pattern on knee joint loading in KOA patients.To provide reference for the establishment of rehabilitation strategies and the training of daily functional activities for KOA patients.Methods: Using the Qualisys 3D motion analysis system and the Delsys wireless surface EMG system,gait analysis was performed on 10 KOA patients and 10 normal persons who met the inclusion and exclusion criteria,analyzing EMG of the tibialis anterior(TA),gastrocnemius medial(MG),vastus lateralis(VL),vastus medialis(VM),hamstring lateralis(LH),gluteus maximus(GMAX),gluteus medius(GMED)and angular impulse of the knee on the frontal and sagittal plane.To explore the differences of muscle activation and recruitment status,activation time,activation level,co-activation pattern and the effect of contraction pattern on joint loading in stance phase between KOA patients and normal people during stair negotiation.Results:(1)Compared to the normal control,during ascending stairs,the Root Mean Square(RMS)of vastus medialis was decreased(P<0.01)and the RMS of gluteus maximus was increased in KOA patients(P<0.05).The RMS of vastus lateralis was significantly greater during descending stairs(P<0.01).No significant statistical difference was found in RMS values of other muscle groups(P>0.05).(2)The Integrated Electromyogram(i EMG)of the vastus lateralis,hamstring lateralis and gluteus maximus in KOA patients were greater than those of normal subjects during ascending stairs(P<0.05).IEMG in rectus femoris,medial gastrocnemius and hamstring lateralis of KOA patients was increased compared with normal subjects during descending stairs(P<0.05).No significant statistical difference was found in i EMG values of other muscle groups(P>0.05).(3)Compared to the normal control,the activation time of tibialis anterior decreased significantly and activation time of gluteus maximus and gluteus medius increased in stance phase for KOA patients during descending stairs(P<0.01).Activation of the vastus medialis was delayed compared to the vastus lateralis in KOA patients during descending stairs(P<0.01).There was no statistical difference in activation time of other muscle groups between KOA patients and normal subjects(P>0.05).(4)The co-activation ratio of the VM/VL in KOA patients was significantly lower than normal subjects during stair negotiation(P<0.01).The co-activation ratio of VL/LH in KOA patients was greater than that in normal patients during descending stairs(P<0.05).There was no statistical difference in other co-activation ratios(P>0.05).(5)The co-activation index of the LH:VL in KOA patients was significantly higher than normal subjects during ascending stairs(P<0.01).The co-activation index of the LH:VL and VM:MG in KOA patients was higher than normal subjects during descending stairs(P< 0.05),there was no statistical difference in other co-activation indexes(P>0.05).(6)The impulse of the knee joint in KOA patients on sagittal plane increased significantly during descending stairs(P<0.01).No other significant statistical differences were found(P>0.05).(7)There was a linear correlation between the co-activation index of VM:VL and the LH:VL(r=0.495,P<0.01),VM:VL and VM:MG(r=0.694,P<0.01)in KOA patients during ascending stairs.There was a linear correlation between the co-activation index of the VM:MG in KOA patients during descending stairs(r=0.784,P<0.01).No significant correlation was observed in normal subjects(P > 0.05).There was no significant correlation between the co-activation ratio of the muscle groups around the knee joint and the increase of joint impulse(P>0.05).Conclusion:(1)KOA Patients showed under-activation and delayed activation of the VM and compensatory activation of the VL in stance phase of gait during stair negotiation.Activation level and activation time of gluteus muscle increased in stance phase in KOA patients during descending stairs.(2)In KOA patients,Overall muscle activation strategies are used to stabilize the joint,while in normal people,selective activation strategies may be used to reduce the medial loading of the knee joint during stair negotiation.(3)Although the angular impulse of knee extension in KOA patients increased during descending stairs,there was no direct correlation between the co-activation of muscles and the knee impulse in KOA patients during stair negotiation,and it was possible that the co-activation of muscles was not the main biomechanical factor affecting the joint loading.