| Objective:The ankle joint is an important joint of the human body.The activities of daily life and physical activities require the participation of the ankle joint.Ankle joints are susceptible to get hurt,and ankle fractures are the most common lower limb fractures.Among the many types of ankle fractures,the incidence of trimalleolar fractures has a rising trend and a poor prognosis,accompanying with some complications such as arthritis.The current researches mainly focus on trimalleolar fractures through scales,medical imaging and other methods.There are few studies concerning on exercise biomechanics in patients with trimalleolar fractures,and there are no studies about the ankle stability and motor control capacity of trimalleolar fractures patients in different stress positions(Ankle neutral position,Ankle inversion,Ankle eversion).This article combined the commonly used clinical assessment with exercise biomechanics research,aiming to compare the ankle joint motion characteristics and regularity between patients with trimalleolar ankle fractures and healthy subjects,and also analyzed the correlation between the results of clinical evaluation,biomechanical evaluation and the performance of walking function,to further explore the characteristics of patients with trimalleolar fractures and influential factors of motor function,so as to provide effective and accurate theoretical guidance for post-operative rehabilitation of trimalleolar fractures patients.Methods:12 patients with trimalleolar fractures were recruited as the experimental group and 23 healthy subjects without ankle injury were recruited as the control group.The subjects in both groups completed walking at three stress positions,and plantar pressure and surface electromyography signals of lower limbs were collected:the walking in the stress positions of ankle inversion and eversion were completed by simple customized walkway(with an inclination of 10°),the walking in the neutral ankle position was completed on flat ground,the plantar pressure at different stress positions was collected by plantar pressure system(100Hz,Novel GmbH,Munich,Germany),and the surface electromyography signals of different stress positions were collected by the Noraxon surface EMG(1500HZ,Noraxon DTS,USA).The gait parameters of two groups were collected by Vicon motion capture system(200HZ,ViconT40,Oxford Metrics,Oxford,UK)and three-dimensional force platform(2000HZ,Kistler).The proprioception of the two groups members was evaluated by Prokin(Technobody-PK254,Italy).The experimental group also completed the related clinical evaluations:ankle swelling,lower limb muscle strength,active range of motion of ankle joint,Lawton IADL scale and Olerud Molander scale.SPSS 23.0 statistical software and Microsoft Excel 2016 were used to analyze data.The form of mean±standard deviation was used for all measurement data.2×3 two factor analysis of variance was used to analyze the plantar pressure and sEMG signals of bilateral lower limbs in three stress positions;the paired sample t test was used to analyze the results of Prokin test and gait test on both sides of the two groups;the results of Prokin test,gait parameters,plantar pressure data and sEMG signals were analyzed by independent sample t-test.Pearson correlation analysis was used to analyze the correlation between clinical evaluation results,biomechanics and walking performance of patients.The closer the absolute value of correlation coefficient r is to 1,the higher the closeness is.The significance level was set at P<0.05.Results:(1)The features of dynamic plantar pressure of different stress positions:a)Healthy subjects:The peak pressures in the M1 and T345 regions of plantar of inversion position were greater than that of neutral position,while in M4,M5 and T345,the peak pressures of the inversion position were greater than that of the neutral position.There were no significant difference in the total contact area among the three stress positions.The total contact time of neutral,inversion and eversion position were794.98±18.30ms,849.46±15.72ms and 843.21±16.37ms respectively,with significant difference between inversion and neutral position(P=0.038).There were significant differences in M/L(ratio of peak pressure of medial and lateral regions)and A/P(ratio of peak pressure of forefoot and hindfoot)at different stress positions(P<0.001).M/L of inversion,neutral and eversion position were 1.24±0.46,1.06±0.26,0.88±0.25,while A/P of inversion,eversion and neutral position were 1.64±0.22,1.62±0.32,and 1.44±0.18 respectively.b)The subjects with trimalleolar fractures:The characteristics of plantar pressure on the affected sides and the healthy sides were as follows:the peak pressure of M2,M3,T2 and T345 on the affected sides were significantly lower than those on the healthy side.The total contact area of the affected sides and the healthy sides were102.46±13.29cm~2 and 112.47±22.26cm~2,P=0.032.The percentage of contact time of HF on the affected sides was significantly higher than that on the healthy sides(P=0.044),while the percentage of contact time of M1,M2,T2 and T345 were significantly lower than those on the healthy sides.There were significant differences in the M/L and A/P of both limbs(P=0.034,0.028,respectively).The M/L of the affected sides was 0.80±0.25,and that of the healthy sides was 0.98±0.39,the A/P of the affected sides was 1.12±0.58,and that of the healthy sides was 1.42±0.44.The features of plantar pressure of the subjects with trimalleolar fractures of three stress positions were as follows:there were significant differences in the total contact time of the three stress positions,P=0.004.The total contact time of neutral,inversion and eversion position were 1022.27±152.38ms,1265.83±211.20ms,and 1073.70±169.72ms respectively.There was no significant difference in M/L and A/P of different stress positions,and the P values were 0.252 and 0.894 respectively.c)Comparative analysis of the features of plantar pressure in the two groups:It was found that the peak pressures in the M2,M3,T2 and T345 plantar regions of the patients were significantly lower than those of the healthy subjects at the three stress positions.In eversion position,the total foot contact area of the patients was significantly smaller than that of the normal group.For patients,the percentage of contact time in the T2 and T345 regions of the three stress sites were significantly lower than those of the normal group,and which in the HF and MF regions were significantly higher than those of the normal group;the total contact time of the three stress positions were significantly higher than that of the normal group.(2)The features of surface EMG of different stress positions:a)Healthy subjects:There was no significant difference in the normalized IEMG of the dominant and non-dominant lower limb muscle groups in healthy subjects(P>0.05).At different stress positions,there were significant differences in the IEMG of tibialis anterior muscle,peroneus longus muscle and soleus muscle(P<0.05).b)The subjects with trimalleolar fractures:There was no significant difference in the normalized IEMG between the affected side and the healthy side,and the normalized IEMG of the medial gastrocnemius muscle was significantly lower in the eversion position than that in the inversion position.c)Comparative analysis of the features of sEMG in the two groups:At the three stress positions,the IEMG of the peroneus longus and lateral gastrocnemius muscle were significantly higher than that of the normal group,and in the ankle neutral position,the IEMG of the tibial anterior muscle was significantly higher than that of the healthy subjects.(3)Proprioception:There were no significant difference in ATE,AFV,standard deviation of trunk movement(anterior-posterior and left-right sides)of patients,and there was a significant difference in AFV between two lower limbs of healthy subjects(P=0.032).There was a significant difference in ATE between the two groups(P=0.042).(4)Spatio-temporal parameters of gait:There was no significant difference of the gait parameters of healthy subjects between the left and right sides;the step length of the affected side was larger than that of the healthy side(P=0.008),and the walking speed,single support period and weight-bearing of the affected side were smaller than that of the healthy side(P=0.041,0.038 and 0.043 respectively).The patient's step length was smaller than that of the normal group(P<0.001),the patient's step width was larger than that of the normal group(P=0.021),the patient's walking speed was smaller than that of the normal group(P<0.001),and the single support period had no significant difference between the two groups(P=0.900).(5)Clinical evaluation and correlation studies:The affected side of the ankle was swollen with 1.4±0.6cm larger than the healthy side;The angles of dorsiflexion,plantar flexion,inversion and eversion on the affected side were all lower than those on the healthy side,and inversion angle had the greatest difference.Most of the subjects showed a decrease in the muscle strength of lower limbs.The total score of O&M scale was 56±11.26 points,and scores of stiffness,swelling,running,jumping and squatting scores were low.The total score of Lawton scale was 14.18±2.40 points,among which the scores of cleaning,shopping and housework activities were low.The results of correlation analysis showed that swelling was strongly and negatively correlated with the step length difference and the weight loading ratio of both sides,and the difference of inversion angles was strongly and positively correlated with the differences of step width and walking speed of both sides.The A/P of all three stress positions were positively correlated with walking performance,and there was a consistency between different parameters of plantar pressure and gait performance at the stress position of ankle eversion,while there was no obvious regularity at the stress position of ankle inversion and neutral positions.There was a negative correlation between walking performance and sEMG activity in soleus and medial gastrocnemius in ankle inversion position.In neutral position,sEMG of tibialis anterior muscle was negatively correlated with walking performance.Conclusions:(1)Biomechanical evaluation:The measurements result of plantar pressure and surface electromyography at different stress positions reveal that the stability and motion control ability of the affected ankle joints in the three stress positions are lower than that of healthy subjects.The muscle functions of peroneus muscles and the lateral gastrocnemius muscle of the affected lower limbs are decreased.The proprioception of patients is decreased;the supporting abilities of affected limbs are reduced;the walking speed was reduced and the gait is asymmetric.(2)Clinical evaluation:The scores of ankle joint motor function in scales are reduced.Most patients are currently unable to perform running and jumping activities and cannot complete heavy physical housework independently.For most of the patients with trimalleolar fractures,the affected ankle joints are swelling,the active range of motion of ankles are decreased.(3)Correlation study between clinical evaluation,sports biomechanics research and walking performance:The reduce of swollen,the improvement of ankle inversion and the improvement of the function of soleus,gastrocnemius and tibialis anterior muscles are helpful to enhance the gait symmetry.A/P and plantar pressure features during walking in ankle eversion position could be used for rehabilitation assessment of patients with trimalleolar fractures. |
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