Preliminary Research On The Effect Of Ultrashort Wave Diathermy On Joint Dysfunction And Disuse Muscle Atrophy In A Rabbit Model Of Extending Knee Joint Contracture

Objective: To investigate the process of occurrence on joint dysfunction and disuse muscle atrophy in a rabbit model of extending knee joint contracture and its possible mechanism in part 1,the effects of ultrashort wave diathermy on joint dysfunction and disuse muscle atrophy in a rabbit model of extending knee joint contracture and its possible mechanism in part 2.Methods: In part 1,rabbits were randomly divided into control and immobilization groups.In the immobilization groups,the left knee joint of the rabbits were immobilized in extension for one,two,four,six,and eight weeks respectively.In part 2,the other rabbits which were immobilized in extension for eight weeks were also randomly divided into 6 groups.In the self-recovery groups(Group R),the rabbits were experienced one,two,and four weeks self-recovery respectively.In addition,the rabbits were experienced one,two,and four weeks ultrashort wave diathermy treatment respectively in ultrashort wave diathermy groups(Group T).After each period,the degree of total contracture,myogenic contracture,and arthrogenic contracture in each group were examined by the joint motion measuring instrument.In addition,skeletal muscle atrophy was used for the assessment of myogenic contracture,and it was analyzed by the cross-sectional area(CSA)of the rectus femoris.Furthermore,the expression of the protein levels for MyoD was examined by Western blot.Results: In part 1,with the joint fixation prolonged,the total contracture was progressed,and stabilized after the sixth week,but the myogenic contracture tended to be stable after the second week.The CSA of the rectus femoris was gradually decreased and stabilized after the fourth week.The expression of the protein levels for MyoD in the rectus femoris was gradually decreased and stabilized after the fourth week.In part 2,from the first week,the total contracture of both Group R and Group T were gradually decreased,and all the Group T were larger than Group R for the degree of declining at each time point(P<0.05).Furthermore,the result of myogenic contracture presented similarly with the result of total contracture.In addition,the arthrogenic contracture that in both of Group R and Group T were gradually decreased from the second week,but there was difference between Group R and Group T only at the fourth week(P<0.05).And from the first week,the CSA of the rectus femoris that in both of Group R and Group T were gradually increased,and all the Group T were larger than Group R for the degree of improving at each time point(P<0.05).From the second week,the expression of the protein levels for MyoD in the Group T were gradually increased,and it was stable at the first week.Moreover,the expression of the protein levels for MyoD in the Group R were continuously decreased at the first week,and it was gradually increased form the second week.Correspondingly,all the Group T were larger than Group R for the degree of improving at each time point.Conclusion:(1)During the immobilization of the rabbit model of extending knee joint contracture,joint dysfunction and disuse muscle atrophy occurred.This might be related to the decreased expression level of MyoD protein.(2)During the recovery of of the rabbit model of extending knee joint contracture,there were different degrees of recovery of joint dysfunction and disuse muscle atrophy.Compared with the groups of self-recovery,Ultrashort wave diathermy ameliorated joint dysfunction and skeletal muscle atrophy via upregulating the expression of MyoD protein in a rabbit model of extending knee joint contracture better.