Study On The Functional Bundle Division Of ACL And The Effects Of Rupture ACL On The Medial Meniscus

The stable structure of knee joint is made up of anterior cruciate ligament(ACL),whose main role is controlling the antedisplacement of tibial and regulating part of rotation function.The role of medial meniscus is shocks absorption and stress transmission,partly restructuring the radial aversion of the joint.They influence each other in maintaining the stability of knee joint.With the development of MRI,arthroscope,early diagnosis and treatment of ACL injury turns to be easily achieved,meanwhile,it's found that the most frequent secondary injury of ACL occurs in meniscus medialis,the rate of incomplete rupture is higher than that of complete rupture.It is significant of reconstructing ACL,handling the complicating injury of medial meniscus and recovering the stability of knee joint so as to prevent the development of osteoarthrosis.At present,the presumption of the researching in the effect of ACL injury on meniscus medialis is the division of ACL fiber bundles, concentrates on the histological anatomy effect of ACL complete rupture on meniscus medialis,and on the biomechanics effect on posterior horn of meniscus medialis.The focal point of research lies in:1,the division of ACL fiber bundles based on appearance or function and how many does it divided in? according to what? 2,How is it the effect of incomplete rupture of ACL on the histological anatomy and biomechanics and its mechanism? 3,What degree of its effect on the other parts such as anterior horn and caudomedial part and what is its mechanism? The study and research is directly related to the early diagnosis and appraisement of ACL combining with medial meniscus injury.Therefore,more comprehension of the histological effect and biomechanics effect of ACL rupture on medial meniscus is of great value and meaning on prevention and cure of medial meniscus injury and osteoarthrosis caused by ACL rupture.ACL rupture affects medial meniscus mainly in the aspects of morphology,vitodynamics and histology,moreover,in the displacement of medial meniscus.This research intends to observe the morphology change of ACL bundles in the motion of knee joint in the presumption of dividing the bundles based on function by determining the vitodynamics of ACL fiber bundles and using clustering statistical method;to observe the ultrastructural change of medial meniscus,the expression of IL-1βand MMP13 and the degree of semiluxation after the rupture of ACL by the medium of histology;To approach the mechanism of displacement and the degree of effect on displacement made by ACL so as to provide theoretical evident for early clinical diagnosis and cure.ChapterⅠStuday on the Functional Anatomy of the ACLObjective To investigate the functional anatomy of the anterior cruciate ligament(ACL)and to provide functional anatomic evidence about the histological and biomechanical effect on the medial meniscus after ACL injury.Method The specimens in this experiment are 6 normal knee joints of adult male.First,observing the gross shape and form of the ACL and medial meniscus.Then,measuring the transverse diameter and vertical diameter of the insertions of ACL on tibia and femur and measuring the length of the anteromedial part of ACL and the posterolateral part when the knee joint located at 0°,30°,60°,90°respectively.Calculating the included angle between anteromedial part of ACL and the femoral Blumensatt line and the included angle between posterolateral part of ACL and the line which connects the anterior horn and posterior horn of medial meniscus by Photoshop software.Last,calculating the area of the insertions of ACL using Photoshop software and other selective area calculated software.Results 1.Morphological result:The area of ACL insertion on tibia is bigger than that on femur.The inner fibers connect interlacedly and hard to be separated.The anterior horn of medial meniscus is thinner than posterior horn.The central part of meniscus is concave,while circumferentia is convex.2.Area calculated result:The area,transverse diameter and vertical diameter of ACL insertion on tibia are bigger than those counterparts on femur,the difference are of significance(p＜0.05).3. Length calculated result:①The length of the anteromedial part of ACL is longer than the posterolateral part no matter the knee at what location (p＜0.05).②The length of the anteromedial part of ACL at different locations can be ordered as 90°,0°,30°,60°from maximum to minimum. The difference of length of any two locations is of significance(p＜0.05). The maximum length of posterolateral part of ACL appears at the location of 0°and the minimum length of poasterolateral part occurs at the location of 90°(p＜0.05),the moderate lengths at the location of 30°and 60°have no significant difference(p＞0.05).4.Angle calculated result:When the knee locates at 0°and 30°,the included angle of ACL and medial meniscus is bigger than the included angle of ACL and femur(p＜0.05).When the knee locates at 60°and 90°,the included angle of ACL and medial meniscus is smaller than the included angle of ACL and femur(p＜0.05).The included angle of ACL and medial meniscus are ordered from big to small with the sequence as 0°,30°,60°,90°.The included angle of ACL and femur are ordered as 90°,60°,30°and 0°.The angle at 0°and 30°are have no significant difference(p＞0.05).Conclusion The inner fibers of ACL connect inteflacedly and hard to separated anatomically.The posterolateral part of ACL are relatively longer when the knee at 0°and the angle are bigger than the anteromedial angle when the knee at 0°and 30°.The appearance suggest the posterolateral part of ACL play its role when the knee locates at straighten position.And the anteromedial part of ACL are longer at the position of 90°with the angle bigger at 60°and 90°,which together suggest that the anteromedial one exert its role when the knee flex.The above suggestions with the fact that the area of ACL insertion on tibia bigger than that on femur encourage a further research about the functional bundle division of ACL.ChapterⅡStudy on the Functional Bundle Division of the ACLObjective To investigate the functional bundle division of the ACL.Method The specimens in this experiment are 6 normal knee joints of adult male.Choosing the bilateral areas in front of the ACL tibial insertion and the bilateral areas at the back of the ACL femoral insertion as the four straingauge point.They are corresponding to anteromedial bundle, anterolateral bundle,posteromedial bundle and posterolateral bundle respectively.Testing and measuring the strain of each four bundle under the load of 800N with the knee joint locate from 0°to 90°and then using the cluster analysis to functional division the anterior cruciate ligament. Results 1.①When the knee locate at 0°,the strain of ACL anterolateral bundle and posterolateral bundle are bigger than anteromedial and posteromedial bundle(p＜0.05).However,the difference between anterolateral bundle and posterolateral bundle and that between anteromedial and posteromedial bundle are of no significance (p＞0.05).②When the knee locate at both 30°and 90°,the strain of ACL anteromedial bundle and posteromedial bundle are bigger than anterolateral and posterolateral bundle(p＜0.05).However,the difference between anterolateral bundle and posterolateral bundle and that between anteromedial and posteromedial bundle are of no significance(p＞0.05).③When the knee locate at 60°,the strain of each bundle are ordered from maximum to minimum as follows:posteromedial bundle, anteromedial bundle,posterolateral bundle and anterolateral bundle.The differences between each bundles are of significance(p＜0.05).2.①The strain of the anteromedial bundle coincide with the strain of the posteromedial bundle.The strain of these two bundles at different knee positions are ordered from maximum to minimum as the sequence of 90°, 60°,30°,0°.The differences between each two position are of significance (p＜0.05).②The strain of the anterolateral bundle at each position are of no significance(p＞0.05).③The strain of the posterolateral bundle reaches its peak at the position of 60°(p＜0.05),and reaches its bottom at the position of 30°(p＜0.05).The strain of 0°and 90°are moderate and have no significant difference(p＞0.05).3.Cluster analysis:The anteromedial bundle and the posteromedial bundle can be regared as the same kind of bunch from the view of cluster analysis.And so do the anterolateral bundle and the posterolateral bundle.Conclusion 1.When the knee at the position of 0°,the strain of the anterolateral bundle and the posterolateral bundle are bigger than the medial ones.However,when the knee at the other bended positions,the strain of the anteromedial bundle and the posteromedial bundle are bigger the lateral ones.So,we draw a conclusion that the lateral bundles maintain the stability mainly when the knee straighten and the medial ones mainly keep the stable when the knee flex.Combined with the cluster analysis,the ACL can be regarded as two functional bundles:the anteromedial bundle and the posterolateral bundle. mode pairs both in experiment side and control side.In the 1 st,3rd,6th and 8th week,execute 12 rabbits randomly,then observe medial meniscus in general,measure medial displacement index(MDI),observe through HE staining,and immunohistochemistry staining,detect the expression of IL-1β,MMP13.Results 1.the observation in general showed that along with the increase of the time medial meniscus of experiment group gradually.wore, even ruptured presenting yellow and bad elasticity.2.MDI of experiment group apparently exceeded control group(p＜0.05),showing significant difference.3.along with the increase of the time the observation of histology showed uneven surface of meniscus,loose tissue,disorder of collagen fibers,infiltration of inflammatory cell,interstitial edema, deformation of intracytoplasm mitochondrion in the chondrocytes.4.In the 1st,3rd,6th and 8th week,expression of IL-1βand MMP1.3 was higher in experiment group than that in control group,showing significant diffenrence(p＜0.05).5.in experiment group expression of IL-1βwas lower in the 1st week than that in the 3rd,6th and 8th week,showing significant diffenrence(p＜0.05);expression was higher in the 3rd and 6th week than that in the 8th week,showing significant diffenrence(p＜0.05); but there was no significant difference between the 3rd and 6th week (p＞0.05).6.in experiment group expression of MMP13 was lower in the 1st week than that in the 3rd and 6th week,showing significant diffenrence (p＜0.05);expression was higher in the 6^thweek than that in the 8^thweek, showing significant diffenrence(p＜0.05);but there was no significant difference between the 3^rdand the 6^thor 8^thweek,also between the 1^stand the 8^th week(p＞0.05).Conclusion Rupture of ACL could cause the degeneration of medial meniscus.After rupture of ACL the increase of MDI hinted that rupture of ACL could cause secondary semiluxation of medial meniscus. Increased expression of IL-1β,MMP13 hinted they might be a factor of degenaration of medial meniscus.ChapterⅣThe Effect of ACL Rupture on the Biomechanics of Medial MeniscusObjective To investigate the effect of the ACL rupture on the biomechanics of the medial meniscus and therefore to provide the theory guidance about early diagnosis and treatment of medial meniscus injury which occur after the ACL rupture.Method The specimens in this experiment are 6 normal fresh knee joints of adult male.At first,all the 6 specimens,whose medical meniscus straining were measured at different angles(0°,30°,60°and 90°) under different loads(200N,400N,600N and 800N),were regarded as the group with intact ACL.Then,3 specimens were randomly treated as the group with the anteromedial part of ACL ruptured.The other 3 knees were treated as the group whose posterolateral part of-ACL ruptured. Measuring the straining of medical meniscus of the two groups as step one. At last,cutting off the ACL completely in all 6 specimens as the group with the ACL completely ruptured and doing the measurement at the four angles under the four loads similarly.According to the hooke's law,take the result under unit 200N of test to carry on the statistical analysis.Results 1.results of the intact ACL group:①0°position:the strain in anterior horn and caudomedial part are bigger than posterior horn (p＜0.05).But the strain in anterior horn and caudomedial part have no significant difference.②30°position:the strain order from maximum to minimum at this position are as follows:caudomedial part,anterior horn and posterior horn(p＜0.05).③60°position:the difference of the strain in caudomedial part and posterior horn are of no significance (p＞0.05).④90°position:the strain in posterior horn are bigger than that in caudomedial part(p＜0.05).2.The comparison of the AMB ruptured group with the intact group:①0°position:all the strains in anterior horn,caudomedial part and posterior horn have no significant difference. (p＞0.05).②30°position:all the strains in anterior horn,caudomedial part and posterior horn have no significant difference.(p＞0.05).③60° position:the difference of the strain in anterior horn between the two group are of no significance(p＞0.05),while the strain of caudomedial part and posterior horn in AMB ruptured group are bigger than that of the intact group(p＜0.05).④90°position:all the strains in anterior horn, caudomedial part and posterior horn have no significant difference. (p＞0.05).3.The comparison of the PLB ruptured group with the intact group:①0°position:the strain in anterior horn,caudomedial part and posterior horn of PLB ruptured group are bigger than strain in the intact group(p＜0.05).②30°position:the strain in posterior horn of PLB ruptured group are bigger than strain in the intact group,while the strain in the other two part are no significant difference.③60°position:only the strain in caudomedial part of PLB ruptured group are bigger than strain in the intact group,while the strain in the other two part are no significant difference.④90°position:all the strains in anterior horn, caudomedial part and posterior horn have no significant difference in two groups.(p＞0.05).4.The comparison of the complete ruptured group with the intact group:①not only at the 0°position,but also at the position of 60°and 90°,the strain in anterior horn,caudomedial part and posterior horn of complete ruptured group are bigger than strain in the intact group (p＜0.05).②30°position:the strain in posterior horn of complete ruptured group are bigger than strain in the intact group at this position, while the strain in the other two part are no significant difference (p＞0.05).5.The comparisons among the complete ruptured group,the AMB ruptured group and the PLB ruptured group:①0°position:in the anterior horn and the caudomedial part,the strain of the complete ruptured group and the PLB ruptured group are bigger than the AMB ruptured group(p＜0.05),while the strain of the complete ruptured group and the PLB ruptured group at these two parts are no significant difference(p＞0.05).And the strain at the posterior horn are ordered from big to small as the complete group,the PLB group and the AMB group.②30°position:the strain at the anterior horn have no significant difference among three groups(p＞0.05).When it comes to the strain at the caudomedial part,the complete ones are bigger than the other two groups(p＜0.05).And the strain at posterior horn of the AMB group are smaller than the other two.③60°position:the strain in anterior horn and caudomedial part of the complete group are bigger than the AMB group and the PLB group(p＜0.05).While the strain in posterior horn of the complete group is only bigger than the PLB group,the strain of AMB group is close to the complete ones.Moreover,except the anterior horn, the AMB group are superior in strain to the PLB group at the caudomedial part and the posterior horn.④90°position:at any part of the medial meniscus,the complete ruptured group is bigger than the other two(p＜0.05).The AMB group and the PLB group have no significant difference in strain(p＞0.05). Conclusions 1.When ACL complete ruptured,the posterior horn is influenced apparently at any position.The anterior horn and caudomedial part are affected at the 0°,60°and 90°.This achievement may be used as the theoretical evidence to support the early reparation of the ACL comPlete rupture.2.The rupture of the anteromedial part of the ACL can cause the biomechanical influence on caudomedial part and posterior horn of the medial meniscus when the knee flex.And the rupture of the posterolateral part of ACL also arouse the biomechanical disorder at the anterior horn,posterior horn and caudomedial part of medial meniscus, which need to be further explored.ChapterⅤThe Effect of ACL Rupture on the Circumferential Displacement of Medial MeniscusObjective To investigate the effect of ACL rupture on medial meniscus circumferentia displacement and the correlation between the rupture and medial meniscus displacement.Method The specimens in this experiment are 6 normal fresh knee joints of adult male.At first,all the 6 specimens,whose medical meniscus displacement were measured at different angles(0°,30°,60°and 90°) under different loads(200N,400N,600N and 800N),were regarded as the group with intact ACL.Then,3 specimens were randomly treated as the group with the anteromedial part of ACL ruptured.The other 3 knees were treated as the group whose posterolateral part of ACL ruptured. Measuring the circumferentia displacement of medical meniscus of the two groups as step one.At last,cutting off the ACL completely in all 6 specimens as the group with the ACL completely ruptured and doing the measurement at the four angles under the four loads similarly.Results 1.The circumferentia displacement of medial meniscus:the displacement of the intact ACL group are ranged from 1.0mm to 1.5mm; the results of AMB ruptured group are in the scale of 2.0mm to 3.0mm;the displacement of PLB ruptured group are distributed between 2.0mm and 3.2mm and the complete ruptured group have the results range from 3.1mm to 4.9mm.2.The circumferentia displacement of medial meniscus at different locations:①0°position:While the loads become heavier,the displacements in all groups become larger accordingly,showing a linear relationship roughly.The displacement of the complete ruptured group are the largest among the four groups(p＜0.05).The results of the PLB ruptured group are larger than that of the intact group at this position under every load(p＜0.05).The PLB ruptured group are larger than the AMB rupture ones only when the load is 800N(p＜0.05).And AMB group are larger than the intact group only under the load of 600N(p＜0.05).②30° position:only the intact ACL group and the AMB ruptured group show a positive linear relationship with the load at this position.While the complete ruptured group's displacement are still the largest ones among the four groups(p＜0.05),the displacements of the intact group are the smallest ones(p＜0.05).The displacements between the AMB ruptured group and the PLB ruptured group have no significant difference in statistics(p＞0.05).③60°position:all the groups except the PLB ruptured group are vary in accordance with the load.The heavier the load,the larger the displacement.The complete ruptured ones are larger than the intact ones at any load at 60°position,while they are lager than the other two groups under the load of 400N,600N and 800N(p＜0.05).Only under 400N load,the PLB ruptured group is larger than the AMB ruptured group. And both the PLB ruptured and the AMB ruptured are larger than the intact group under any load(p＜0.05).④90°position:all the groups are showing a positive linear relationship with the increasing load.The maximum displacement occur in the complete ruptured group while the minimum displacement occur in the intact group(p＜0.05).And at this position,the results of the AMB ruptured group are larger than the PLB ruptured group under the load of 400N(p＜0.05).Conclusions While ACL is intact,the displacement of the medial meniscus range from 1.0mm to 1.5mm,which may be the physical displacement.The fact that displacement of medial meniscus abnormally increase at 30°after the AMB ruptured suggest AMB play an important role in maintaining the stability of medial meniscus while knee flex.And PLB are proved to be important in maintaining the stability of medial meniscus when knee are straighten.After the ACL completely cut off,the medial meniscus become unstable at any position.All the above may draw a conclusion that early reestablishment of the ACL help to maintain the stability of knee after ACL injury.