Study On The Biomechanical And Histological Effects Of Rupture ACL On The Lateral Meniscus

The anterior cruciate ligament(ACL) is a stable structure whose main role is controlling the antedisplacement of tibial and regulating the rotation of tibial as well as the varus and valgus of knee joint partly.The role of the lateral meniscus which is an important ingredient of the knee is shock absorption and stress transmission and stabilization of the knee joint.With the development of MRI and arthroscope,early diagnosis and treatment of ACL injury turns to be easily achieved,meanwhile,it is found that the secondary injury of ACL deficiency always occurs in articular cartilage,but it is little known whether deficiency of ACL effects on the lateral meniscus.In this study,straining changes in several sites of lateral meniscus caused by ACL injury is observed through biomechanics approach;histological changes of meniscus and expression of IL-1βand MMP13 in meniscus are observed so as to investigate the function of IL-1βand MMP13 in degeneration of lateral meniscus;circumferentia displacement of lateral meniscus after ACL injury is measured,so as to provide theoretical evidence whether deficiency of ACL effects on the lateral meniscus. ChapterⅠThe Effect of ACL Rupture on the Biomechanics of Lateral MeniscusOBJECTIVE The effect of ACL injury on all locations of lateral meniscus by measuring biomechanics is observed so as to explore the mechanism of lateral meniscus injury after ACL rupture.METHOD The straining of lateral meniscus anterior horn, caudomedial part and posterior horn in all fresh normal adult knee joint specimens including 10 specimens of complete ACL,5 of anteriomedialis bundle(AMB) rupture,5 of post-lateral bundle rupture and 10 of complete rupture ACL are tested when the knee joints loaded 200N,400N,600N and 800N at 0°,30°,60°and 90°of flexion.RESULT 1.The straining of lateral meniscus anterior horn, caudomedial part and posterior horn shows no significant difference between PLB rupture group and ACL complete rupture group,complete ACL group and AMB rupture group under the load of 200N and 400N at 0°of flexion,P＞0.05;significant difference is showed among all the groups under the loads of 600N and 800N at 0°of flexion,P＜0.05; under the same load and angle of flexion,the correlation of the absolute value of straining in every group of lateral meniscus anterior horn and caudomedial part increases in this way of ACL complete rupture group＞PLB rupture group＞AMB rupture group＞complete ACL group,and of posterior horn increases in this way of ACL complete rupture group＜PLB rupture group＜AMB rupture group＜complete ACL group. 2.The straining of lateral meniscus anterior horn,caudomedial part and posterior horn shows no significant difference between AMB rupture group and ACL complete rupture group,complete ACL group and PLB rupture group under the loads of 200N and 400N at 30°of flexion,P＞0.05;significant difference is showed among all the groups under the load of 600N and 800N at 30°of flexion,P＜0.05;under the same load and angle of flexion,the correlation of the absolute value of straining in every group increases in this way of ACL complete rupture group＞AMB rupture group＞PLB rupture group＞complete ACL group.3.There is significant difference among all the groups under the load of 200N,400N,600N and 800N at 60°and 90°of flexion,P＜0.05.under the same load and angle of flexion,the correlation of the absolute value of straining in every group increases in this way of ACL complete rupture group＞AMB rupture group＞PLB rupture group＞complete ACL group.CONCLUSION 1.ACL complete rupture is likely to cause abnormal straining in all regions of lateral meniscus under different load and angle of flexion.2.Under the load of 200N and 400N,AMB rupture at 0°of flexion and PLB rupture at 30°of flexion cause no effect on the straining in all regions of lateral meniscus.3.Under the load of 600N and 800N,AMB rupture at 0°of flexion and PLB rupture at 30°,60°and 90°of flexion cause apparently effect on the straining in all regions of lateral meniscus.4.Abnormal straining in all regions of lateral meniscus can be caused by PLB rupture at 0°of flexion and AMB rupture at 30°,60°and 90°of flexion under different load.ChapterⅡThe Research of Histology about Degeneration of Lateral Meniscus after Rupture of ACLOBJECTIVE Study the effect on lateral meniscus which was caused by rupture of ACL.METHOD Lateral meniscus of 48 rabbits matched mode pairs both in experiment side which ACL were transacted and control side,at the 1^st,3^rd,6^th and 8^th week,execute 12 rabbits randomly,then to observe lateral meniscus in general and through HE staining and immunohistochemistry staining,detect the expression of IL-1βand MMP13.RESULT 1.The observation in general showed that along with the increase of the time lateral meniscus of experiment group gradually wore,even ruptured,presenting yellow and bad elasticity.2.Along with the increase of the time the observation of histology shows uneven surface of meniscus,loose tissue,disorder of collagen fibers,infiltration of inflammatory cell,interstitial edema and deformation of intracytoplasm mitochondrion in the chondrocytes.Histological evaluation of the degeneration in fibrocartilage of meniscus in both groups:The scores at the 1^st,3^rd,6^th and 8^th week were higher in the experimental group than those in the control group,showing significant difference,P＜0.05; the scores of experimental group at the 6^th and 8^th week was higher than that at the 1^st and 3^rd week,showing significant difference,P＜0.05,but there is no significant difference between the 1^st and 3^rd week,P＞0.05.3.At the 1^st,3^rd,6^thand 9^th week,expression of IL-1βand MMP13 is higher in experimental group than that in control group,showing significant difference,P＜0.05.4.In experimental group,expression of IL-1βis higher at the 3^rd than that at 1^st and 8^th week,showing significant difference,P＜0.05,expression of IL-1βis higher at the 6^th week than that at 1^st and 8^th week,showing significant difference,P＜0.05,expression of IL-1βis higher at the 8^th week than that at 1^st week,showing significant difference,P＜0.05,but there is no significant difference between the 3^rd and 6^th week.5.In experimental group, expression of MMP13 is higher at the 3^rd week than that at 1^st and 8^th week,showing significant difference,P＜0.05,expression of MMP13 is higher at the 6^th week than that at 1^st and 8th week,showing significant difference,P＜0.05,expression of MMP13 is higher at the 8^th week than that at 1^st week,showing significant difference,P＜0.05,but there is no significant difference between the 3^rd and 6^thweek,P＞0.05.CONCLUSION 1.Rupture of ACL could cause the degeneration of lateral meniscus.2.A regularity of expression of IL-1βand MMP13 is displayed that the expression is increasing in primal stage and decreasing in advanced stage after rupture of ACL 3.The high expression of IL-1βand MMP13 hints that IL-1βand MMP13 maybe a promotional factor which causes the degeneration of lateral meniscus.4.The histological evaluation criterion of degeneration of meniscus was made first time.ChapterⅢThe Effect of ACL Rupture on the Circumferential Displacement of Lateral MeniscusOBJECTIVE To explore the effect of ACL rupture on lateral meniscus circumferentia displacement and the correlation between the degree of ACL rupture and circumferentia displacement.METHOD The circumferentia displacement of lateral meniscus in all fresh normal adult knee joint specimens including 10 specimens of complete ACL,5 of anteriomedialis bundle(AMB) rupture,5 of post-lateral bundle rupture(PLB) and 10 of complete rupture ACL are tested when the knee joints loaded 200N,400N,600Nand 800N at 0°, 30°,60°and 90°of flexion. RESULT 1.The limit of circumferentia displacement of lateral meniscus is distributed between 0.5～2.7mm in complete ACL group.2. At 0°of flexion and under the loads of 200N,400N and 600N,the circumferentia displacement of lateral meniscus between ACL complete rupture group and PLB rupture group,complete ACL group and AMB rupture group shows no significant difference,P＞0.05;significant difference is displayed between complete ACL group and PLB rupture group,ACL complete rupture group and complete ACL group,AMB rupture group and PLB rupture group,P＜0.05;there is significant difference among each group under the load of 800N at 0°of flexion,P＜0.05.3.Under the loads of 200N and 400N,the circumferentia displacement of lateral meniscus between complete ACL group and PLB rupture group,ACL complete rupture group and AMB rupture group shows no significant difference at 30°and 60°of flexion,P＞0.05,and that among the other groups shows significant difference,P＜0.05;Under the loads of 600N and 800N,the circumferentia displacement among every group shows significant difference at 30°and 60°of flexion,P＜0.05.4.Under the loads of 200N,the circumferentia displacement of lateral meniscus between complete ACL group and PLB rupture group, ACL complete rupture group and AMB rupture group shows no significant difference at 90°of flexion,P＞0.05,and that among the other groups shows significant difference,P＜0.05;Under the loads of 200N,600N and 800N,the circumferentia displacement among every group shows significant difference at 90°of flexion,P＜0.05.CONCLUSION 1.The physiological circumferentia displacement of lateral meniscus is between 0.5mm and 2.7mm.2.The circumferentia displacement of lateral meniscus in AMB rupture group at flexed position of the knee joint becomes bigger than that in complete ACL group.3.The circumferentia displacement of lateral meniscus in PLB rupture group at straight position of the knee joint becomes bigger than that in complete ACL group.4.The circumferentia displacement of lateral meniscus becomes big at all position of the knee joint when the ACL is ruptured completely.5.The abnormal circumferentia displacement of lateral meniscus after ACL rupture hints that ACL rupture maybe a factor which causes the degeneration of lateral meniscus.