PCL Bundles' Classification And The Mechanical And Histological Influence On The Lateral Tibial Plateau After PCL Ruptured

The posterior cruciate ligament (PCL) is a stable structure whose main role is controlling the posteodisplacement of tibial and regulating the rotation of tibial as well as the varus and valgus of knee joint partly. In this study, straining of PCL bundles is tested under different angle so as to investigate the biomechanical function of the PCL bundles and their internal correlation.Straining changes in several sites of the lateral tibial plateau by PCL injury is observed through biomechanics approach; histological changes of lateral tibial plateau cartilage and expression of MMP-13 and TIMP-1 in lateral tibial plateau cartilage are observed so as to investigate the function of MMP-13 and TIMP-1 in degeneration of lateral tibial plateau cartilage;It cound for us to provide theoretical evidence whether deficiency of PCL effects on the lateral tibial plateau.Chapter I The biomechanical study of PCL bundles' functional classificationOBJECTIVE To investigate the biomechanical function of the PCL bundles and their internal correlation and provide biomechanical evidence for the later experiments and clinical therapy.METHOD 12 fresh cadaveric knees from adult human beings were used. Selected the bilateral anterior part of the PCL tibial insertion and the bilateral posterior part of the PCL femoral insertion as the measure parts correspond to:anteromedial area fiber bundle (anteromedial bundle),anterolateral area fiber bundle (anterolateral bundle), posteromedial area bundle (posteromedial bundle) and posterolateral area bundle (posterolateral bundle). The strain on the PCL bundles was measured when the knees were applied with 1000N axial loading force in 0°,30°,60°and 90°positions. The bundles were functional classified by cluster analysis.RESULT 1.In 0°position, the strain on the posteromedial and posterolateral bundles was significantly larger than the anteromedial and anterolateral bundles (P<0.05), There were no significant diference between the anteromedial and anterolateral bundles (P>0.05) and so did the posteromedial and posterolateral bundles (P>0.05); In 30°,60°and 90°position, the strain on the anteromedial and anterolateral bundles was significantly larger than the posteromedial and posterolateral bundles (P<0.05), There were no significant difference between the posteromedial and posterolateral bundles (P>0.05) and so did the anteromedial and anterolateral bundles (P>0.05).2.The strain on the anterolateral and anteromedial bundles was increased by degrees when the knee flexed 0°,30°,60°and 90°, and all the difference were significant (P<0.05).3.Cluster analysis classfied the anteromedial bundle and the anterolateral bundle as one class and the posteromedial and posterolateral bundles as the other class. CONCLUSION 1.The anteromedial area and anterolateral area fiber bundles cound mainly maintain stability of the knee in flexed positions. 2.The posteromedial area and posterolateral area fiber bundles cound mainly maintain stability of the knee in extended positions. 3. Combined with the cluster analysis results, PCL may be classified into the anterolateral functional fiber bundle and the posteromedial functional fiber bundle.ChapterⅡThe Effect of PCL Rupture on the Biomechanics of Lateral Tibial PlateauOBJECTIVE To investigate the biomechanical influences of partial and total PCL rupture on the lateral tibial plateau.METHOD The straining of lateral tibial plateau anterior part, caudomedial part and posterior part in all fresh normal adult knee joint specimens including 12 specimens of complete PCL,6 of anterolateral bundle(ALB) rupture,6 of posteromedial bundle(PMB) rupture and 12 of complete rupture PCL are tested when the knee joints loaded 200N,400N,600N,800N and 1000N at 0°,30°,60°and 90°of flexion.RESULT 1.The straining of lateral tibial plateau anterior part, caudomedial part and posterior part shows no significant difference between PMB rupture group and PCL complete rupture group,complete PCL group and ALB 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,800N and 1000N at 0°of flexion,P<0.05; under the same load, the correlation of the absolute value of straining in every group of lateral tibial plateau. anterior part and caudomedial part increases in this way of PCL complete rupture group> PMB rupture group>ALB rupture group> complete PCL group,and of posterior part decreases in this way of PCL complete rupture group< PMB rupture group0.05; significant difference is showed among all the groups under the load of 600N,800N and 1000N at 30°of flexion,P< 0.05; under the same load,the correlation of the absolute value of straining in anterior part and caudomedial part increases in this way of PCL complete rupture group> ALB rupture group> PMB rupture group> complete PCL group, and of posterior part decreases in this way of PCL complete rupture group< ALB rupture group ALB rupture group> PMB rupture group> complete PCL group, there is significant difference among straining of all the groups of posterior part. Those of PCL complete rupture group and ALB rupture group are tebsile straining and PCL complete rupture group> ALB rupture group. Those of complete PCL group and PMB rupture group are compressive straining and complete PCL group> PMB rupture group.CONCLUSION 1.PCL complete rupture is likely to cause abnormal straining in all regions of lateral tibial plateau under different load and angle of flexion.2. Under the load of 200N and 400N, ALB rupture at 0°of flexion and PMB rupture at 30°of flexion cause no effect on the straining in all regions of lateral tibial plateau.3. Under the load of 600N,800N and 1000N, ALB rupture at 0°of flexion and PMB rupture at 30°of flexion cause apparently effect on the straining in all regions of the lateral tibial plateau.4. Abnormal straining in all regions of lateral tibial plateau can be caused by PCL complete rupture under different angle of flexion 5. Abnormal straining in all regions of the lateral tibial plateau can be caused by PMB rupture at 0°of flexion and ALB rupture at 30°,60°and 90°of flexion under different load.ChapterⅢThe Research of Histology about Degeneration of Lateral Tibial Plateau after Rupture of PCLOBJECTIVE Study the histological influence on lateral tibial plateau which was caused by rupture of PCLMETHOD Lateral tibial plateau of 48 rabbits matched mode pairs both in experiment side which PCL were transacted and control side, at the 4st,8rd,16th and 24th week,execute 12 rabbits randomly,then to observe lateral tibial plateau in general and through HE staining and immunohistochemistry staining,detect the expression of matrix metalloproteinase-13 (MMP-13)and Tisse inhibitor-1 of matrix metalloproteinasel (TIMP-1).RESULT 1.The observation in general showed that along with the increase of the time lateral tibial plateau of experiment group gradually abrasion, presenting isabeling, bad elasticity and formation of osteophytes.2.Along with the increase of the time the observation of histology shows fibering of lateral tibial plateau,meanwhile,there are abnormal cell disposition and increasingly clustered cell.3.expression of MMP-13 and TIMP-1 is higher in experimental group than that in control group,showing significant difference, P<0.05.4.In experimental group, expression of MMP-13 is increasing gradually at the 4rd,8st and 16th week,then decreasing at 24th week,showing significant difference, P< 0.05.5.In experimental group,expression of TIMP-1 is increasing gradually at the 4rd,8st and 16th week, then decreasing at 24th week, showing significant difference, P< 0.05.CONCLUSION 1. Rupture of PCL could cause the degeneration of the lateral tibial platea,As time go up.this condition will be aggravated.2.A regularity of expression of TIMP-1 and MMP13 is displayed that the expression is increasing in primal stage and decreasing in advanced stage after rupture of PCL,degeneration of the cartilage is speeding up because of unbalance between MMP-13 and TIMP-1.3.It is a important role for MMP-13 and TIMP-1 to participate in the course of degeneration of the lateral tibial plateau cartilage.