| Posterior cruciate ligament(PCL) is the primary structure restraint to posterior tibial translation. In the PCL-deficient knee, balance of kinematics is damaged. The strains on other structures increase to maintain knee joint stability. Medial collateral ligament is the most important static structure of medial stability, restricting against valgus and tibial external rotation, as well as the most important structure resisting to posterior tibial translation in PCL-deficient knee. PCL-deficient knees showed that after many years almost patients had articular cartilage damage, even osteoarthritis(OA). Few reports focused on the alteration of ligaments in PCL-deficient knees. In this study, straining changes in several sites of MCL caused by PCL injury is observed in biomechanics approach through the arc of flexion from0°to90°with different axis loads; mechanical methods in micro and macro levels to observate the rabbit knee joint at different time points after PCL injury, including:maximum load, maximum displacement, elastic modulus and micro-hardness; histological histological methods in rabbits MCL knee injury PCL to study morphological change, Ⅰ and Ⅲ collagen alteration, so as to provide theoretical evidence whether deficiency of PCL effects on the MCL Chapter I The Effect of PCL Rupture on the Biomechanics of MCLOBJECTIVE:The effect of PCL injury in several sites of MCL by measuring biomechanics is observed so as to explore the mechanism of MCL injury after PCL ruptures.METHOD:The straining of MCL femoral attachment, midpoint and tibial attachment in all fresh normal adult knee joint specimens including12specimens of complete PCL,6of anterolateral bundle(ALB) rupture,6of posteromedial bundle(PMB) rupture and12of complete rupture PCL are tested when the knee joints loaded with200N,400N,600N,800N through the arc of flexion from0°,30°,60°to90°.RESULT:1.0°position:under200N,400N,600N and800N load, after PMB、ALB or PCL ruptured the straining on the femoral attachment, midpoint and tibial attachment of sMCL did not increase significantly(P>0.05).2.30°position:under200N load, after PMB. ALB or PCL ruptured the strains on the femoral attachment, midpoint and tibial attachment of sMCL did not increase significantly(P>0.05); Under the load of400N,600N and the800N, the stains of sMCL increase significantly(P<0.05); The strains between PMB rupturing and ALB rupturing under various loads were not difference significantly(P>0.05).3.60°position:Under200N load, after PMB、ALB or PCL ruptured the strains on the femoral attachment, midpoint and tibial attachment of sMCL did not increase significantly(P>0.05); Under the load of400N, 600N and the800N, the stains of sMCL increase significantly(P<0.05); Under serious loads, after PCL, ALB ruptured the stains of sMCL increase significantly(P<0.05); The strains of PCL deficient knee were much lager than the PMB or ALB(P<0.05).4.90°position:Under200N load, after PMB ruptured, the strains of femoral attachment and midpoint were not significantly increased(P>0.05), while the tibial attachment of the strains were significantly increased(P<0.05); As well as under400N,600N and800N load, the strains between ALB and PCL deficience, PMB and PCL deficience were different significantly(P<0.05).5.200N load:In0°and30°position, after PMB、ALB or PCL ruptured the straining on the femoral attachment, midpoint and tibial attachment of sMCL did not increase significantly(P>0.05); In60°position, the strains of ALB deficient and PCL deficient knee all much more than normal and PMB deficient knee(P<0.05); In90°position, after PMB、ALB or PCL ruptured the straining on the femoral attachment, midpoint and tibial attachment of sMCL increased significantly(P<0.05).6.400N load:In0°position, after PMB、ALB or PCL ruptured the straining on the femoral attachment, midpoint and tibial attachment of sMCL did not increase significantly(P>0.05); In30°and60°position, the strains of PMB deficient、ALB deficient and PCL deficient knee all much more than normal knee(P<0.05); In60°position, the strains of PMB deficient、ALB deficient and PCL deficient knee were much different(P<0.05);In90°position, after PMB、ALB or PCL ruptured the straining on the femoral attachment, midpoint and tibial attachment of sMCL increased significantly(P<0.05).7.600N load:In0°position, after PMB、ALB or PCL ruptured the straining on the femoral attachment, midpoint and tibial attachment of sMCL did not increase significantly(P>0.05); In30°and60°position, the strains of PMB deficient、ALB deficient and PCL deficient knee all much more than normal knee(P<0.05); In30°position, the strains of PMB deficient、ALB deficient and PCL deficient knee were not different(P>0.05); In60°position, the strains of PMB deficient、ALB deficient and PCL deficient knee were much different(P<0.05);In90°position, after PMB、ALB or PCL ruptured the straining on the femoral attachment, midpoint and tibial attachment of sMCL increased significantly(P<0.05).8.800N load:In0°position, after PMB、ALB or PCL ruptured the straining on the femoral attachment, midpoint and tibial attachment of sMCL did not increase significantly(P>0.05); In30°and60°position, the strains of PMB deficient、ALB deficient and PCL deficient knee all much more than normal knee(P<0.05); In30°position, the strains of PMB deficient、ALB deficient and PCL deficient knee were not different(P>0.05); In60°position, the strains of PMB deficient、ALB deficient and PCL deficient knee were much different(P<0.05);In90°position, after PMB、ALB or PCL ruptured the straining on the femoral attachment, midpoint and tibial attachment of sMCL increased significantly(P<0.05).CONCLUSION:1.PCL injury effects biomechanics of MCL2.PMB and ALB collaborate and compose of the whole function of PCL Chapter Ⅱ The Effect of PCL Rupture on the Material Biomechanics of MCLOBJECTIVE:Study the material biomechanics alteration on MCL which was caused by rupture of PCLMETHOD:MCL of48rabbits matched mode pairs both in experiment side which PCL were transacted and control side, at the8th,16th,24th and40th week, executed12rabbits randomly, then to observe material biomechanics of MCL, including:maximum load, maximum displacement, elastic modulus and micro-hardness.RESULT:1. In different periods, no much difference was detected between experimental and control groups in MCL anatomy.2.In different periods, no significant difference was detected between experimental and control groups in MCL length, maximum displacement(P>0.05).3. At the8th,16th and24th week, MCL maximum load of the test group did not increased significantly(P>0.05); However, at40th week, MCL maximum load of the test group decreased significantly(P<0.05).4. At the8thand16th week, MCL elastic modulus difference between the test group and control group was no significant(P>0.05); At24th week, elastic modulus of the test group is much more than the control group (P<0.05). At the40th week, elastic modulus of the test group is much fewer than the control group(P<0.05).5.At the8th and16th week, hardness of MCL of test group was no increased significantly(P>0.05); At24th week, hardness of the test group is more than the control group sinificantly(P<0.05); At the40th week, hardness of the test group is much fewer than the control group (P<0.05).CONCLUSION:1. In short-term knee injury has no significant effect on mechanical properties of rabbits MCL under the physiological load, but with time, the mechanical properties decreased significantly.2. Nanoindentation can be used for biomechanical study of ligament. OBJECTIVE:To explore the histologic effect of PCL rupture on the MCL.METHOD:MCL of48rabbits matched mode pairs both in experiment side which PCL were transacted and control side, at the8th,16th,24th and40th week, executed12rabbits randomly, then to observe histologic alteration of MCL, through HE staining and picrosirius-polarization method.RESULT:1. Histological section:At the8th,16th and24th week, there was little difference between experimental group and control group; At40th week, the collagen in experimental group was much thinner than control group.2.At the16th and24th week, type Ⅰ collagen in MCL of the test group is much more than the control group(P<0.05); However, at 40th week, type Ⅰ collagen in MCL of the test group decreased significantly(P<0.05).3.At the16th and24th week, type Ⅲ collagen in MCL of the test group is much more than the control group(P<0.05); However, at8th,16th and40th week, type Ⅲ collagen in MCL of the test group is not much different with control group(P>0.05).4. At the8th,16th and24th week, total amount of type Ⅰ and type Ⅲ collagen in MCL of the test group is much more than the control group(P<0.05); However, at40th week, total amount of collagen in MCL of the test group is much fewer than control group(P<0.05).5. At the8th week, ratio of type Ⅰ/Ⅲ collagen in MCL of the test group is not much different with control group(P>0.05); However, at16th,24th and40th week, ratio of type Ⅱ/Ⅲ collagen in MCL of the test group is much fewer than control group(P<0.05).CONCLUSION:In short-term knee injury has no significant effect on histological properties of rabbits MCL under the physiological load, but with time, the histological properties decreased significantly. |
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