Related Experimental Studies Of ACL Reconstruction With Grafts

PartⅠExpression of TypeⅢCollagen and Biomechanical evaluation of Anterior Cruciate Ligament Reconstruction with Fresh-frozen Patellar tendon allograft and autograftObjective To observe the expression of type III collagen and biomechanical changes of anterior cruciate ligament reconstruction with fresh-frozen patellar tendon allograft and autograft in rabbits. Methods 42 skeletally matured New Zealand white rabbits were used in the experiment. 36 rabbits were removed two sides of ACL .One side was underwent ACL reconstruction with aseptically harvested fresh-frozen patellar tendon allograft, while the other side was reconstructed with patellar tendon autograft.The remained 6 rabbits were classified as control group.At the 3rd week, 6th week, 12th week after surgery,specimens were collected and processed for histological, immunohistochemical observation and the expression degree ofⅢprocollagen mRNA was detected using method of RT-PCR.The complex of femur-graft-tibia was biomechanical analysis.Results After implantation ,the autografts and allografts underwent a gradually heal process including cellular migration, collagen formation and remodeling. The negative expression of type III collagen were obseved in nomal ACL and fresh-frozen patellar tendon allografts and autografts.The amount of typeⅢprocollagen mRNA of patellar tendon autografts reached a maximum at 6 th weeks after the operation,while typeⅢprocollagen mRNA of fresh-frozen patellar tendon allografts at 12th weeks after the operation remain highly. Mechanical properties deteriorated obviously due to a process of the increase of type III collagen in the grafts. Mechanical properties of the grafts can not reach the lever of nomal.Conclusion The results suggested that the increase in type III collagen produced by cells of the extrinsic origin may be one of the mechanisms that induce mechanical deterioration of fresh-frozen allograft and autograft .The synthetized type III collagen were significant in allograft.A more thorough mechanism of changes in the graft matrix after cruciate ligament reconstruction is critical to the development of a successful means of enhancing remodeling after cruciate ligament reconstruction. PartⅡAngiogenic effect of allgraft freeze-dried achilles treated by Plasma rich in Platelet—released Growth Factors in ACL reconstruction at early stageObjective To observe angiogenic effect of allograft freeze-dried achilles treated by PRGF in ACL reconstruction at early stage.Methods 14 rabbits were used in the experiment .12 rabbits were removed two sides of ACL. Allograft freeze-dried achilles treated by PRGF was transplanted into one side knee to substitute the original ACL, while the other side only treated by saline as control. 2 rabbits were classified as sham group.The grafts were harvested 2nd,4th and 6th week from the 12 rabbits, respectively.The groups were compared on the basis of histologic and immunohistochemical staining method . MVD was measured by Weidner method, an indicator of revascularization.Results When compared with PRGF at the same time ,MVD of group PRGF were significant higher than that of group NS (p<0.01) . Moreover, PRGF promoted MVD of PRGF group was significantly greater than that of NS group. MVD of group NS and PRGF was 2.52±0.45,3.41±0.44,2.57±0.51 and 3.56±0.81,4.91±0.46,3.01±0.75 , respectively(p<0.01). The time of neovascular formation and the depth of vascular penetration into the grafts of the group PRGF are superior to those in the group of NS.Conclusion PRGF significantly promoted angiogenesis of the freeze-dried achilles in ACL reconstruction at early stage .PartⅢCollagen expression and biomechanical effect of allograft freeze-dried achillis treated by Plasma rich in Platelet—released Growth Factors in ACL reconstructionObjectiveTo observe the effect of the Achilles allograft treated with PGGF on the biomechanical and collagen expression on the reconstruction of Anterio rcruciate ligament(ACL) in rabbits . Methods 46 rabbits were used in the experiment .40 rabbits were removed two sides of ACL. Allograft freeze-dried achillis treated by PRGF was transplanted into one side knee to substitute the original ACL, while the other side only treated by normal saline as control. 6 rabbits were sham group.The grafts were harvested 3rd,6th,12th and 24 th weeks and compared on the basis of histologic ;The expression of Type III Collagen and TypeⅠCollagen were analysised by confocal laser scanning microscopy (CLSM).The complex of femur-graft-tibia was biomechanical analysis.Results Many inflammatory cells from recipien covered the surface of the graft at 3rd week after operation, however, the PRGF group was less than NS group. Cells gradually migrated into the deeper part of the graft in two groups. At 3 th week after operation, the proportion of Type III Collagen increased and TypeⅠCollagen decreasing in both groups.As the time passed, the proportion of Type III Collagen gradually increased between 3 th -12 th week after operation ,but compared with in PRGF group,the increasing of Type III Collagen is more significantly in NS group . At 12 th week after operation,TypeⅠCollagen gradually increased and Type III Collagen began to decrease.However, the decreasing of Type III Collagen and the increasing of TypeⅠCollagen in PRGF group was faster than that of in NS group. Mechanical properties of both group begin to increase following the decreasing of the proportion of Type III Collagen and the increasing of TypeⅠCollagen.The increasing of mechanical properties in PRGF group was more significantly than that of in NS group. At 24 th week after operation ,the mechanical properties in PRGF group was superior to that of in NS group . Conclusion The biomechanical and collagen remodeling of allograft freeze-dried achillis treated with PRGF could be promoted on the reconstruction of ACL .PartⅣHistology Study of Terylene Polyester Type LARS after reconstruction of anterior cruciate ligament in rabbitsObjective To study histology characteristics and ultrastructure of Terylene Polyester Type LARS artificial ligament after reconstruction of anterior cruciate ligament in rabbits. Methods 12 rabbits were removed one side of ACL. The Terylene Polyester Type LARS was transplanted to substitute the original ACL, and the transplanted Terylene Polyester Type LARS were covered with the remnant of ACL in 9 rabbits(A group), while only Terylene Polyester Type LARS were transplanted in 3 rabbits , which no covering with the remnant of ACL(B group).The grafts were harvested 1st ,3rd and 6th month and compared on the basis of histologic characteristics , and ultrastructural findings and compatibility.Results After 1 th months surgery , the grafts were covered with recipient connective tissues in group A ,but were not covered anything after 6 th months operation in group B; After 3 th months surgery there were irregularly aligned collagen fiber bundles slightly or in some portions, additionally, there was moderate to severe inflammatory cell reaction or foreign body reaction immediately adjacent to the LARS fibers in bone tunnel even in long-term specimens postsurgery. After 6 th months surgery , there were irregularly aligned collagen fiber bundles slightly or in some portions, collagen fiber couldn't parallel to stress. The tissue inside the LARS ligament as a whole showed no mature ligamentization and was not well functioning. Electron microscopy investigation showed the tissue near LARS fibers was highly cellular with a matrix of frequant, thin collagen fibrils. Among the collagen fiber bundles of the stroma were numerous osteoblasts and fibroblasts that were elongated, with large nuclei and an abundant, granular endoplasmic reculum. Light examination of these specimens revealed marked trabecular bone ingrowth into the periphery of the prosthesis and the incorporation of the LARS fibers into the bone matrix. Inflammatory cell reaction or foreign body reaction began to diminish.Conclusion The results suggest that Terylene Polyester Type LARS could be covered by recipient connective tissues.However, the recipient connective tissues was immaturity and could not develop into fiber parallel to stress. Terylene Polyester Type LARS was designed as a permanent replacement for the anterior cruciate ligament ,and used Terylene Polyester Type LARS in repairig and the reconstruction of cruciate ligament tissue ,however, may act as partly ,...