Histological Studies Of Intra-articular Healing Inanterior Cruciate Ligament Reconstruction With Auto-allo-graft

Objective:Anterior cruciate ligament(ACL) rupture is one of the most common injuries in sports medicine trauma.Such injuries lead to joint instability and increased risk for degenerative joint disease later in life.Serious consequences after anterior cruciate ligament rupture,easy to cause serious knee stability decreased,and also easy to cause the meniscus within the knee joint and cartilage damage,the patient’s normal life and movement brought serious influence.so,in the field of sports trauma,anterior cruciate ligament rupture has been the hotspot and difficulty in the field of research. To investigate the histological change of healing of autologous allogeneic mixed tendon, Provide histology theoretical of autologous-allogeneic mixed tendon application in clinical practice.Methods: ACL reconstruetion materials harvested from New Zealand rabbits’ bilateral tendons of extensori digitorum longus.Grafts are packed in two layers of sterilitas Plastic bag,then which were slowly frozen to-80℃ and kept 14 days;The tendons graft were kept at- 20 ℃.Fourty newzealand rabbits are equally divided into auto-allo-graft groupa and llograft group,each group are twenty.After transecting the ACL, tibial and femoral bone tunnels were created to implant each graft in the native ACL position.After 3,8,12 and 24 weeks,gross observations, and histological evaluations of the repaired knees were performed.Results:At 3 weeks postoperatively.Each group showed inflammatory cells infiltrated and intraarticular graft necrosis.At 8 weeks postoperatively,more fibroblasts infiltrated into the allografts and auto-allo-graft,Collagen fibers arranged disorderly.Auto-allo-graft had a higher overall cellularity than allografts.At 12 weeks postoperatively,most part of the auto-allo-graft had been replaced by the new ingrown tissue,regular direction fibers showed up,allografts collagen fibers arranged still disorderly,tendon center showed cell free area.At 24 weeks postoperatively, auto-allo-graft cell were spindle,The collagen fibers aligned on the stress direction. Allograft cell were round-shaped.regular direction fibers showed up.Toluidine blue staining negative material was not observed in the both group at 3,8 weeks。The negative material was observed in the auto-allo-graft at 12 weeks,and at 24 Weeks the negative material was observed in the both group. According to immunohistochemical staining,vascular density in the auto-allo-graft was obviously higher than allograft at 8,12 weeks.The vascularity and cellularity in the center of the sample were significantly greater in the auto-allo-graft group than the allograft group at 3,8,12 weeks.(P<0.05),and less than allograft group at 24 weeks(p<0.05)Conclusion: After implantation,the intra-articular healing of auto-allo-graft undergoes the necrosis, revascularization, recellularization and ligamentation progress.Compared with auto-allo-graft,the ligameentization process of allograft significantly hysteresised.