| Background and ObjectiveAnterior cruciate ligament (ACL) injury is a common injury of the knee. ACL is an important structure to ensure the knee's stability and lack the ability of healing itself after injury. Anybody who can't endure forgiving sports should be treated by operation. Developments in arthroscopic techniques and tools and improvement in technology and research have made ACL reconstruction a safer and safer operation. The keys to support a successful reconstruction and accelerated postoperative rehabilitation program are the fixation and tendon healing in the bone tunnel. Auto graft such as bone-patellar-bone, hamstring, allograft, man-made ligament or histoengineering ligament is usually used as replacement in the reconstruction. Allograft is an ideal option to minimal the complication such as patellar fracture, quadriceps weakness, patellofemoral pain and so on. It is especially suit for high level player and revision operation. The healing of the allograft in the bone tunnel is still not clear. The researches of that are rare. Transfer growth factor B is an important cytokine in the course of soft tissue healing, it can accelerating the express of collagen I , III. Two-step deep-frozen is a useful way to avoid the immunological reaction after reconstruction. In this experiment, the indirect articular suspending fixation animal model are established, deep-frozen allograft are planted with TGF-8, observe the healing course of graft-bone tunnel, and the influence of TGF-βon this course.MethodsThirty-six New Zealand and white rabbits are divided randomly into three groups including TGF-βgroups, allograft groups, autograft groups. There are twelve animals (24 knees) each group. Tendons are established through indirect articular suspending fixation during ACL reconstruction. Specimens were harvested 4, 6, 8 weeks after reconstruction. After macroscopical observation, Specimens were treated for histological and biomechanical test. All data are handled by SPSS 10.0. ResultsAt individual time points of this experiment, the biomechanical results (maximums pull-out power)of the TGF-βgroup, autograft group and allograft group have significant differences compared with each others (P<0.01). Macroscopically,no obviously immunological reaction are seen,no loose . Historically, TGF-βgroup and autograft group healed at eight weeks after operation. Some tissue like trabecula can be seen in these groups. Only fibers can be seen in autograft group at eight weeks. No obvious immunological reaction is seen in the bone-tunnels reconstructed by deep-frozen allograft, but it is loose obviously.Conclusions1. Two-step deep-frozen allograft has no obvious immunological reaction after reconstruction, but can be loose. It may have relationships towards the late healing of allograft.2. The indirect articular suspending fixation has important influence on graft healing, the graft healing is more excellent in bone-tunnel than in articular line, this kind of healing is so-called direct healing. It suit for the accelerated postoperative rehabilitation program.3. TGF-βis useful in accelerating the healing course of allograft with bone-tunnel. The exact mechanism is still not very clear. Someday, TGF-βmaybe can be used in clinical ,but there still a long way to go.
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