Biomechanical Study Of Microfracture Combined With Platelet-rich Plasma For The Treatment Of Chondral Defect In A Rabbit Knee

Objective: Anterior cruciate ligament(Anterior Cruciate Ligament,ACL)injury was a common kind of knee disease in clinical,which was mainly caused by the motion trauma.However,since the anterior cruciate ligament possess peculiar biological environment and a lack of blood supply,when it was injuried,it was hard to self-healing.After anterior cruciate ligament injuried,the function of limits the role of the tibia forward was damaged that seriously affecting the stability of the knee,if not treatment in time may be secondary to degeneration of cartilage and meniscus,traumatic arthritis and other disease.Currently,besides some patients refused surgery for any personal reasons or can not tolerate surgery themself,most patients choose surgery.Anterior cruciate ligament reconstruction is a well-known worldwide and mainly surgical treatment for Anterior cruciate ligament injuriedbecause of effective and a good results.Today,when after anterior cruciate ligament reconstruction done,the rigorous,active and effective rehabilitation exercises should be developed,such as early weight-bearing exercises and muscle strength recovery,which implant higher strength requirements for grafts.Thus,there are most important role of anterior cruciate ligament graft in surgery,the success of the procedure,postoperative knee rehabilitation exercises and functional recovery were affects by it as important factors.More and more scholars started to explore and research in that the choice of grafts in anterior cruciate ligament reconstruction surgery.Postoperative the function of stability to knee joint is determined by the biomechanical function of the grafts.Therefore,compared with the histological characteristics of ligament grafts,which are as same as important to restore biomechanical function.In the current anterior cruciate ligament reconstruction with hamstring tendon and bone-patellar tendon-bone is more commonly to used as autografts and allografts.When reconstruct finished,recovery of a ligament functional is associated with the initial strength of the grafts.Clinically,the potentioal problems should be solved because of hamstring tendon with its relatively large cross-sectional area,sufficient length and greater strength that is caused by the initial grafts strength is not enough potential.This experiments was designed to compare biomechanical changes of autologous semitendinosus tendon and semitendinosus tendon of deep-frozen allograft reconstruction in anterior cruciate ligament,through a comparative study of the two grafts in biomechanics,and to make a dynamic evaluation of its efficacy,provide a theoretical basis for clinical work in the end.Methods:1 Complete semitendinosus grafts of 8 New Zealand adult rabbits were removed from hind limbs under sterile conditions.Just removed the fresh grafts after washed by normal saline into a sterile container sealed airtight.Using cryogenic freezing technology to keep graft in a sterile container of liquid nitrogen tank(temperature-196?),as deep-frozen allograft tendon randomly.2 5 New Zealand adult rabbits were anesthetized to sacrifice.The bilateral hind limbs were cut off from proximal femur and distal tibia.5 of the samples were obtained to remove the redundant tissue.The maximum load and maximum displacement of the normal anterior cruciate ligament were measure.3 15 New Zealand adult rabbits were numbered randomly,at first,complete semitendinosus taken of from left hind in odd arrays and right hind in even arrays under sterile conditions,which correspond to the numbers relative to rabbits numbers,as autologous semitendinosus tendon when we used in anterior cruciate ligament reconstruction.Anterior cruciate ligament reconstruction was performed in odd number of rabbits with autologous semitendinosus tendon grafts in left knee and deep-frozen allogeneic semitendinosus tendon graft in right knee.Even-numbered contraried to odd group about treatment.Of course,all of the operation followed the principle of sterile surgery strictly.Infection was prevented that given antibiotics preoperative and postoperative to treatment.4 Animals were sacrificed respectively for drawing materials after 4 weeks,8 weeks and 12 weeks,and then on the case of the appearance of the graft was generally observed and recorded.Experimented and measuried properties of biomechanical that autologous tendons and deep-frozen allograft tendons appearing,including the maximum load,maximum stress and maximum displacement.The experimental data should be obtained to analysis with the software for statistical,then we could comparaed properties of biomechanical of two graft which was used in anterior cruciate ligament reconstructive surgery.Results: 1 General observation: After operation,three animals were died due to early infection and the rest of animals growth normally,no significant immune rejection.After 4 weeks,8 weeks,12 weeks we discoveried that the allogeneic semitendinosus tendon graft of anterior cruciate ligament reconstruction group some obvious presence within the graft and a little relaxation that happened in keen joint deformation.There is none of effusion or a small amount of effusion,intraarticular adhesions of joint unconspicuous.Graft surface have a small amount of synovial covering at 4 weeks,graft surface is overwritten by synovial hyperplasia at 8 weeks and 12 weeks.2 Biomechanics: The maximum load of normal anterior cruciate ligament was(307.59 + 9.45)N,and the maximum displacement was(3.03 + 0.22)mm.After 4 weeks,8 weeks,12 weeks the data of autologous tendon graft group or deep-frozen allogenic tendon graft maximum load,maximum stress and maximum displacement was statistically significant(P <0.05).The autologous tendon graft group and deep-frozen tendon allograft group was set at the maximum load,maximum stress and maximum displacement was not statistically significant(P> 0.05).Conclusion:The biomechanical performance of autologous tendon and deep frozen allograft tendon in anterior cruciate ligament reconstruction at early time was not little difference,with the passage of time,maximum load and maximum displacement increasing.At the same time,autologous tendon and deep frozen allograft tendon strength recovery of roughly the same.Deep frozen allogene does not reduce the mechanical properties of tendon graft.A high degree of similarity to the biomechanical properties of autologous tendon and tendon allograft,therefore in clinic should be considered other factors for anterior cruciate ligament reconstruction for patients with graft.