A Histologic Study Of Anterior Cruciate Ligament Reconstruction With Double-layer Allograft Versus Single-layer Allograft In The Tendon-bone Tunnels Of Proximal Tibia And Intra-articulation In SD Rats

Objective: Anterior cruciate ligament(ACL)rupture is a common injury worldwide.Yet the predominant pathogenesis of ACL rupture may be attributed to traumatic causes.ACL rupture often results in knee instability.Subsequently,it not only increases articulation laxity,but also reduces activity.Finally,there is a high risk of knee osteoarthritis in the long term.So,with respect to a lot of treatments of ACL rupture,anterior cruciate ligament(ACL)reconstruction is the optimal treatment technique,aiming to restore native anatomy and a complete return to functional demands,particularly in young and active patients.Recently,for the ACL reconstruction,there is a key point that how a surgeon choose a appropriate graft according to different patients.The bone-patellar tendon-bone(BPTB)autograft has been regarded as the gold standard for ACL reconstruction.There is a great limitation,however,in that it results in distinct harvest-site morbidity that includes pain when kneeling.The BPTB allograft is designed as an option to overcome the disadvantages mentioned above,although the allograft has been criticized for its increased rate of laxity failure and graft re-rupture.To solve this problem,Wang et al.improved the traditional monolayer BPTB graft to make it a double-layer BPTB graft(DBPTB),which is stronger,provides a larger sectional area in the tunnel,and enhances the success rate of ACL reconstruction.In our study,we will mainly compare histology examination of ACL reconstruction with DBPTB allograft versus BPTB allograft in SD rats.Methods: Forty-six female mature SD rats(15 to 20 months)weighing greater than 0.3 kg were randomly divided into two groups.Group 1,24 SD rats,underwent an ACL reconstruction using a double-layer BPTB allograft;while Group 2,22 SD rats,underwent ACL reconstruction using a single-layer BPTB allograft.In addition,another 24 SD rats were used as the donor animals for source of allografts.And one of hind limbs was utilized for the DBPTB allograft,the other was used for BPTB allograft in each donor animal.Meanwhile,the donor animals were matched for age,sex,weight and height to the recipient animals.The required allografts were early prepared and should be frozen at-85? for ACL reconstruction.The histological observation of gross specimens was performed at 8 weeks and 16 weeks respectively.And every twenty SD rats(ten in each group)were killed at week 8 and week 16 respectively.In our study,the comparison of histology between DBPTB allograft group and BPTB allograft group was undertaken by light microscope to investigate that the modified sugrical procedure was a better option for ACL reconstruction.With respect to histologic evaluation,Graft vascularity and cellularity [1] were analyzed in gross specimens from the two groups.Yet,the histologic observation was mainly focus on the tendon-bone tunnels of proximal tibia and intra-articulation in our study.The analysis was performed using SPSS 13.0 statistical software(IBM,Chicago,IL,USA).Significance was set at P<0.05.Results: During the observation period,there were finally three SD rats dead,including two in DBPTB allograft group,and one in BPTB allograft group.After ACL reconstruction,two SD rats were infected,so the two SD rats were excluded from our study.Finally,there were forty-one SD rats left(twenty-one in DBPTB allograft group and twenty in BPTB allograft group)in our analysis.With respect to graft vascularity,there was significant differences both in the tibial portion and in intra-articulation at 8 weeks between DBPTB group and BPTB group(P<0.05).However,there was no significant differences at 16 weeks in the two groups(P>0.05).Similarly,with respect to graft cellularity,there was also significant differences in the tibial portion and intra-artiulation at 8 weeks between DBPTB group and BPTB group(P<0.05).Also,there was no significant difference at 16 weeks in the two groups(P>0.05).Conclusions: Based on our study results,we conclude that the modified surgical procedure(DBPTB)can achieve a better outcome than the BPTB on histology evaluation in SD rats.