Biological Bone Cross-pin On The Basic Application Research Of Anterior Cruciate Ligament Reconstruction In Goat Model

Rigidfix system are widely used in anterior cruciate ligament reconstruction(ACLR) because of its little interference on MRI examination after surgery, joint lineadjacentfix-point, and omnidirectional attachment with bone-tunnel though tendon graft. Yet, risk of postoperative osteolysis and pin-breakage, as well as its expensive cost, limit its further application. Clinical application of Biological bone, known as Allogenous Cortical Bone(ACB), has a history of over a century owning to its good biomechanical properties, excellent effect of bone conduction and induction. In order to reveal the difference between ACB and Rigidfix system from perspective of biomechamics, imageology and histology, more importantly, to explore the possibility of clinical application of ACB in ACLR, two sets of experiment was designed.Part I:Experimental study of ACB in ACLR in vitroMethods:ACLR was simulated by 24 cases of fresh frozen goat knee joint. The experimental group was the Biological bone cross-pin group (n=12), and the control group was Rigidfix group (n=12). Biomechanical experiments include displacement data, failure load, maximum load, etc. Slope of linear stage of load displacement was chosen as the tensile stiffness. Experimental data were analyzed by statistical methods, choosing P= 0.05 as the significance level.Results:In cycling test, the displacement at cycle 1,30,200,400 and 1000 exhibited no significant difference between Allogenous Cortical Bone Cross Pin group and Rigidfix group, P> 0.05.The maximum failure load, yield load,and stiffness have no statistical significance between Allogenous Cortical Bone Cross-pin group(Maximum failure load: 944.225N. Yield load:864.864N. Stiffness:237.215N/mm) and Rigidfix group Maximum failure load:900.568N. Yield load:807.473N. Stiffness:237.215N/mm).Conclusions:Allogenous Cortical Bone Cross-pin and Rigidfix have no statistical significance in vitro biomechanical, prompt Allogenous Cortical Bone Cross-pin has the potential to clinical application.Part ?:Experimental study of ACB in ACLR in vivoMethods:28 goats were used to establish the experimental animal model of ACL reconstruction. Using the paired design method, randomly choose the left or right knee as the experimental or control group. The experimental group use the biological bone cross-pin to perform the ACL reconstruction, while the control group use the rigidfix. At 0,6,12 and 24 weeks,7 randomly selected animals were sacrificed respectively. Among the 7 goats sacrificed each time,5 (add up to 10 knees) were designed to do the pull-out biomechanical experiment, while the other 2(4 knees) were applied to do the routine histology dyeing(HE and Masson tricolor).All of the knees went through X-ray examination.Results:At 6 weeks, the Maximum failed load(MFL), Yield Load(YL) and stiffness are measured, the values of biological bone cross-pin group are 260.354N±48.055N, 223.579N±42.632N,159.372±10.512N/mm respectively, correspondingly, the values of rigidfix group are 260.354N±48.055N,223.579N±42.632N,159.372±10.512N/mm. At 12 weeks, the MFL, YL and stiffness values of biological bone cross-pin group are 320.339N±60.127N?270.382N±50.172N?102.765 ± 9.347N/mm respectively, correspondingly, the values of rigidfix group are 300.768N±51.352N?211.121N± 49.194N?95.686±9.131N/mm. At 24 weeks, the MFL, YL and stiffness values of biological bone cross-pin group are 600.569N±56.125N?560.213N±40.672N?53.421 ±8.472N/mm respectively, correspondingly, the values of rigidfix group are 577.256N ±47.357N?510.148N±59.327N?50.853 ± 7.313N/mm. There is no significant differences among the two groups at each point of time (P>0.05).Failure mode:at the early stage(during 6 weeks),the grafts are pulled out by pins cutting.At the late stage(24 weeks),the grafts are mostly ruptured at the tibial tunnel or femoral tunnel entrance.Tissue healing between the two groups are both in good condition.No breakage in Biological bone cross-pin groups,1 case of breakage in Rigidfix groups.Conclusions:Biological bone cross-pinin the biomechanical performance is better than the Rigidfix, but no significant difference between the two, there is no statistical significance.From imaging and histological observation of the healing process there has no obvious difference. Biological bone cross-pin has the feasibility of clinical application.