| The ACL (anterior cruciate ligament) injury may cause knee joint instability andinjury of other structures within the joint serious knee damage, ACL reconstructionunder arthroscopy is popularized to restore knee stability. Graft of ACL reconstructioninclude autologous tendon allograft tendons and artificial ligaments. Early artificialligament defects in the materials and design with clinical complications have beeneliminated, but due to the advantage, and the rapid development of materials, theresearchers continue to improve and pay attention to artificial ligament. In recent yearsby the PET (polyethylene terephthalate) developing and designation promoting, LARS(ligament advanced reinforcement system) artificial ligament, the innovative design inthe joint cavity with free, parallel and open-weave fiber, bone tunnel part of cylindricalthree-dimensional woven, and with appropriate porosity at both ends of the titaniumscrew extrusion fixed was implied. Clinical follow-up reports of LARS artificialligament has a good short-term and medium-term postoperative results and high patientsatisfaction, but with the ligament long-term stability, durability and biocompatibility,and biomechanical properties of the maintenance, is still few reported. Besides, theartificial ligament reconstruction surgery indications, treatment of fracture ligamentstump issues, are still controversial and need to be revealed.To reveal the compatibility and biomechanical characteristics results of LARSartificial ligament reconstruction ACL, and to clear the role of the ligament stump. Weuse the LARS artificial ligament reconstruction goat ACL, after the remaining orremoval of a stump of ACL for20months. Then examined by means of histology andelectron microscopy to investigate the structure and organization; Imageology studies to clarify the interactive with the host structure; biomechanics to detect the maximumtensile strength. This study included the following three parts:The first part: Histological and imageologic research of LARS artificialligament reconstruction ACLObjective: To establish the LARS artificial ligament reconstruction goat ACLanimal models and to assess the stability and applicability of the model. Makemacroscopic and microscopic observation of LARS artificial ligament reconstructionACL20months, to discuss the relationships between LARS ligament and autologoustissues.Methods:20months after animal models reconstruction. Observation ofspecimens both macroscopic and microscopic. HE staining, Masson staining with lightmicroscopy; scanning electron microscopy of the structure; imaging observation ofpostoperative complications also observed.Results: One in each group goat died at12and16months post-operatively. Thespecimens were storage in refrigerator.20weeks after operation, general observationand physical examination were executed, no knee swelling or deformity, incisionhealing well, force line and joint activity was normal. Meniscus, cartilage and otherstructures within the joint was in good condition, no synovial tissue proliferation, thefree part of the LARS artificial ligament joint was partly covered by synovial membrane.Irregular fibrosis tissues encapsulated the LARS ligament, the specimens with retain thestump seem to have more tissues around the tibial attachment than the removed ones.One in each group was observed of femoral titanium screw slippery by imageologyexamination. LARS ligament was wrapped and ingrowthed by fibrous tissues. Theingrowthed fibrous autologous were confirm to be mature by Masson staining. Tissuesin tunnel parts was allied similarlly, the fibrous tissue contact the tunnel directly.Fibrous tissue wrapped and ingrowthed with polyester was observed by scanningelectron microscope. The bone tunnel expansion of the signs, synovial fluid infiltrationof the bone tunnels by imageology examination.Conclusions: LARS ligament could induce the fibrous tissues both in intro-articular and bone tunnel part; LARS ligament do not cause the synovitis directly;LARS ligament shows a good biocompatibility. The second part: Biomechanical experiments of LARS artificial ligamentwithin ACL reconstructionObjective: To obtain biomechanical parameters after ACL reconstruction byLARS ligament20months post-operatively.Methods: The the knee specimens were trimed, the patellar, excess soft tissue,muscle, joint capsule, meniscus and posterior cruciate ligament were all removed, withretaining ACL part as the only connection of femur and tibia.15cm to joint line wascutted to faciliated tibia and femur fixation. The specimen is fixed on the biomechanicalmachine. Adjustment was made to confirm LARS artificial ligament in a straight linewithout torquing or banding. So that the tension forces could totally exerted on LARSligament. Two specimens in each group were randomly selected to tensile testing withremove the fixed screws, the rest four specimens under tensile testing with remainingmetal screws.10minutes of pre-tension of10N,10mm per minute Constant Velocitytensile exerted on specimens, frequency of20Hz to be recorded, until the prosthesisbreakage or slippage failure.Results: specimens with remove titanium screws could not afford sufficient tensilestrength, the average pulling force is less than300N, tensile testing ended of LARSartificial ligament slippage in the bone tunnel; the two specimens with femoral screwslippage gained the maximum tensile force of lower than900N, was also ended withgraft slippage.Conclusions: LARS ligaments in the joints environment could maintain its largertensile strength without apparent fatigue. Fixed titanium screws still play the key role inLARS ligament fixation.The third part: The clinical application of LARS artificial ligament in ACLreconstructionObjective: To evaluate the function and satisfaction of LARS artificial ligamentreconstruction ACL after3-7years, the morphology of the LARS artificial ligaments inthe human tissue.Methods: Using LARS artificial ligament reconstruction ACL in clinics.57patients (58knees), from injury to surgery time is divided into acute, chronic damage tothe two groups, their retrospective analysis of multiple indicator. Reoperation cases (3cases of knee) on the LARS artificial ligament material histological observation.Results: The LARS artificial ligament ACL reconstruction with postoperative joint function, the level of knee joint motion was significantly higher than preoperative (P<0.01); subjective objective assessment of knee function between the two groups nosignificant difference (P>0.05); imageology examination (X-ray and MR) showed theexistence of osseous tunnel expansion in1.5years post-operatively; no significantcorrelation between joint stability and bone tunnel enlargement (P>0.5). The tibial andfemoral tunnel enlargement incidence no statistics differences (P>0.05). Histologywere observed under two years after surgery regularly arranged fibrous tissue ingrowthLARS artificial ligaments between the bundles of polyester.Conclusion: LARS artificial ligament ACL reconstruction can restore kneefunction and high satisfaction. LARS artificial ligaments after ACL reconstruction withbone tunnel expansion exists, and stabilized in1.5years, the joint stability of thepostoperative bone tunnel enlargement was no correlation. LARS artificial ligamentafter ACL reconstruction showed a good biocompatibility. The assessment between theacute injury and chronic injury had no significant differences. |
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