The Clinical, Biomechanical And Related Basic Research Of Anterior Cruciate Ligament Reconstuction With PET Artificial Ligament

Anterior cruciate ligament (ACL) injury results in instability of the knee and damage of its function. ACL reconstruction is the main treatment option for ACL injury, and it is always the research focus in sports medicine area. ACL reconstruction grafts include auto graft, allograft and artificial ligament. The previous artificial ligaments have been abandoned because of the high failure rate. As both of autograft and allograft have some drawbacks that could not be overcome, artificial ligament has been recently reconsidered for ACL reconstruction choice. The modified polyethylene terephthalate (PET) artificial ligament has been used for ACL reconstruction clinically, but its clinical outcome and safety over two years after surgery are still unknown and less reported. Currently, basic research of artificial ligament focus on how to improve the biocompatibility of PET material, but the advancement is too minimal to meet the need of clinical practice. Some drawbacks of the modified PET artificial ligament used in clinic have been found with the poor biocompatibility of PET material. The healing between the both ends of the PET artificial ligament with the bone tunnel is not firm, and the fixation of the artificial ligament is dependent on the interference screw. Also, the tissue growth into the free bibers of intra-articular part of the artificial ligament is poor, so the long-term clinical outcome could not be guaranted. If the nano technology surface modification improve the biocompatibility of the PET artificial ligament material, and make for the raise of the long-term outcome of artificial ligament?In order to understand the current situation and true fact after ACL reconstruction using PET artificial ligament and to solve the questions above-mentioned, a multicenter study was underwent to evaluate the clinical outcome of ACL reconstruction using the Ligament Advanced Reinforcement System (LARS) artificial ligament with 3-to 5-year follow up. The rotational stability of the knee and function of the lower limb during walking were quantitatively evaluated by use of three-dimensional gait analysis technology on patients who underwent ACL reconstruction using LARS artificial ligament and hamstring autograft. Human bone mesenchymal stem cells (hBMSCs) were cultured on PET artificial ligament materials which have been coated with chitosan and hyaluronic acid or nanohydroxyapatite by use of layer-by-layer nano self-assemble, and the adhesion, proliferation and differentiation of the hBMSCs were observed. This study included three parts as follows.PartⅠAnterior Cruciate Ligament Reconstruction with LARS Artificial Ligment:A Multi-center StudyPurpose Multicenter study to evaluate the clinical outcome of anterior cruciate ligament (ACL) reconstruction by use of the Ligament Advanced Reinforcement System (LARS) artificial ligament with 3-to 5-year follow up.Methods From August 2004 to July 2006,159 patients with ACL rupture underwent arthroscopic ACL reconstruction with LARS artificial ligament at 4 orthopaedic sports medicine centers. They were retrospectively followed up for 50 months (36 to 62 months). Outcome assessment included physical examination, KT-1000 arthrometer testing, magnetic resonance imaging, radiography, Lysholm score, Tegner score, International Knee Documentation Committee score, and subjective satisfaction rate. Quadriceps and hamstring isokinetic strength was evaluated in 68 patients.Results The side-to-side difference in anterior translation (injured side-uninjured side) measured by KT-1000 arthrometer was 1.5±1.6 mm postoperatively, and knee stability was significantly improved compared with preoperative data (P<.0001). The Lysholm score improved from 65.1±12.3 points preoperatively to 94.5±7.0 points postoperatively (P<.0001). The Tegner score improved from 3.1±1.6 preoperatively to 6.1±1.5 postoperatively (P<.0001). According to the International Knee Documentation Committee score,94%patients were graded A or B at the last follow up. The rate of bone tunnel enlargement was 51%(80/156). Ninety-three percent of patients were very satisfied or satisfied with their outcome. Quadriceps and hamstring isokinetic peak torque of the injured limb expressed as a percentage of the contralateral limb was 93.6±10.7 and 95.8±12.0, respectively. Total 11 cases underwent the failure with the rate of 7%, including 3 cases with interference screw loose,4 cases with knee laxity due to surgical technical mal-position of bone tunnel,3 cases with artificial ligament rupture and one case accompanied synovitis.Conclusions ACL reconstruction with LARS artificial ligament used in patients with the ACL stump preserved in the acute and chronic phases has a very good outcome at mean of 50 months'follow up. The overall failure rate for ACL reconstruction with LARS artificial ligament was 7%, and one case with knee synovitis.PartⅡThree-Dimensional Gait Analysis for Knee Stability After ACL Reconstruction with LARS Artificial LigamentPurpose To evaluate the dynamic rotation stability of the knee and lower limb function in patients who had undergone anterior cruciate ligament reconstruction by use of LARS artificial ligament and hamstring autograft using single bundle technique.Methods Three groups were compared:eight LARS artificial ligament reconstruction patients, eight hamstring autograft anterior cruciate ligament reconstruction patients, and 8 matched control.All patients received the operation before 12 months when the gait analysis was performed and they all returned to the sports activity before injury. A 3-dimension motion analysis and force plate system was used to determine sagittal plane kinematics and kinetics of the lower limb during walking. Each subject underwent 3 trials and the mean were as their results. Visual 3D software was used to resolve the data. Variable analysis included step length, step speed, and stance of gait cycle percent, the angle of knee flexion, extension, and rotation. The sagittal vertical ground reaction force was also analyzed.Results There was no statistically significant difference between the three groups with respect to the step length, step speed, and stance of gait cycle percent (p>0.05).The knee flexion and extension at heel contact in LARS group, HT group and control were 3.0±1.4,2.8±1.6 and 2.7±2.1, respectively. The maximal and minimal knee flexion and extension during stance in LARS group, HT group and control were 33.2±9.6 and 7.0±3.1,33.5±10.8 and 7.7±3.8,32.8±5.7 and 7.2±3.4, respectively; and there was no significant difference between the three groups (p>0.05).The maximal knee internal rotation in LARS group, HT group and control were 6.2±1.6,5.8±1.3, and 5.2±1.8, respectively, and there was no significant difference between groups (p>0.05). The maximal knee external rotation in LARS group, HT group and control were 7.8±1.1,8.2±1.4, and 5.6±1.9, respectively. The values of LARS group and the HT group were more larger than the control, and indicating a significant difference (p<0.001); there was no significant difference between the HT group and the LARS group (p>0.05).The sagittal vertical ground reaction force:the first peak force of LARS group, HT group and control were 120.8±15.3,119.7±12.8 and 121.1±19.0, respectively; the valley force of LARS group, HT group and control were 73.0±12.9,72.6±13.7 and 68.9±13.0, respectively; there was no significant difference between the three groups (p>0.05). As for the second peak force, the force change in the midfoot, and the first peak time, there was no significant difference between the three groups (p>0.05).Conclusions The time-spatial data, sagittal knee angle, and sagittal vertical ground reaction force return to normal level during walking at 1 year after anterior cruciate ligament reconstruction by use of LARS artificial ligament or hamstring autograft using single bundle technique, but the knee rotation does not resume to normal level.Part III Effect of Nanoscale Coating for PET Materials on Adhesion, Proliferation and Differentiation of Mesenchymal Stem CellsPurpose To observe the effect of chitosan, hyaluronic acid and hydroxyapatite nanoscale coating for polyethylene terephthalate (PET) material on adhesion, proliferation and differentiation of human Bone Marrow mesenchymal stem cells (hBMSCs).Methods The hBMSCs were cultured on the PET coating of nanoscale chitosan, hyaluronic acid and hydroxyapatite, and the adhesion, proliferation and differentiation of hBMSCs were observed. The PET film were divided into three groups based on the surface modification using layer-by-layer of chitosan and hyaluronic acid (LBL group), LBL plus nano hydroxyapatite coating (HA group), or without treatment (PET group). The morphology of hBMSC were observed by scanning electron microscope (SEM) at 24 hours and 7 days after seeding. The proliferation and the alkali phosphatase (ALP) activity of hBMSCs were detected when cultured for 7 days. Real Time PCR was used to measure the mRNA expression of integrinβ1 at 3 days culture.Results The hBMSCs showed better spreading in the HA group and LBL group than the PET group. The proliferation and ALP activity of hBMSCs of the HA group and LBL group were significantly higher than the PET group (<.001). The proliferation of the HA group was significantly higher than the LBL group (p=0.01), and the ALP activity of the HA group was also higeher than the LBL group (p<.001).As for the mRNA expression of integrinβ1 at 3 days after seeding, the HA group and LBL group were significantly higher than the PET group (<.001), and the HA group showed significantly higher than the LBL group (p=.003).Conclusions The chitosan, hyaluronic acid and hydroxyapatite nanoscale coating for PET material significantly improve the adhesion, proliferation and differentiation of hBMSCs. The effect of nano hydroxyapatite is more notable.