Abstract:The applications and advancement of anterior cruciate ligament tissue engineering: reconstitute the ligament with biological function through the tissue engineering methods were comprehensively reviewed. Prospect along this direction was discussed. Some critical issues waiting for solving were also analyzed. Particularly, the choice and application of appropriate source cells, biological scaffold, surface modification, and growth modulators in this field were discussed.

Abstract:Objective To detect the expression of MMP-2 of posterior cruciate ligament (PCL) tissue after anterior cruciate ligament (ACL) injury. Methods The rat knee injury apparatus designed by our lab was used to injure ACL. Then, the expression of MMP-2 in PCL was detected at ex-vivo level with zymography. Results The expression of MMP-2 in PCL cultured supernatant fluid increased in a time dependent way after ACL injury. Conclusion PCL contributed to the accumulation of MMP-2 in the joint fluid after acute ACL injury.

Abstract:Objective To explore the role of synovium in the process of anterior cruciate ligament (ACL) injury by studying the effects of inflammatory on the activities of MMP-2,-9 under mechanical compression in human synoviocytes. Method We used an equi-biaxial stretch chamber with 12% mechanical injury compression and inflammatory factors (IL-1α and TNF-α) in human synoviocytes, and detected the activities of MMP-2,-9 under different conditions by zymography. Results Mechanical compression increased the MMP-2 production by 122% under 12% compression. In addition, TNF-α can also elevate the activity of MMP-2 in a time dependent way, while IL-1α cannot. However, mixture of these two factors dramatically increased MMP-2,-9 production. Mechanical injury had a strong synergistic effect on MMP-2,-9 productions with TNF-α and IL-1α. Conclusion Mechanical and inflammatory factors can elevate the activities of MMP-2,-9. Thus, synvoium might involve in regulating the micro-environment of joint cavity and the injury/healing process of knee joint tissue.

Abstract:Objective To investigate the biomechanical effects of the whole hardening of plantar soft tissue and the local hardening under metatarsal heards and calcaneus on human foot and ankle system. Methods Buliding a 3D finite element model based on the MRI scanning pictures of a healthy young volunteer and changing the material property of plnatar soft tissue to simulate different plantar soft tissue status; and three solutions simulatng the balanced standing were done to compare model’s prediction. In addition, the plantar pressure measurement of the volunteer was used to validite the model. Results The foot model was created and validated. Three solutions were completed under different material properties of plantar soft tissue, and the contact pressure distribution and some mechanical information of internal soft and hard tissue were quantified. Conclusion The hardening of plantar soft tissue, especially the local hardening, greatly affects the contact pressure distribution and stress magnitudes in plantar soft tissue, which would increase potential risk of plantar ulcer.

Abstract:Objective To analyze forearm-rotational effects on muscle electric activities of upper-limb during push-up. Methods The EMG of long and lateral heads of biceps brachii, anterior and medius deltoid, pectoralis major and biceps brachii for ten subjects during push-ups at three forearm rotations of internally rotated 90° (IR90), hand-neutral (NEU), and externally 90° (ER90) was collected. The root mean square (RMS) values of EMG were calculated and normalized. To determine whether there were differences between the EMG from the three positions, a One-Way ANOVA with factor rotational position was conducted on the normalized RMS values. The EMG profiles through a cycle were also displayed. Result From IR90 to ER90, there was no significant difference for the long head of biceps brachii, but a decrease for the lateral head of biceps brachii and medius deltoid, and an increase for anterior deltoid, pectoralis major and biceps brachii. The EMG profiles showed three patterns. Conclusion There were differences of electric activities for the muscles studied during push-ups at various forearm positions. However, these changes did not occur in the same way for the six muscles.

Abstract:Objective To investigate the high digital method of three- dimensional finite element model of the lower cervical spine with titanium mesh cage and plate after anterior cervical corpectomy by spiral CT,so as to provide standar d model for biomechanical experiment for anterior cervical corpectomy. Methods The lower cervical spine(C4-C7) geometries were determined from CT images of a 23 year old healthy man. The finite element model was constructed by the combination of software Mimics 9.1 and Freeform.The meshed model was acquired and finished with Ansys 9.0.With the pretreatment function of finite element software Ansys ,the structure of lamina terminalis,intervertebraldiscs,nucleuspulposus,anteriorlongitudinalligaments,sup-raspinal ligament were established supplementarily based on the osseous structure of spinal model. Based on the intact finite element model(FE/Intact), the model were generated by simulating anterior cervical titanium mesh fusion cage and plate after C5 corpectomy .Proper material features and entity unit type were used for intellectual finite element mesh division .Results Finite element mesh division of three- dimensional model of the lower cervical spine with titanium mesh cage and plate after anterior cervical corpectomy: Three- dimensional reconstructed software Mimics and finite software Ansys were used successfully to perform finite element mesh division of three- dimensional model of the lower cervical spine with titanium mesh cage and plate after anterior cervical corpectomy.Conclusions The constructed three- dimensional finite element model of the lower cervical spine with titanium mesh cage and plate after anterior cervical corpectomy approaches to real biomechanical sample,which can simulate the natural condition and facililate the further biomechanical research.

Abstract:Objectives To determine the influence of different lengths of the anterior odontoid screws on the fixation stability. Methods Twenty cadaveric C2 vertebrae were harvested and an osteotomy was performed to simulate a Type II fracture pattern in each vertebra. The angle of type II fracture line was 0°in 6 specimens, 17°in 8, and 25°in 6. In this way, Different lengths of fractured odontoid processes were created and then divided into 2 groups (<10mm vs >10mm). The fractures were then treated by anterior screw fixation. And insertional torque, and pull-out force and stiffness of the bone-screw was tested. Results The lengths of the screws bedded in fractured odontoid process were 8.3mm-12.3mm. The relationship between the pull-out strength (Y) and the length of the screw (X) was determined by the regression equation (Y=156.69+67.97X, r=0.28). However, No significant differences of the insertional torque, and pull-out force and stiffness of the bone-screw were found between the <10mm and >10mm groups. Conclusions Bone-screw stability is not closely related to the distal part of the fractured odontoid process. Anterior screw fixation could be used even when distal fractured part of the odontoid process less than 10mm.

Abstract:Objective To develop a biomechanical model of bone graft fusion of bilateral articular process combined with spinous process using 3D finite element method to explain its preventive role on postoperative correction loss for thoracolumbar fracture surgery, and to evaluate the effect on preventing postoperative correction loss than that of bone graft fusion simply in bilateral facet joints. Methods Computed Tomography (CT) scans were performed on L1-2 motion segment of the fresh spine specimen of an adult male cadaver, and mechanical model of functional spinal unit of L1-2 with vertebrae fracture affiliated disc serious damage were developed by defining injuried material properties. From simulating to dismantle internal fixation in patients who were dealed with bone graft fusion either of bilateral articular process combined with spinous process or simply in bilateral facet joints, two digitized surgical models were established by finite element method in Ansys 11.0 software platform. Four load conditions containing compression, anteflexion and retro-extension were added on digital fusion models on the basis of three-column spine theory to compute stresses/strains in bone graft and endplates and compressive displacements in damaged discs. Rusults Under the action of compressive load, anteflexion moment or post extension moment, the vertical compressive displacement and strain of disc annulus fibrous of the new fusion model (FSF) reduced significantly than those of the old one (FF), about 20%-35%; and the stress level of bone graft of articular process decreased too, about 5.5%-13%. The bearing capacity of bone graft between spinous process increased markedly up to 2.5-12.3 times or more than that of the interspinous and supraspinous ligaments. Conclusion After the fusions between the bilateral facet joint and the spinous process, the load bearing function of the spinal column is carried out mainly by three points of the spinous process and bilateral facets in three–dimensional space, and a new strengthening tension-band is formed by transplanted bone between spinous process. It can increase the three-dimensional stability of spinal segments, effectively relieve the stress concentration on the bone graft area of bilateral articular process, reduce the vertical compressive strains and displacements of the acutely injured disc, and can prevent the loss of postoperative correction for thoracolumbar fracture surgery.

Abstract:Objective we carried out a biomechanical comparison of a new point contact locking compression plate and the dynamical compression plate in in an osteoporotic comminuted radial fracture model. Methods Twelve pairs of aged osteoporotic cadaveric radii, 1cm mid-shaft transverse fracture were created to simulate comminuted fracture and fixed with PC-LCP、DCP, respectively. Then the anteroposterior four point bending、mediolateral four point bending and torsion tests was conducted to determine the bending、and torsion compress stiffness of the PC-LCP and DCP. Results Although both the bending and torsion stiffness of PC-LCP are higher than that of DCP, there are no significant differences. Conclusion The new PC-LCP has a tendency of the higher bending and torsion stiffness when used to fix the steoporotic comminuted radial fracture.

Abstract:Objective To explore the role of extracellular signal-regulated kinase (ERK) signaling pathway on cyclic strain induced proliferation of human periodontal ligament cell (hPDLCs). Methods The cultured hPDLCs in vitro were subjected to cyclic strain by FX-4000T system with 10 % or 20 %-elongation magnitude, 6 or 24 hours-duration respectively, at the same frequency of 0.1 Hz. The expressions of p-ERK1/2 and PCNA in hPDLCs were analyzed by Western blotting. To investigate the effect of p-ERK on cell proliferation, hPDLCs were incubated with PD98059, a specific ERK kinase inhibitor, and then the expression of PCNA was also analyzed by Western blot after hPDLCs were exposure to 10 %-cyclic strain at 0.1Hz-frequency for 6 hours. Result Cyclic strain increased the expression of PCNA and p-ERK1/2 in hPDLCs obviously, in which the magnitude and duration of cyclic strain had no significant difference. PD98059 could repress not only the activation of p-ERK1/2 but the expression of PCNA induced by cyclic strain in hPDLCs. Conclusion Cyclic strain promotes the proliferation of hPDLCs through ERK signaling pathway.

Abstract:Objective To investigate the compliance of small-diameter medical polyurethane artificial vascular graft, compared the micro-morphology and radical compliance of small-diameter medical polyurethane artificial vascular graft making in dry and wet; explored the effects on radical compliance causing by the sizes of the diameter and thickness of the artificial vascular graft; analysised the differences of compliance between different parts in artificial vascular graft when it was placed in the circulatory system. Methods The small-diameter artificial vascular graft with different morphology and different internal diameter and different wall thickness was prepared by casting polyurethane film onto the glass rod model. We get the pressure-diameter in a custom-designed pulsatile circulatory apparatus, calculate the radial compliance of artificial vascular graft based on the ISO7198 international standard. Results The morphology of artificial vascular graft in dry are dense; but the morphology of artificial vascular graft in wet are microporous which are even in size and distribution. The radical compliance is increasing gradually with the increase of artificial vascular graft diameter; but the radical compliance is decreasing with the increase of wall thickness; the radical compliance is different between the middle and the junctions of artificial vascular grafts, the larger fluctuation value of compliance appears in the export of artificial vascular; artificial vascular in wet have more superior radical compliance than artificial vascular in dry. Conclusions The medical polyurethane small-diameter artificial vascular graft has a excellent compliance, it is a promising materials which to be small-diameter vascular substitute. and there are many factors that will result in radical compliance mismatch, further research in radical compliance will be needed.

Abstract:Objective To investigate the effect of mechanical stretch force on the apoptosis, proliferation and differentiation of osteoblast culture in vitro. Methods Rat calvarial osteoblasts passage 2 to 4 were used and cell apoptosis was induced by serum starvation after 2 or 4 days of static culture. The osteoblasts were then subjected to 72 hours of cyclic equibiaxial stretch forces using Flexcell 4000TM strain unit. Apoptotic levels of the osteoblasts were quantified by flowcytometer right after the stretch application. The cell number and alkaline phosphatase (ALP) activity were also evaluated. Results After 2 days culture, 6% elongation of stretch force led to a 45% decrease of apoptosis rate, with a 34% increase of cell number. After 4 days culture, 13.6% elongation of stretch force elicited 192% increase of osteoblast apoptosis, while the cell population was decreased by 64%. ALP activity was declined upon the two magnitudes of force loading. Conclusions Stretching force can affect apoptosis in osteoblast culture. This regulative effect was magnitude sensitive controlling the osteoblast activity.

Abstract:Objective To explore the method in construction of the arterial network model of female rabbit genitourinary system in application of different concentrations of perfusion fluid and different ways of infusion, laying foundation for the construction of the arterial network of digital human genitourinary system. Methods The three different concentrations of chlorinated poly vinyl chloride , that were 20%, 10% and 8% respectively, were prepared for perfusion fluid to construct the female rabbit genitourinary arterial network system through the abdominal aorta (group A) and abdominal aorta and bilateral femoral artery(group B) which were two ways of infusion, and then to analyze the expression of the cast specimens’ blood vessels . Results The arterial vascular network models of female rabbit genitourinary system ,which were injected with different concentrations of fillers and through different ways of infusions, showed a significant difference in performance: (1)the model of high concentration group resulted in obvious interrupted branches and uneven distribution. It only showed the mainly arteries but for the small artery branch, imperfectly.(2) the model of middle concentration group showed the mainly arterial course with no significant fault branches; and the distribution of vascular network is full and clear , (3) the model of low concentration group showed the mainly arteries clearly but too more periphery ones and some branches had gathered together . Conclusion The model constructed with the 10% vinyl chloride infusion liquid and through the abdominal aorta and bilateral femoral arteries simultaneously, could clearly display the full arterial vascular network.

Abstract:Through using the method of literature and video statistics, acknowledge the idea of core strength training and introduce this idea to the swimming training. By way of practice and experience accumulated, taking the male and female swimmer from Shanghai swimming team as research subject, after 3 weeks core strength training, most swimmer achieved good performance on swimming starting technique.