Research on Surface Treatment and Interfacial Bonding Technology of Copper-Polymer Direct Molding Process.

To realize the connection of copper and Polyphenylene sulfide (PPS) by metal-polymer direct molding, this paper combined anodic oxidation and chemical corrosion to treat the surface of copper, and carried out the injection molding experiment. An orthogonal experimental arrangement was used to identify the optimal electrolyte and etching solution for preparing a microstructure on a copper surface. The bonding and fracture mechanisms of the copper-polymer assembly were investigated through injection molding experiment and SEM technology. The results revealed that the phosphoric acid concentration had the most significant effect on the microstructure quality and etching solution containing 20% phosphoric acid produced a uniform microstructure with 25.77% porosity and 5.52 MPa bonding strength. Meanwhile, SEM images of the interface from bonding to fracture in the copper-polymer assembly indicated a well-filled polymer in the microstructure with a mainly cohesive fracture mode.

An optimization method for implantation parameters of individualized TKA tibial prosthesis based on finite element analysis and orthogonal experimental design.

BACKGROUND: Individualized and accurate implantation of a tibial prosthesis during total knee arthroplasty (TKA) can assist in uniformly distributing the load and reducing the polyethylene wear to obtain a long-term prosthetic survival rate, but individualized and accurate implantation of a tibial prosthesis during TKA remains challenging. The purpose of this study was to optimize and individualize the positioning parameters of a tibial prosthesis to improve its accurate implantation using a new method of finite element analysis in combination with orthogonal experimental design. METHODS: Ten finite element models of TKA knee joint were developed to optimize the implantation parameters (varus angle, posterior slope angle, and external rotation angle) of tibial prosthesis to reduce the peak value of the contact pressure on the polyethylene liner according to the method of finite element analysis in combination with orthogonal experimental design. The influence of implantation parameters on the peak value of the contact pressure on the polyethylene liner was evaluated based on a range analysis in orthogonal experimental design. RESULTS: The optimal implantation parameters for tibial prosthesis included 0° varus, 1° posterior slope, and 4° external rotation. Under these conditions, the peak value of the contact pressure on the polyethylene liner remained the smallest (16.37 MPa). Among the three parameters that affect the peak value of the contact pressure, the varus angle had the greatest effect (range = 6.70), followed by the posterior slope angle (range = 2.36), and the external rotation angle (range = 2.15). CONCLUSIONS: The optimization method based on finite element analysis and orthogonal experimental design can guide the accurate implantation of the tibial prosthesis, reducing the peak value of the contact pressure on the polyethylene liner. This method provides new insights into the TKA preoperative plan and biomechanical decision-making for accurately implanting TKA prosthesis.

Optimization of parameters for femoral component implantation during TKA using finite element analysis and orthogonal array testing.

BACKGROUND: Individualized and accurate implantation of a femoral component during total knee arthroplasty (TKA) is essential in achieving equal distribution of intra-articular stress and long-term survival of the prosthesis. However, individualized component implantation remains challenging. This study aimed to optimize and individualize the positioning parameters of a femoral component in order to facilitate its accurate implantation. METHODS: Using computer-simulated TKA, the positioning parameters of a femoral component were optimized individually by finite element analysis in combination with orthogonal array testing. Flexion angle, valgus angle, and external rotation angle were optimized in order to reduce the peak value of the pressure on the polyethylene liner of the prosthesis. RESULTS: The optimal implantation parameters of the femoral component were as follows: 1° flexion, 5° valgus angle, and 4° external rotation. Under these conditions, the peak value of the pressure on the polyethylene liner surface was minimized to 16.46 MPa. Among the three parameters, the external rotation angle had the greatest effect on the pressure, followed by the valgus angle and the flexion angle. CONCLUSION: Finite element analysis in combination with orthogonal array testing can optimize the implantation parameters of a femoral component for TKA. This approach would possibly reduce the wear of the polyethylene liner and prolong the survival of the TKA prosthesis, due to its capacity to minimize stress. This technique represents a new method for preoperative optimization of the implantation parameters that can achieve the best possible TKA outcome.

Qing Hua Chang Yin inhibits the LPS-induced activation of the IL-6/STAT3 signaling pathway in human intestinal Caco-2 cells.

Increasing evidence indicates that the pathogenesis of ulcerative colitis (UC) is highly regulated by the interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (STAT3) pathway and its negative feedback regulator, suppressor of cytokine signaling 3 (SOCS3). Therefore, modulating the signaling feedback loop of IL-6/STAT3/SOCS3 may prove to be a novel therapeutic approach for the treatment of UC. Qing Hua Chang Yin (QHCY) is a traditional Chinese formulation that has long been used in clinic for the treatment of UC. We have previously reported that QHCY ameliorates acute intestinal inflammation in vivo and in vitro through the suppression of the nuclear factor-κB (NF-κB) pathway. In the present study, in order to further elucidate the mechanisms responsible for the anti-inflammatory activities of QHCY, we stimulated human intestinal Caco-2 cells with lipopolysaccharide (LPS) to create an in vitro model of an inflamed human intestinal epithelium, and evaluated the effects of QHCY on the IL-6/STAT3/SOCS3 signaling network in inflamed Caco-2 cells. The levels of IL-6 were measured by ELISA and the levels of STAT3 and SOCS3 were measured by western blot analysis. We found that QHCY significantly inhibited the LPS-induced secretion of pro-inflammatory IL-6 in the Caco-2 cells in a dose-dependent manner. Moreover, QHCY profoundly suppressed the LPS-induced phosphorylation of Janus-activated kinase 1 (JAK1), JAK2 and STAT3. Furthermore, treatment with QHCY markedly augmented the expression of SOCS3. Taken together, the findings of the present study suggest that the modulation of the IL-6/STAT3/SOCS3 signaling network may be one of the mechanisms through which QHCY exerts its anti-inflammatory effects.

Accurate movement of jaw segment in virtual 3D orthognathic surgery.

In traditional virtual 3D orthognathic surgery, after repositioning the maxillary segment to the desired position, surgeons usually roughly rotate or adjust the mandibular segment to obtain a relatively good relationship with maxillary dentition to calculate the virtual terminal occlusion splint. However, surgeons are not easy to avoid penetrability, overlap, or an overly large space existing between the maxillary and mandibular dentitions during this process. The present report offered a new method to obtain a suitable virtual terminal occlusal splint that could avoid penetrability, overlap, or an overly large space between the maxillary and mandibular dentitions, and simultaneously accurately moving the maxillary or mandibular segment to the desired position utilizing the planned terminal occlusion plaster models in virtual orthognathic surgery. For double jaw surgery, after aligning the planned plaster models to the 3D maxilla and mandible, we could simultaneously move the maxillary and mandibular segment as a whole that maintain the planned terminal occlusion to the desired position. This present method may enhance the accuracy of 3D virtual orthognathic surgery and save plenty of time spend on virtual surgery simulation, which also offers a useful educational method for training junior surgeons and students.

Finite element analysis of type B condylar head fractures and osteosynthesis using two positional screws.

OBJECTIVE: The aim of this study was to explore the cause of type B condylar head fracture after parasymphyseal impact, and evaluate the biomechanics of osteosynthesis using two positional screws for the repair of this type of fractures. METHODS: A finite element model of the mandible was created, and a parasymphyseal impact was simulated using Mimics 10.01 and Abaqus 6.10 software. The type B condylar head fracture was simulated in the right condyle using a mimics simulation cut with polyplane module according to the analyzed results together with clinical experience, and the left condyle was used as a control. Two positional screws were used for rigid internal fixation of the fracture. von Mises stress distributions in the condyles and screws were analyzed. RESULTS: The von Mises stress generated in parasymphyseal trauma simulation showed a significant concentration in the sagittal direction of the condyle. In two-positional-screw osteosynthesis of the condylar head fractures, stress concentration appeared within the screws in the gap area between the two fractured segments and the area around the screw head. A small amount of stress was distributed in the screw holes and on the posterior surfaces of both segments. The von Mises stress was negligible in the fractured sagittal surfaces. CONCLUSION: It is reasonable to attribute the cause of type B condylar head fracture to the anatomical features of the condyle. The biomechanics of two-positional-screw osteosynthesis revealed that the stress can transmit through the screws to the medial fragments, and the stresses on both sagittal fractured surfaces are minimal.

The effect of meniscal tears and resultant partial meniscectomies on the knee contact stresses: a finite element analysis.

Knee osteoarthritis (OA) is believed to result from high levels of contact stresses on the articular cartilage and meniscus after meniscal damage. This study investigated the effect of meniscal tears and partial meniscectomies on the peak compressive and shear stresses in the human knee joint. An elaborate three-dimensional finite element model of knee joint including bones, articular cartilages, menisci and main ligaments was developed from computed tomography and magnetic resonance imaging images. This model was used to model four types of meniscal tears and their resultant partial meniscectomies and analysed under an axial 1150 N load at 0° flexion. Three different conditions were compared: a healthy knee joint, a knee joint with medial meniscal tears and a knee joint following partial meniscectomies. The numerical results showed that each meniscal tear and its resultant partial meniscectomy led to an increase in the peak compressive and shear stresses on the articular cartilages and meniscus in the medial knee compartment, especially for partial meniscectomy. Among the four types of meniscal tears, the oblique tear resulted in the highest values of the peak compressive and shear stresses. For the four partial meniscectomies, longitudinal meniscectomy led to the largest increase in these two stresses. The lateral compartment was minimally affected by all the simulations. The results of this study demonstrate meniscal tear and its resultant partial meniscectomy has a positive impact on the maintenance of high levels of contact stresses, which may improve the progression of knee OA, especially for partial meniscectomy. Surgeons should adopt a prudent strategy to preserve the greatest amount of meniscus possible.

A novel method to determine the potential rotational axis of the mandible during virtual three-dimensional orthognathic surgery.

During virtual three-dimensional orthognathic surgery in cases where an overlap or penetrability occurs between the 2 jaws due to the repositioning of the maxillary segment, it is necessary to establish a vertical opening of the mandible to obtain a relatively good relationship with the maxillary segment for the fabrication of an intermediate occlusal splint. However, there are few reports that address the precise definition of the rotational axis of the mandible during virtual surgery. Here, we present the idea that the mandible's movement during virtual three-dimensional orthognathic surgery is similar to hinge movement in vivo and developed a method for locating the geometric center of the three-dimensional condyle using Hypermesh software combined with Mimics software. Subsequently, we defined the rotational axis of the mandible based on the located geometric centers of the bilateral condyles, and the mandible was then rotated around the defined axis from the retruded contact position to mimic the hinge movement. Preliminary results indicated that the presented method could approximately mimic the hinge movement of the mandible with a relatively high accuracy in a three-dimensional environment, which may improve the accuracy of virtual intermediate occlusal splint.

Moving the mandible to the retruded contact position for simulating the hinge movement in virtual three-dimensional orthognathic surgery by integrating the plaster models.

The range of rotation of the mandible during virtual three-dimensional orthognathic surgery is small and may be similar to the hinge movement of the mandible. This current study offers a new method to move the mandible to the retruded contact position (RCP), a position of beginning hinge movement, during virtual three-dimensional orthognathic surgery. During this method, a three-dimensional skull model was reconstructed from the computed tomographic images in the Mimics software. Then the RCP in the patient could be obtained using Gothic arch tracer or swallowing method and was recorded using a wax plate, followed by transferring to plaster models. Subsequently, the plaster models in RCP were scanned using a dental surface scanner and imported into the Mimics software. Finally, we could move the mandible to the RCP based on the registration between the three-dimensional skull model and plaster model for simulating the hinge movement during virtual three-dimensional orthognathic surgery. This may be a small step forward for improving the accuracy of virtual three-dimensional orthognathic surgery.

Qing Hua Chang Yin exerts therapeutic effects against ulcerative colitis through the inhibition of the TLR4/NF-κB pathway.

The activation of the Toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) pathway has been implicated as a key mediator in the pathogenesis of ulcerative colitis (UC); therefore, it has become an attractive target for the treatment of UC. Qing Hua Chang Yin (QHCY) is a traditional Chinese formula, which has been used for many years to clinically treat conditions associated with inflammatory bowel diseases, such as UC. However, the precise mechanisms behind its anti-inflammatory effects remain largely unknown. In this study, using the dextran sulfate sodium (DSS)-induced colitis mouse model, we evaluated the therapeutic effects of QHCY against UC and elucidated the possible underlying molecular mechanisms. We found that the administration of QHCY profoundly ameliorated DSS-induced clinical manifestations, colon shortening and histological damage in the mice with colitis. In addition, treatment with QHCY significantly decreased the DSS-induced secretion of serum amylase. Moreover, QHCY significantly inhibited the DSS-induced expression of TLR4 and myeloid differentiation primary response gene 88 (MyD88), the phosphorylation of IκB and the nuclear translocation of NF-κB. Taken together, our findings suggest that the suppression of the TLR4/NF-κB signaling pathway may be one of the mechanisms involved in the therapeutic effects of QHCY against UC.

Three-dimensional reconstruction of subject-specific knee joint using computed tomography and magnetic resonance imaging image data fusions.

Three-dimensional reconstruction of human body from a living subject can be considered as the first step toward promoting virtual human project as a tool in clinical applications. This study proposes a detailed protocol for building subject-specific three-dimensional model of knee joint from a living subject. The computed tomography and magnetic resonance imaging image data of knee joint were used to reconstruct knee structures, including bones, skin, muscles, cartilages, menisci, and ligaments. They were fused to assemble the complete three-dimensional knee joint. The procedure was repeated three times with respect to three different methods of reference landmarks. The accuracy of image fusion in accordance with different landmarks was evaluated and compared with each other. The complete three-dimensional knee joint, which included 21 knee structures, was accurately developed. The choice of external or anatomical landmarks was not crucial to improve image fusion accuracy for three-dimensional reconstruction. Further work needs to be done to explore the value of the reconstructed three-dimensional knee joint for its biomechanics and kinematics.

Material assignment in finite element modeling: heterogeneous properties of the mandibular bone.

PURPOSE: The properties of the biomaterial are normally characterized by heterogeneity on all scales influencing the function and biomechanics. Elastic modulus (EM), which is one of the most important mechanical properties of material, is necessary for finite element modeling and needed to be determined by some methods. The aim of this study is to demonstrate the feasibility of assessment of EM from GrayValue (GV) of computed tomographic image and assignment of material properties in heterogeneous finite element modeling for studying the performance of the mandibular bones. METHODS: Three mandibles obtained from fresh human cadavers were used in this study. All mandibular bones were scanned using computed tomography, and the original data were stored in optical disks. The finite element modeling of the 3 mandibles was meshed using Materialise Mimics 10.01 and Abaqus 6.10 software. Using the empirical expression on relationship between GV and EM, the empirical EM of the meshed mandibular elements were calculated. To verify the empirical EM, actual EM of the three was determined by nanoindentation test using Oliver and Pharr method. The dependence of EM on test regions and loading directions were also discussed. RESULTS: The empirical EM of the mandible element is in the range of 3.7 to 23.4 Gpa, and EM of the cortical element is in the range of 8.6 to 13.6 Gpa. In comparison, the actual EM of cortical bone tested by nanoindentation method is in the range of 10.0 to 22.0 Gpa. The tested EM is varied with the test regions and loading directions. The difference in the values of EM determined by the empirical analysis and by the nanoindentation test is approximately 5.0 Gpa. CONCLUSIONS: A mandibular finite element model with heterogeneous material properties is built. By analyzing the EM value of this model, it is concluded that the actual EM in anterior-posterior direction in mandibular ramus and EM in superior-inferior direction in mandibular body match the empirical EM better than the other directions.

CBCT combining with plaster models: application in virtual three-dimensional subapical segmental osteotomy to obtain more precise occlusal splint.

Anterior subapical segmental osteotomy is considered to be an important surgical technique to obtain functional occlusion and improve the facial profile for patients with maxillary and mandibular protrusion or retrusion, and some complications, such as ischemic necrosis of the distal segment, devitalization of the teeth adjacent to the osteotomy site, and inadequate movement space of segment for obtaining a good occlusion or facial profile, usually exist during surgery. Imprecise measurement of root length, interradicular distance, and intertooth distance based on traditional panoramic radiography that demonstrated existing horizontal distortion and vertical distortion may play an important role in resulting in these problems. In addition, the root is invisible for surgical simulation in traditional plaster models. The recently developed cone-beam computed tomography (CBCT) presents a higher spatial resolution with a lower radiation dose, simultaneously with excellent accuracy and without magnification of images. The presented technique was used to obtain a precise occlusal splint in virtual 3D subapical segmental osteotomy by combining CBCT with plaster models that could guarantee the measurement accuracy of root length, interradicular distance, and intertooth distance, followed by the result of fewer tooth root damage and more precise forecasting of available movement space of jaw segment. Combining with other advantages of virtual 3D surgery, such as precise teeth surface of plaster models, soft tissue simulation, genoplasty simulation, and zygoma plasty simulation, this presented technique may offer a preferable method to patients who need subapical segmental osteotomy.

Three-dimensional reconstruction of extremity tumor regions by CT and MRI image data fusion for subject-specific preoperative assessment and planning.

This study was conducted to demonstrate the feasibility of three-dimensional (3D) reconstruction of extremity tumor regions for patient-specific preoperative assessment and planning by using CT and MRI image data fusion. The CT and MRI image data of five patients with solid tumors were fused to construct 3D models of the respective tumor regions. The reconstruction time and image fusion accuracy were measured, and the tumor features and spatial relationships were analyzed to enable subject-specific preoperative assessment and planning as guidance for tumor resection. The 3D models of the tumor regions, including skin, fat, bones, tumor, muscles, internal organs, nerves and vessels, were created with a mean reconstruction time of 103 minutes and fusion accuracy of 2.02 mm. The 3D reconstruction clearly delineated the tumor features, and provided a vivid view of spatial relationships within the tumor region. Based on this intuitional information, the subject-specific preoperative assessment and planning were easily accomplished, and all tumor resections were performed as planned preoperatively. Three-dimensional reconstruction using CT/MRI image fusion is feasible for accurate reproduction of the complex anatomy of the tumor region with high efficiency, and can help surgeons improve the preoperative assessment and planning for effective removal of tumors.

[Computational-fluid-dynamical analysis of the flow field of forearm flap with four types of venous anastomotic techniques].

PURPOSE: Using the computational fluid dynamics to analyse the alteration of flow field of free forearm flap with 4 different venous anastomotic techniques, and to preliminarily explore its clinical significance. METHODS: Three dimensional geometric models of radial forearm flap with 4 types of anastomotic techniques between radial vein and recipient vessels were established by Pro/E (Wildfire 4.0) as follow: type I(matched anastomosis), type II(stump anastomosis), type III (angular anastomosis) and type IV(end-to-side anastomosis). Then the established geometric models were transferred to the SC/Tetra 8.0 software for mesh generation and calculation. Porous model was applied to the flap to simulate capillary structure as before, inlet velocity of radial artery was set as 20mm/s and outlet pressure of recipient vein as 0 Pa. By comparing pressure and velocity distribution on different cross sections of blood vessels, hemodynamic feature of the flap with 4 types of anastomotic techniques was studied, focusing on the alternation of flow field of drainage system of the flap, especially at the anastomotic sites. The data was analysed using SAS8.0 software package for ANOVA. RESULTS: The pressure on the four sections of the flap circulatory system was significantly higher in type I compared with type II, III and IV (F=40.99,P<0.001). Type II presented with vortex in the anastomotic site, and type III,IV with smooth flow. Type IV had an absorption effect at the anastomotic site. The pressure loss of the flap circulation was maximal in the radial vein of vascular pedicle(F=97.00,P<0.001). CONCLUSIONS: Type III and IV are considered appropriate techniques to deal with caliber discrepancy of recipient site. Theoretically, reasonable reduction of the vascular pedicle length and choice of the concomitant radial vein with wider radius for anastomosis can effectively decrease the resistance of circulation in the flap.

[Establishment of hemodynamic model of human radial forearm free flap].

PURPOSE: To preliminarily establish a hemodynamic 3D numeric model of radial forearm free flap with vascular pedicle of radial artery and vein, and discuss its scientific workability. METHODS: The 3D geometric model of 50mm×80mm×10mm radial forearm flap was established by Pro/E(Wildfire 4.0). The vascular pedicle was 50mm in length including radial artery (inside diameter was 1.9mm) and concomitant radial vein (inside diameter was 0.84mm). The half-embedded vessels went hrough the flap paralleling the long axis. Then the established geometric model was transferred to the SC/Tetra 8.0 software for mesh generation and calculation. According to the virtual flow volume of the radial artery, the inlet velocity was set as 20mm/s. With the different blood pressure of 53mmHg between the feeding artery and draining vein, the tentative porous values were achieved. Then porous model was applied to the flap to simulate the capillary structure. The pressure distribution on the central axis of radial artery and vein and the radial velocity distribution in three different cross sections of vessels were figured out. RESULTS: A model with 10355473 meshes and 2104014 nodes was built. When porous model was applied, the pressure difference between radial artery and vein was calculated to 7050 Pa (52.8mmHg), which was close to clinical value. The computational fluid dynamic analysis results showed that with porous model, the central pressure of radial artery was continuously kept to a higher level. When blood flowed in and flows out of the flap, the blood velocity decreased and increased greatly. While the central pressure of radial vein significantly decreased at the moment of blood flowing out of the flap. These results basically agreed with the features of normal blood circulation of the forearm flap. CONCLUSIONS: Porous model effectively simulates hemodynamic status of forearm flap, which provides a new method for the study of mechanism of blood circulation in radial forearm flap and also lays a foundation for the following hemodynamic study of vascular anastomosis.