The lumbar intervertebral disc exhibits a complex physiological structure with interactions between various segments, and its components are extremely complex. The material properties of different components in the lumbar intervertebral disc, especially the water content (undergoing dynamic change as influenced by age, degeneration, mechanical loading, and proteoglycan content) - critically determine its mechanical properties. When the lumbar intervertebral disc is under continuous pressure, water seeps out, and after the pressure is removed, water re-infiltrates. This dynamic fluid exchange process directly affects the mechanical properties of the lumbar intervertebral disc, while previous isotropic modeling methods have been unable to accurately reflect such solid-liquid phase behaviors. To explore the load-bearing mechanism of the lumbar intervertebral disc and establish a more realistic mechanical model of the lumbar intervertebral disc, this study developed a solid-liquid biphasic, fiber-reinforced finite element model. This model was used to simulate the four movements of the human lumbar spine in daily life, namely flexion, extension, axial rotation, and lateral bending. The fluid pressure, effective solid stress, and liquid pressure-bearing ratio of the annulus fibrosus and nucleus pulposus of different lumbar intervertebral discs were compared and analyzed under the movements. Under all the movements, the fluid pressure distribution was closer to the nucleus pulposus, while the effective solid stress distribution was more concentrated in the outer annulus fibrosus. In terms of fluid pressure, the maximum fluid pressure of the lumbar intervertebral disc during lateral bending was 1.95 MPa, significantly higher than the maximum fluid pressure under other movements. Meanwhile, the maximum effective solid stress of the lumbar intervertebral disc during flexion was 2.43 MPa, markedly higher than the maximum effective solid stress under other movements. Overall, the liquid pressure-bearing ratio under axial rotation was smaller than that under other movements. Based on the solid-liquid biphasic modeling method, this study more accurately revealed the dominant role of the liquid phase in the daily load-bearing process of the lumbar intervertebral disc and the solid-phase mechanical mechanism of the annulus fibrosus load-bearing, and more effectively predicted the solid-liquid phase co-load-bearing mechanism of the lumbar intervertebral disc in daily life.
Humans ; Finite Element Analysis ; Intervertebral Disc/physiology* ; Lumbar Vertebrae/physiology* ; Weight-Bearing/physiology* ; Biomechanical Phenomena ; Stress, Mechanical ; Computer Simulation ; Models, Biological

BACKGROUND:Avascular necrosis of the femoral head is a refractory orthopedic disease that seriously affects the normal life of patients.Hip preservation is recommended for young patients due to the limited prosthesis longevity and revision.Accurate prediction of the mechanical properties of the necrotic area in the early stage and then intervention is the key to hip preservation. OBJECTIVE:To establish a dynamic contact mechanics finite element model of necrotic femoral head based on human hip CT data and predict effects of both necrotic volume magnitude and its position on biomechanics of the necrotic region under walking movement. METHODS:CT data of a volunteer were collected and then geometry model of the hip was rebuilt.Finite element model of the necrotic femoral head was established using the Abaqus software.Nine different necrotic femoral models were constructed by combined both three different necrotic volume magnitudes(small,medium and big volume)and three different necrotic positions(coincided with,medium deviated with and kept away from the line of the force).The Von Mises of the necrotic region for all models were predicted under both 3 000 N static load and dynamical loads of one whole ISO walking gait cycle.The collapse risk for all models was evaluated based on collapse criterion. RESULTS AND CONCLUSION:(1)More approaching of the necrotic region to the line of force and bigger collapse volume made the maximum Von Mises increasing.This also enlarged the collapse risk of the necrotic region.(2)For different load types,walking movement increased the maximum Von Mises of the necrotic region than that of the value under static load under the same necrotic volume and location.(3)In conclusion,dynamic load would result in increasing of the maximum Von Mises of the necrotic region comparing to static load during exercise.Therefore,the risk of local collapse will increase due to greater Von Mises.However,the overall collapse risk is lower than that of static load due to the dynamic change of bearing area.This factor should be carefully considered by surgeons when they evaluate the mechanical performance of the necrotic femoral head.

Objective:To evaluate the mechanical performance of customized metal prosthesis with tibia stems of varying lengths for tibial bone defects reconstruction.Methods:Morphologically matched postoperative finite element models of bone defect revision were developed, with three gradients (15 mm, 30 mm, and 45 mm) according to the degree of bone defect and were reconstructed with 3D printed tantalum metal prosthesis using three tibial stem lengths (80 mm, 120 mm, and 150 mm), respectively. Conventional static and dynamic (walking gait) loading was performed to analyze the peak tibial stress distribution and accumulated sliding distance at the prosthetic interface, and to assess the effects of the three tibial stems of different lengths on the stability of the customized tibial defect restorations and the internal tibial stress state.Results:The peak accumulated sliding distance of the dynamically loaded morphologically matched restorations ranged from 17.94 to 21.31 mm with static loading, which were 68% to 84.3% higher than those of 10.26 to 11.69 mm with static loading. The peak tibial stresses in the dynamically loaded model were greater than those in the statically loaded model, with an increase of 28%-49.2%, including 132.94-143.88 MPa in the statically loaded model and 170.41-200.14 MPa in the dynamically loaded model. The overall accumulated sliding distance of the tibia prosthetic model gradually decreased from the tibial osteotomy surface, and the accumulated peak sliding distances ranged from 10.26 to 11.69 mm for static loading, and from 17.94 to 21.31 mm for dynamic loading. The bone tissue stresses in the anterolateral and medial-posterior tibia increased gradually from top to bottom, and the maximum stress value in each section was in the posterior medial tibia (the maximum value was 200.14 MPa). The highest bone tissue stress in the lateral tibia was affected by the tibial stem length, which resulted in a different location, and it was the area most affected by stress shielding (maximum value of 170.65 MPa).Conclusion:For stability assessment of morphologically matched tantalum customized prosthesis, physiological gait dynamic loading studies are more reliable than static loading; the choice of tibial stem length depends on a combination of accumulated peak sliding distances and tibial bone stress distribution factors.

Objective To study the effect of fine particulate matter(particulate matter 2.5,PM2.5)exposure on hepatic lymphangiogenesis in C57BL/6J mice and metabolic-associated fatty liver disease(MAFLD)model mice,and to provide a novel target for prevention and treatment of PM2.5-induced liver injury.Methods Forty male C57BL/6J mice were randomly divided into a control group,PM2.5 group,MAFLD group,and PM2.5-MAFLD group.Mice in the MAFLD and PM2.5-MAFLD groups were fed high-fat diet for 12 weeks,and mice in the other groups were fed normal chow diet.From weeks 13 to 16,mice in the PM2.5 and PM2.5-MAFLD groups were exposed to PM2.5 by tracheal instillation(twice per week),and mice in the other groups were instilled with saline at the same time.All animals were euthanized 24 h after the last PM2.5 instillation.Serum alanine aminotransferase(ALT)and aspartate aminotransferase(AST)were measured,and the expression of LYVE1 in liver tissues was visualized using immunofluorescence staining.Hepatic oxidative stress markers levels(4-HNE and GSH/GSSG)were measured.The protein expression levels of lymphangiogenesis markers(PROX1 and LYVE1),lymphangiogenesis regulatory protein VEGF-C,and the lymphatic junctional function marker VE-cadherin in liver tissue were determined using Western Blot.Results PM2.5 exposure significantly increased the levels of serum AST and ALT,markedly decreased the protein expression of PROX1 and LYVE1,increased the protein expression of VEGF-C and VE-cadherin in the liver,increased the level of 4-HNE,and decreased the T-GSH/GSSG ratio in livers of mice in the MAFLD group(P＜0.05).However,PM2.5 exposure did not affect the levels of serum AST and ALT,protein expression of PROX1,LYVE1,or VEGF-C;level of 4-HNE;or T-GSH/GSSG ratio in the livers of the C57BL/6J mice(P＞0.05).Conclusions PM2.5 exposure obviously aggravated hepatic oxidative injury and reduced hepatic lymphangiogenesis by reducing the VEGF-C concentration in the livers of MAFLD model mice.

Temporomandibular joint (TMJ) diseases are common clinical conditions. The number of patients with TMJ diseases is large, and the etiology, epidemiology, disease spectrum, and treatment of the disease remain controversial and unknown. To understand and master the current situation of the occurrence, development and prevention of TMJ diseases, as well as to identify the patterns in etiology, incidence, drug sensitivity, and prognosis is crucial for alleviating patients′suffering.This will facilitate in-depth medical research, effective disease prevention measures, and the formulation of corresponding health policies. Cohort construction and research has an irreplaceable role in precise disease prevention and significant improvement in diagnosis and treatment levels. Large-scale cohort studies are needed to explore the relationship between potential risk factors and outcomes of TMJ diseases, and to observe disease prognoses through long-term follw-ups. The consensus aims to establish a standard conceptual frame work for a cohort study on patients with TMJ disease while providing ideas for cohort data standards to this condition. TMJ disease cohort data consists of both common data standards applicable to all specific disease cohorts as well as disease-specific data standards. Common data were available for each specific disease cohort. By integrating different cohort research resources, standard problems or study variables can be unified. Long-term follow-up can be performed using consistent definitions and criteria across different projects for better core data collection. It is hoped that this consensus will be facilitate the development cohort studies of TMJ diseases.

Objective:To investigate the effects of intra-articular injection of exosomes derived from dental pulp stem cells from hu-man exfoliated deciduous teeth(SHED-EXO)on subchondral bone homeostasis in rat temporomandibular joint osteoarthritis(TMJ OA)process.Methods:36 male SD rats were randomly divided into 3 groups(n=12):control(CON),sodium iodoacetate(MIA)-induced TMJ OA(MIA),and SHED-EXO injection into TMJ OA(SHED-EXO)groups.At 2 and 6 weeks post-treatment,Micro-CT,Double labeling,TRAP staining,and immunohistochemical staining were employed to detect osteoclasts and osteoblasts in the subchondral bone.Additionally,the mRNA expression levels of ADAMTs5,IL-1β,OCN and OPG/RANKL were analyzed by qRT-PCR.Results:The MIA group exhibited significant bone loss and an enlarged bone marrow cavity.In comparison with the CON group,BV/TV and Tb.Th were lower(P＜0.001),while BS/BV,Tb.Sp,and Tb.N were higher(P＜0.01).Additionally,the bone formation rate within 5 days was low-er than that of the control group(P＜0.001).When compared to the MIA group,the SHED-EXO group showed a significant increase in bone morphology and bone mass.BV/TV and Tb.Th were increased(P＜0.01),while BS/BV,Tb.Sp and Tb.N were decreased(P＜0.05).The bone formation rate was higher(P＜0.01).Compared with both the control and treatment groups,the MIA group exhibited a significant increase in the number of osteoclasts in the subchondral bone(P＜0.01),along with a notable decrease in H-type blood vessels and OCN-positive areas(P＜0.01).Conclusion:Intra-articular injection of SHED-EXO can reg-ulate condylar subchondral bone homeostasis in TMJ OA of rats by promoting osteogenesis and inhibiting osteoclasts.

Objective: To explore the biological effects of electromagnetic pulse (EMP) with different high intensities on condylar cartilage in rats. Methods: SD rats were randomly divided into a sham group (Sham) and an irradiation group (EMP1: 500 kV/m, 10 Hz; EMP2: 270 kV/m, 10 Hz). Then, they were sacrificed at 1 h, 3 h, 12 h, 24 h and 3 d after irradiation. The degree of cartilage degeneration was evaluated by HE, safranine O-fast green, type Ⅱ collagen immunohistochemistry and TUNEL staining. Immunohistochemistry and western blot were performed to detect the expression of the matrix degradation factors: matrix metalloproteinase-13 (MMP-13), a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS-5) and the apoptosis key factor cleaved-cysteinyl aspartate specific proteinase (cleaved-Caspase3) in condylar cartilage. Results : HE staining showed that, compared with the Sham group, a small amount of exfoliation was found on the fibrous surface layer of the cartilage after irradiation in the EMP1 and EMP2 groups. Compared with the Sham group, the percentage of safranine O-fast green-positive area decreased significantly at 12 h and 24 h (both P<0.01) in the EMP1 group and 12 h and 24 h in the EMP2 group (both P<0.05); the percentage of type Ⅱ collagen-positive area decreased significantly at 3 h and 12 h (P<0.05, P<0.001) in the EMP1 group. In addition, the number of TUNEL-positive apoptotic cells increased significantly at 1 h, 3 h, 12 h, and 24 h in the EMP1 group and 1 h, 3 h, and 12 h in the EMP2 group (P<0.05). Moreover, at different timepoints (except at 3 d) in the EMP1 group and EMP2 group, the percentage of MMP-13, ADAMTS-5- and cleaved Caspase3-positive chondrocytes and their protein levels in condylar cartilage increased significantly after irradiation (P<0.05). Conclusion EMP with a certain degree of high-intensity can induce early transient damage to condylar cartilage. This effect is dose-and time-dependent.

Objective:To investigate the clinical efficacy of microscopic myringoplasty versus endoscopic myringoplasty in the treatment of tympanic membrane perforation caused by chronic suppurative otitis media. Methods:The clinical data of 91 patients with tympanic membrane perforation caused by chronic suppurative otitis media who received treatment in Jiaxing Second Hospital, China between February 2017 and March 2019 were retrospectively analyzed. These patients were divided into a control group ( n = 45) and an observation group ( n = 46) according to different surgery methods. The control group was given microscopic tympanoplasty, while the observation group was given endoscopic tympanoplasty under the otoendoscope. Results:Blood loss in the observation group was significantly lower than that in the control group [(7.2 ± 2.0) mL vs. (13.7 ± 3.1) mL, t = 11.912, P < 0.001]. Operation time in the observation group was significantly shorter than that in the control group [(59.4 ± 5.4) min vs. (91.5 ± 11.2) min, t = 17.474, P < 0.001]. Postoperative pain score in the observation group was significantly lower than that in the control group [(2.9 ± 0.7) points vs. (4.8 ± 1.3) points, t = 8.707, P < 0.001]. Hospital stay in the observation group was significantly shorter than that in the control group [(4.3 ± 1.0) d vs. (6.5 ± 1.5) d, t = 8.249, P < 0.001]. Pure tone hearing thresholds at 1, 2 and 4 kHz frequencies in the observation group were significantly higher than those in the control group (all P < 0.05). Patient satisfaction regarding the aesthetic effect of the surgical incision in the observation group was significantly higher than that in the control group [97.8% (45/46) vs. 77.8% (35/45), χ2 = 8.604, P = 0.003]. Conclusion:Endoscopic myringoplasty has the advantages including shorter operation time, less blood loss, lower degree of pain, better hearing improvement and higher patient satisfaction over microscopic myringoplasty in the treatment of tympanic membrane perforation caused by chronic suppurative otitis media.

Objective: To explore the improvement rate of liver fibrosis in patients with chronic hepatitis B virus infection who received entecavir alone or in combination with anluohuaxianwan for 78 weeks. Methods: Patients with chronic HBV infection were randomly treated with entecavir alone or in combination with anluohuaxian for 78 weeks. Ishak fibrosis score was used for blind interpretation of liver biopsy specimens. The improvement in liver fibrosis condition before and after the treatment was compared. Student's t test and non-parametric test (Mann-Whitney U-Test and Kruskal-Wallis test) were used to analyze the measurement data. The categorical variables were analyzed by Chi-square test method and Spearman’s rank correlation coefficient was used to test bivariate associations. Results: Liver fibrosis improvement rate after 78 weeks of treatment was 36.53% (80/219) and the progression rate was 23.29% (51/219). The improvement of liver fibrosis was associated to the degree of baseline fibrosis and treatment methods (P < 0.05). The improvement rate of hepatic fibrosis in patients treated with anluohuaxianwan combined with entecavir at baseline F < 3 (54.74%, 52/95) was significantly higher than that in patients treated only with entecavir (33.33%, 16/48), P = 0.016 and the progression rate of hepatic fibrosis (13.68%, 13/95) was lower than that in patients treated alone (18.75%, 9/48), P = 0.466. In patients with baseline F < 3, the proportion of patients with improved and stable liver fibrosis in the combined treatment group (68.1%, 32/47) was higher than that in the treatment group alone (51.7%, 15/29). Conclusion Combined anluohuaxianwan and entecavir treatment can significantly improve the improvement rate of liver fibrosis in patients with chronic hepatitis B virus infection. Furthermore, it has the tendency to improve the stability rate and reduce the rate of progression of liver fibrosis.

Objective To evaluate systematically the efficacy of mirror therapy for improving the upper limb function, daily life and pain of stroke survivors. Methods The PubMed, EBSCO, Web of Science, Ovid, Co-chrane Library, Open Gray, China Biological Medicine, China National Knowledge Infrastructure, GoogleScholar, VIP and Wan Fang Data databases were searched for reports of randomized and controlled trials ( RCTs) of mirror therapy for improving the upper limb function of stroke survivors. Only papers published before December 2015 were surveyed. The relevant references of the primary studies were also searched. The literature screening, data extraction and assessments were conducted by two reviewers independently. The meta-analysis was performed using version 5.2 of the RevMan software. Results A total of 22 RCTs involving 823 patients were discovered, some not dealing with mirror therapy. Comparing the studies with and without visual feedback, there were significant differences in upper limb motor function as measured by the Fugl-Meyer, ARAT and Brunnstrom instruments. The average Barthel indexes and visual analogue scale were also significantly different. Conclusion Mirror therapy can improve upper limb function and ability in the activities of daily living, and also relieve pain among stroke survivors to some degree, though its long-term efficacy is still unclear. Large-sample, multi-center, high-quality RCTs are required to verify these conclusions.