[Progress in minimally invasive surgery for adjacent segment disease after lumbar fusion].

Adjacent segment disease (ASDis) is a common complication of posterior lumbar spine fusion and often requires surgical treatment. In the treatment of ASDis, percutaneous spinal endoscopy can be used for simple decompression without removal of the original internal fixation, or for posterior fixation and fusion under the scope or in combination with other access fixation and fusion techniques, with the advantages of less surgical trauma, less bleeding, and faster postoperative recovery. Traditional trajectory screw technique is one of the risk factors for adjacent segment degeneration because of its tendency to cause damage to the adjacent synovial joint during surgery. In contrast, the cortical tone trajectory (CBT) screw placement technique not only reduces the damage to the articular joint during the screw placement process, but also preserves the original internal fixation in the treatment of ASDis, which significantly reduces the surgical trauma. Secondly, the implantation of CBT screws with the aid of digital technologies such as three-dimentinal printed guides, CT navigation, and robotics allows for more precise "double nailing" of ASDis patients to complete the fusion of adjacent segments, and is a minimally invasive procedure to be considered for patients who meet the clinical indications for fusion. This article reviews the literature on the use of percutaneous spinal endoscopy and CBT in the surgical management of ASDis.

Combining thermal imaging and spectral pyrometry for express temperature mapping in additive manufacturing.

A compact and low-cost two-dimensional (2D) thermal imager was developed for real-time temperature mapping of a melt pool during coaxial laser cladding (the additive manufacturing technique). The device combines a color CMOS camera and a compact spectrometer. The spectrometer was utilized for internal calibration and validation of a 2D temperature map that was acquired by the CMOS camera. The remarkable feature of the thermal imager is that camera images are calibrated directly during the measurement process utilizing spectral pyrometry. Additionally, the spectrometer decreased a potential systematic error due to a spectrum contribution from atomic/ionic lines emission. The spectral pyrometry provided temperature accuracy measurements of ±23K while two-dimensional (2D) temperature mapping by two-color pyrometry accuracy was estimated as ±38K in the range of 1700-3500 K. The system has been installed at a coaxial laser cladding head for real-time temperature mapping. The system was developed for measuring a melt pool during laser cladding production of a high wear-resistant coating (tungsten carbide particles in a nickel matrix). Tungsten carbides powder flow rate has been changed sequentially from 5 to 27 g/min by powder feeder programming, which resulted in a variation of melt pool dimensions and temperature maps during the cladding process.

[Clinical characteristics and outcome analysis of COVID-19 patients with pulmonary tuberculosis].

Coronavirus disease (COVID-19) and tuberculosis (TB) are two respiratory infectious diseases with a high incidence of transmission, mainly via respiratory droplets and both can weaken the immune system and lower the number of CD4+T cells in patients. COVID-19 can occur before, at the same time or after the diagnosis of TB. Patients with pulmonary TB are more likely to have co-infection when they have a history of epidemiological exposure to COVID-19. At present, many cases of nosocomial infection of COVID-19 caused by ineffective prevention and control measures in tuberculosis hospitals have been reported successively at domestic and overseas. Therefore, it is urgent to strengthen the prevention and control of nosocomial infections in tuberculosis hospitals. The superposition of the two diseases can lead to a worsening prognosis, aggravating the patient's condition and making treatment more difficult. In addition, in the context of the new coronavirus epidemic, early recognition of co-infection with new coronavirus should be made when TB patients in chest hospitals present with symptoms such as aggregated fever or progressive disease. At the same time, we should focus on identifying the clinical and imaging manifestations of TB and COVID-19 co-infection. At present, research on COVID-19 complicated with pulmonary TB is scarce, and there are disputes on many aspects. As a country with a high prevalence of tuberculosis, it is of great practical significance to identify the clinical characteristics, outcomes, and treatment of the two infectious diseases in China.

Rehabilitation training improves cognitive disorder after cerebrovascular accident by improving BDNF Bcl-2 and Bax expressions in regulating the JMK pathway.

OBJECTIVE: To explore the effect of rehabilitation training on cognitive impairment after cerebrovascular accident and its potential mechanism. PATIENTS AND METHODS: 100 patients of cerebrovascular accident treated in our hospital from August 2018 to August 2019 were selected as the subjects, and 50 patients with physical examination were selected as healthy control group. The patients with cerebrovascular accident were randomly divided into control group (50 patients) and research group (50 patients). The patients in the control group were given routine medication, the patients in research group were given rehabilitation training on the basis of routine drug therapy. The blood samples were collected on admission and 6 months after admission to detect the molecular markers related to inflammation, nerve cell nutrition and function and apoptosis in the serum. The cognitive function was evaluated by scales. We established a rat cerebral ischemia model, compared the differences in the evasive latency, serum CRP, BNDF, Bcl-2, BAX, Glu, NE levels and BNDF, TrkB, pTrkB, JNK levels in hippocampus, amygdala, and prefrontal tissue between model rats after rehabilitation training and model rats without rehabilitation training. RESULTS: On admission, there were no significant differences in the scores of Barthel index (BI), Fugl-Meyer motor function scale (FM), Montreal cognitive assessment scale (MoCA) and mini-mental state examination (MMSE) (p>0.05). 6 months later, the above scores and BNDF, Bcl-2, and norepinephrine were significantly higher in the research group (p<0.05), while CRP, Bax, 5-HT and glutamate in the research group were significantly lower than those in the control group (p<0.05). CONCLUSIONS: Rehabilitation training can improve the motor function, mental state and cognitive level of patients, reduce the levels of neurotoxic factors, pro-inflammatory factors and pro-apoptotic factors, and improve the levels of inhibiting apoptotic factors, neurotrophic factors and neurotransmitters. In animal experiments, rehabilitation training can increase BDNF and its activated receptors in hippocampus, amygdala and prefrontal lobe of rats, and decrease JNK of apoptotic protein, suggesting that rehabilitation training may regulate the expression of apoptotic proteins Bcl-2 and Bax by upregulating BDNF and its receptors and acting on JNK pathway, thereby inhibiting cell apoptosis and improving cognitive impairment after cerebrovascular accident.

[Problem of the carbon dioxide embolism during the procedure of transanal total mesorectal excision].

Carbon dioxide embolization is a special complication of laparoscopic colorectal surgery. It is rarely reported in conventional laparoscopic colorectal surgery, and has not been well recognized by surgeons. Transanal total mesorectal excision (taTME) is an increasingly popular sphincter-preserving surgery for low rectal cancer in recent years. Although the number of cases worldwide is not large, carbon dioxide embolization after operation has been reported successively. Once serious carbon dioxide embolization occurs, the mortality is extremely high. The main related factors of carbon dioxide embolization in taTME include high pressure of pneumoperitoneum, narrow space, abundant blood supply of prostate and vaginal wall, Trendelenburg position, etc. The key of prevention and treatment is to pay attention to the control of related risk factors, identify the early signs of carbon dioxide embolism, and take active and effective symptomatic treatment. Reducing the pressure of pneumoperitoneum perfusion can reduce the occurrence of CO2 embolism. Transesophageal echocardiography is the most sensitive way to monitor intravenously CO2, but it is difficult to carry out in clinical practice. The sudden decrease of end expiratory CO2 partial pressure is an important sign of early detection of CO2 embolism. If there is a suspicious lacuna in the operation, it is possible to reduce or stop the pneumoperitoneum when it is unable to distinguish between normal tissue gap or vascular lumen. If the "bubble sign" is observed, CO2 may enter the vein. The risk of venous embolism should be considered.

[A comparison of fine needle nonaspiration cytology versus fine needle aspiration for thyroid nodules: a Meta-analysis].

Objective:To evaluate the differences of smear quality and diagnostic accuracy between thyroid nodules and fine needle nonaspiration cytology (FNNAC) and fine needle aspiration cytology (FNAC).Method:Databases were used to search the literature on FNNAC and FNAC. All statistical analyses were performed using Review Manager 5.3 Software.Result:A total of 10 studies were included in the study. Meta-analysis showed no significant difference in FNNAC and FNAC between low, middle and high quality smears. There was no significant difference in diagnostic accuracy.Conclusion:There were no difference in obtaining the smear quality and diagnostic accuracy, the person doing the piercing can freely choose which way according to the habit.

Efficacy of radioiodine therapy for treating 20 patients with pulmonary metastases from differentiated thyroid cancer and a meta-analysis of the current literature.

BACKGROUND: Radioiodine therapy (RAI) after total or near-total thyroidectomy is a recommended treatment for patients with pulmonary metastasis from differentiated thyroid cancer (DTC). However, the total effective rate of iodine-131 therapy remains controversial. This study aimed to determine the efficacy of RAI for treating patients with pulmonary metastasis from DTC, and to identify independent predictors of its efficacy. METHODS: We conducted a retrospective study to evaluate 20 patients with pulmonary metastasis from DTC who underwent RAI at our center at first and performed a meta-analysis to evaluate relevant literature regarding the overall efficacy of RAI and subgroup-specific efficacies subsequently. RESULTS: The efficacy rate at our center was 40%, and no significant differences were observed according to sex, age, pathological type, metastasis state, or interval between the initial RAI and final surgery. The meta-analysis revealed that the pooled overall efficacy rate was 58%, and significant differences were observed when we compared pulmonary metastasis versus pulmonary and other distant metastasis, age of < 40 years versus age of ≥ 40 years, papillary thyroid cancer versus follicular thyroid cancer and male patients versus female patients. CONCLUSIONS: These results suggest that RAI is an effective treatment for patients with pulmonary metastasis from DTC after surgical treatment. The efficacy of RAI was significantly predicted by the presence of papillary thyroid cancer, age of < 40 years, the absence of non-lung distant metastasis and female patients.

Primary antibiotic resistance of Helicobacter pylori in Chinese patients: a multiregion prospective 7-year study.

OBJECTIVES: To explore the characteristics of Helicobacter pylori resistance in China and the association between antibiotic resistance and several clinical factors. METHODS: H. pylori strains were collected from patients in 13 provinces or cities in China between 2010 and 2016. Demographic data including type of disease, geographic area, age, gender and isolation year were collected to analyse their association with antibiotic resistance. Antibiotic resistance was detected using the Etest test and the Kirby-Bauer disc diffusion method. RESULTS: H. pylori were successfully cultured from 1117 patients. The prevalence of metronidazole, clarithromycin (CLA), azithromycin, levofloxacin (LEV), moxifloxacin, amoxicillin (AMO), tetracycline and rifampicin resistance was 78.2, 22.1, 23.3, 19.2, 17.2, 3.4, 1.9 and 1.5%, respectively. No resistance to furazolidone was observed. The resistance rates to LEV and moxifloxacin were higher in strains isolated from patients with gastritis compared to those with duodenal ulcer and among women. Compared to patients ≥40 years old, younger patients exhibited lower resistance rates to CLA, azithromycin, LEV and moxifloxacin. The resistance rates to CLA and AMO were higher in strains isolated more recently, and we also found that the prevalence of resistance to metronidazole, CLA, azithromycin and AMO were significantly different among different regions of China. CONCLUSIONS: The resistance rates to metronidazole, CLA and LEV were high in China. Patient age, gender, disease and location were associated with the resistance of H. pylori to some antibiotics. Furazolidone, AMO and tetracycline are better choices for H. pylori treatment in China.

[A cost-benefit analysis of occupational disease reporting in China].

Objective: To perform a cost-benefit analysis of the occupational disease reporting system in China, and to provide a basis for effective resource allocation. Methods: The data on the cost of occupational diseases were collected from China Health Statistics Yearbook 2013, the estimated benefit data were collected from published articles in China and foreign countries, and the probability data were collected from the occupational diseasereports published by health and family planning administrative departments. Adecision-making tree was used for the cost-benefit analysis. Results: The estimated cost of occupational disease reporting was about 102.47 million yuan/year, consisting of a cost of reporting in national medical institutions of 1.25 million yuan/year, a management cost of 30.35 million yuan/year, a management cost in local public health institutions of 69.80 million yuan/year, a management cost in national public health institutions of 370 thousand yuan/year, and a cost of construction and maintenance of reporting system of 700 thousand yuan/year. The results of the decision tree analysis showed that when an occupational disease monitoring system was established, the incremental input for occupational disease monitoring and prevention/control was 2.1 billion yuan/year, the output was 6.5 billion yuan/year, and the benefit of occupational disease reporting system was 4.4 billion yuan/year. Conclusion: The benefit of occupational disease reporting system depends on the cost-benefit of occupational disease prevention and control measures, and proper prevention and control measures are extremely important for improving the benefit of occupational disease reporting system.

Secalonic acid- F inhibited cell growth more effectively than 5-fluorouracil on hepatocellular carcinoma in vitro and in vivo.

Hepatocellular carcinoma (HCC), one of the most common types of liver cancer, could be treated with 5-fluorouracil (5-FU). Due to its side effects, 5-FU is more often used as the co-administration drug in clinical practice. Secalonic acid-F (SAF), isolated from a fungal strain identified in our lab as Aspergillus aculeatus, showed potent biological activities. The goal of this study was to evaluate the inhibitory effects of SAF on hepatocellular carcinoma and to compare it with that of 5-FU. Results showed that SAF effectively inhibited cell growth with a dose-dependent manner in vitro and in vivo. And the inhibitory effects of SAF were stronger than that of 5-FU. Importantly, the cytotoxicity of SAF to peripheral blood mononuclear cells (PBMC) was similar to that of 5-FU. Furthermore, this study demonstrated that SAF arrested the cell cycle at the G1 phase and induced apoptosis with a dose-dependent manner by activating caspase3 and caspase9 through a mitochondrial pathway. Consequently, SAF may be a better potential candidate compound for human cancer treatment; these results will afford more data for antitumor agent design in detail.

Risk factors for delayed gastric emptying following laparoscopic repair of very large hiatus hernias.

BACKGROUND: Delayed gastric emptying can complicate surgery for hiatus hernia. The aim of this study was to quantify its incidence following laparoscopic repair of very large hiatus hernias, identify key risk factors for its occurrence and determine its impact on clinical outcomes. METHODS: Data collected from a randomized trial of patients who underwent laparoscopic mesh versus sutured repair of very large hiatus hernias (more than 50 per cent of stomach in chest) were analysed retrospectively. Delayed gastric emptying was defined as endoscopic evidence of solid food in the stomach after fasting for 6 h at 6 months after surgery. RESULTS: Delayed gastric emptying occurred in 19 of 102 patients (18·6 per cent). In univariable analysis, type 2 paraoesophageal hernia (relative risk (RR) 3·15, 95 per cent c.i. 1·41 to 7·06), concurrent anterior and posterior hiatal repair (RR 2·66, 1·14 to 6·18), hernia sac excision (RR 4·85, 1·65 to 14·24), 270°/360° fundoplication (RR 3·64, 1·72 to 7·68), division of short gastric vessels (RR 6·82, 2·12 to 21·90) and revisional surgery (RR 3·69, 1·73 to 7·87) correlated with delayed gastric emptying. In multivariable analysis, division of short gastric vessels (RR 6·27, 1·85 to 21·26) and revisional surgery (RR 6·19, 1·32 to 28·96) were independently associated with delayed gastric emptying. Delayed gastric emptying correlated with adverse gastrointestinal symptomatology, including higher rates of bloating, nausea, vomiting and anorexia, as well as reduced patient satisfaction with the operation and recovery. CONCLUSION: Delayed gastric emptying following large hiatus hernia repair is common and associated with adverse symptoms and reduced patient satisfaction. Division of short gastric vessels and revisional surgery were independently associated with its occurrence.

[Diagnostic accuracy and safety of US-guided core needle biopsy versus fine needle aspiration biopsy of thyroid nodules: a Meta analysis].

Objective:To evaluate the efficacy and safety of core needle biopsy (CNB) and fine neon needle aspiration biopsy (FNAB) in the diagnosis of thyroid nodules.Method:The CNKI, Wanfang database, China Biomedical Literature Database (CBM), PubMed, Cochrane Library, EMBASE, Web of Science database (the deadline of February 2017) were used to search the literature on CNB and FNABCNB. Two reviewers independently screened the literature according to the inclusion and exclusion criteria, extracted the data and evaluated the quality of the literature, and used RevMan 5.3 software for Meta analysis.Result:The accuracy of the CNB group was higher than that of the FNAB group(RR= 1.14, 95%CI: 1.06-1.22, P< 0.01). Meta analysis showed that the accuracy of CNB group compared with FNAB group was statistically significant the difference was statistically significant. There was no significant difference between the two groups (RR= 0.92, 95%CI:0.67-1.25, P> 0.05).Conclusion:CNB is safe and feasible in the diagnosis of thyroid nodules under the condition of mastery of puncture technique.

[Therapeutic effect of IGF-1R-targeting inhibitor (TAE226) on malignant pleural effusion in nude mice].

OBJECTIVE: To study the therapeutic effect of IGF-1R inhibitor TAE226 on malignant pleural effusion (MPE) in nude mice. METHODS: Human lung carcinoma A549 cells were injected into the pleural cavity of nude mice to establish MPE model. The mice were randomly divided into model group and treatment group, and were orally administered with distilled water and TAE226 (20 mg/kg) in the same volume, respectively. The volume of pleural effusion and tumor weight of the two groups were observed. HE staining was used to reveal the histological changes and enzyme-linked immunosorbent assay (ELISA) was used to detect the IGF-1R protein expression. IGF-1R mRNA level in the tumor tissue was determined by RT-PCR. Microvessel density (MVD) and cell proliferation index (PI) were assessed by immunohistochemical analysis. The protein expression levels of IGF-1R, p-IGF-1R, PI3K and p-PI3K in the tumor tissue were determined by Western blotting. RESULTS: The volumes of pleural effusion were (241.4±89.7) µl and (121.7±78.8) µl in the model and treatment groups, respectively (P<0.05). The tumor weight of treatment group was (316.7±186.3) mg, significantly lower than that of the model group (671.4±281.4) mg (P<0.05). RT-PCR analysis showed that IGF-1R mRNA level was 0.914±0.029 in the treatment group, significantly lower than that of the model group (1.152±0.037, P<0.01). The ELISA data revealed that IGF-1R protein expression level of the model group was significantly higher than that of the treatment group [(41.0±4.7) µg/L vs. (24.0±3.1) µg/L, P<0.01]. Immunohistochemical analysis showed that there were significant differences between MVD and PI in the model and treatment groups [MVD, 34.75±3.49 vs. 22.25±3.63; PI, (75.25±7.15)% vs. (45.75±5.12)%; P<0.01 for both). Western blot data showed that IGF-1R and PI3K protein expression levels were not significantly different between the model and treatment groups (1.03±0.33 vs. 0.98±0.37 and 1.05±0.28 vs. 0.98±0.19), respectively (P>0.05), but p-IGF-1R and p-PI3K protein expression levels had significant differences between the two groups (1.08±0.10 vs. 0.51±0.08 and 1.12±0.09 vs. 0.86±0.09), respectively (P<0.01 for both). CONCLUSIONS: The IGF-1R inhibitor can effectively inhibit the formation of malignant pleural effusion. Its mechanism may be related to the suppression of tumor cell proliferation, invasion and angiogenesis through inhibition of PI3K signaling. TAE226 treatment may be a potential therapeutic regimen of treating malignant pleural effusion.

[The effect and injury to the airways of different sputum aspiration pressure in a rat model of mucus hypersecretion].

OBJECTIVE: To explore the optimal pressure of sputum aspiration to ensure the effectiveness and safety of clinical operation. METHODS: We established a rabbit model of airway mucus hypersecretion by aerosol acrolein inhalation, and the animals were divided into 4 groups randomly with different sputum aspiration pressure as follows: group A -75 mmHg (1 mmHg=0.133 kPa), group B -150 mmHg, group C -225 mmHg, group D -300 mmHg. Sputum aspiration efficiency and tracheal mucosal damage degree were evaluated by sputum volume, oxygen saturation changes, the pathological sections of tracheal mucosa and the expressions of IL-1ß and TNF-α in airway secretion. RESULTS: The sputum suction volume of group A, B, C, D were (2.72±0.24), (4.81±0.32), (5.03±0.37) and (6.29±0.51) ml, respectively, which was significantly higher in group D, but lower in group A, as compared to other groups (P<0.05). There were no significant differences between B and C groups. The maximal SpO2 decrease of C and D groups [(18.1±5.2)% and(32.4±8.4)%]were significantly higher than those in A and B groups [(4.4±1.7)% and (6.3±2.9)%], and group D was significantly more than group C, and the difference was statistically significant (P<0.05). There were no significant differences between A and B groups. HE staining of tracheal mucosa in C and D groups showed that the inflammatory cell infiltration and mucosal damage were more serious than A and B groups, but the airway mucosal damage of group A was the least. CONCLUSION: The pressure of -150 mmHg was more effective with high oxygen saturation and less airway injury, which may be suitable for clinical sputum aspiration.

Studies on different iron source absorption by in situ ligated intestinal loops of broilers.

The objective of this study was to investigate the iron source absorption in the small intestine of broiler. In situ ligated intestinal loops of 70 birds were poured into one of seven solutions, including inorganic iron (FeSO4, Fe2(SO4)3), organic Fe glycine chelate (Fe-Gly(II), Fe-Gly(III)), the mixtures (FeSO4 with glycine (Fe+Gly(II)), Fe2(SO4)3 with glycine (Fe+Gly(III)), and no Fe source (control). The total volume of 3-mL solution (containing 1 mg of elemental Fe) was injected into intestinal loops, and then 120-min incubation was performed. Compared with inorganic iron groups, in which higher FeSO4 absorption than Fe2(SO4)3 was observed, supplementation with organic Fe glycine chelate significantly increased the Fe concentration in the duodenum and jejunum (P < 0.05), however, decreased DMT1 and DcytB messenger RNA (mRNA) levels (P < 0.05). Organic Fe glycine chelate (Fe-Gly(II), Fe-Gly(III)) increased serum iron concentration (SI), compared with inorganic 3 valence iron groups (Fe2(SO4)3 and Fe+Gly(III)) (P < 0.05); moreover, lower TIBC value was observed for the chelate (P < 0.05); however, mixture of inorganic iron and glycine did not have a positive role at DMT1 and DcytB mRNA levels, SI and Fe concentrations in the small intestine. Those results indicated that the absorption of organic Fe glycine chelate was more effective than that of inorganic Fe, and the orders of iron absorption in the small intestine were: Fe-Gly(II), Fe-Gly(III) > FeSO4, Fe+Gly(II) > Fe2(SO4)3, Fe+Gly(III). Additionally, the simple mixture of inorganic iron and glycine could not increase Fe absorption, and the duodenum was the main site of Fe absorption in the intestines of broilers and the ileum absorbed iron rarely.

Laparoscopic intersphincteric resection for low rectal cancer: comparison of stapled and manual coloanal anastomosis.

AIM: The study aim was to analyse the safety and feasibility of laparoscopic intersphincteric resection with stapled coloanal anastomosis for low rectal cancer. METHOD: Between March 2009 and August 2010, 22 patients underwent laparoscopic intersphincteric resection with a stapled coloanal anastomosis without a diverting ileostomy. The results were compared retrospectively with hand-sewn coloanal anastomoses performed between January 2001 and May 2009, which included 55 open and 38 laparoscopic intersphincteric resections. The morbidity comparison only included data relevant to the anastomosis. Function was compared using the Saito function questionnaire and the Wexner score and only involved data relevant to the laparoscopy. RESULTS: The anastomotic complication rates were similar for fistula, bleeding and neorectal mucosal prolapse (P = 0.526, P = 0.653 and P = 0.411, respectively). Anastomotic leakage and stricture formation of the stapled coloanal anastomosis were significantly lower than those of the hand-sewn coloanal anastomosis (P = 0.037 and P = 0.028, respectively). There were no significant differences in the Saito function questionnaire and the Wexner score between the stapled and hand-sewn coloanal anastomotic groups (all P > 0.05). CONCLUSION: Laparoscopic intersphincteric resection with a stapled coloanal anastomosis is technically feasible and is less likely to result in anastomotic leakage and stricture formation than a hand-sewn anastomosis.

Spin-filtering, giant magnetoresistance, rectifying and negative differential resistance effects in planar four-coordinate Fe complex with graphene nanoribbon electrodes.

By using the nonequilibrium Green's function formalism combined with the density functional theory, we have investigated the spin-polarized transport properties of a planar four-coordinate Fe complex sandwiched between two zigzag-edge graphene nanoribbon (ZGNR) electrodes, where the ZGNRs are modulated by external magnetic field. The results show that the system can exhibit perfect dual spin-filtering and spin-rectifying effects at a wide bias range, giant magnetoresistance effect with large magnetoresistance ratio at small bias, and obvious negative differential resistance behavior. The mechanisms are proposed for these phenomena.

Relationship between medial plica and medial femoral condyle--a three-dimensional dynamic finite element model.

BACKGROUND: Many researches reported that the pathologic medial plica impinges on the facing medial femoral condyle during knee motion and leads to erosive changes of the articular cartilage. The purpose of this study was to construct a simplified three-dimensional dynamic finite element human knee model to evaluate the dynamics behaviour between different types of medial plicae with the facing medial femoral condyles during knee motion. METHODS: A three-dimensional dynamic finite element model composed of femur, tibia, covering cartilage and medial plica was developed. The kinematics of this simulation model was verified by previous findings during arthroscopic examination. The validated model was used to investigate and compare the magnitudes of the cyclic pressures acting on the cartilage of the medial femoral condyles by three different types of medial plicae with various Young's moduli. FINDINGS: All types of plicae remained in contact with the medial femoral condyles and shifted medially when the knees moved from extension to flexion. The contact pressures were positively correlated with the Young's moduli of the medial plicae. During the whole range of motion, the maximum contact pressures of all simulation scenarios occurred when the knees moved beyond 50° of flexion. When the Young's moduli of medial plicae were set greater than 60 MPa, all types of medial plicae would elicit contact pressures greater than 10 MPa on the medial femoral condyles. INTERPRETATION: The close relationship and possible high contact pressure between fibrotic medial plica and medial femoral condyle during knee motion might be a cause of cartilage damage on the medial femoral condyle and warrants further investigation.