Objective To prepare the recombinant Echinococcus granulosus Polo-like kinase 2 (rEgPLK2) protein and evaluate its immunoprotective efficacy against cystic echinococcosis, so as to provide insights into research and development of novel vaccines against echinococcosis. Methods The Polo-like kinase (PLK) protein sequences were retrieved from 12 species in the NCBI protein database, including E. granulosus and E. multilocularis. Multiple sequence alignment was performed using the Clustal Omega program, and structural visualization and homology analysis were conducted using the ESPript 3.2 program. The recombinant plasmid pET-30a-EgPLK2 was transformed into BL21(DE3) competent cells. Protein expression was induced with isopropyl-β-D-thiogalactoside (IPTG), and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed to characterize the expression and molecular weight of the rEgPLK2 protein. The purified rEgPLK2 protein was thoroughly emulsified with Freund’s complete adjuvant at a 1 : 1 volume ratio. Two New Zealand white rabbits were immunized with multipoint subcutaneous injection on the back at a dose of 300 μg per rabbit for primary immunization. For booster immunizations, the protein was emulsified with Freund’s incomplete adjuvant at a 1 : 1 volume ratio and administered on days 14, 28, and 42 after the primary immunization at a dose of 150 μg per rabbit. Serum was sampled from the rabbit ear vein on day 7 after the final immunization to yield anti-rEgPLK2 polyclonal antibodies. Antibody titer was determined by indirect enzyme-linked immunosorbent assay (ELISA), and antibody specificity was verified by Western blotting. The tissue localization of the EgPLK2 protein was detected in E. granulosus protoscoleces and adult worms using immunofluorescence assay (IFA). Eighteen 6- to 8-week-old female SPF-grade BALB/c mice were randomly divided into three groups, including the blank control group, rEgPLK2-ISA immunization group, and PBS-ISA adjuvant control group, of 6 mice each group. Mice in the rEgPLK2-ISA immunization group and PBSISA group received three primary immunizations via intramuscular injection, and animals in the rEgPLK2-ISA immunization group was inoculated with immunogens prepared by emulsifying rEgPLK2 protein with ISA 201 adjuvant at a 1 : 1 volume ratio (6 μg per mouse), while mice in the PBS-ISA adjuvant control group received an equal volume of PBS emulsified with ISA adjuvant at a 1 : 1 volume ratio. A fourth booster immunization was administered via intraperitoneal injection. Mice in the rEgPLK2-ISA immunization group received a booster immunization with 8 μg of rEgPLK2 protein per mouse, and animals in the PBS-ISA group received an equal volume of PBS, with immunizations given at 2-week intervals. Mice in the blank control group were given no treatment, and housed under standard conditions. Tail vein blood was collected from all mice 7 days after the final immunization, and levels of specific anti-rEgPLK2 IgG antibody and its subclasses (IgG1, IgG2a, IgG2b, IgG3) were measured by indirect ELISA. E. granulosus infection was modelled in mice through injection with 1 000 E. granulosus protoscoleces via intrahepatic portal vein in the rEgPLK2-ISA immunization group and PBS-ISA adjuvant control group 2 weeks after the last immunization. All mice were sacrificed and dissected. The number of cysts was counted in mouse livers, and the cyst reduction rate was calculated. Liver tissues were processed for paraffin sectioning and stained with hematoxylin and eosin (HE), and histopathological changes were examined under a light microscope. Results Sequence analysis revealed that EgPLK2 shared a high amino acid sequence homology with E. multilocularis PLK2 (EmPLK2) and contained the typical domains of the Polo-like kinase family, including the serine/threonine protein kinase catalytic domain (STKc) and Polo-box. The IPTG-induced rEgPLK2 protein was mainly expressed in the form of inclusion bodies, and the purified rEgPLK2 protein showed a relative molecular mass of approximately 70 kDa. The prepared rabbit anti-rEgPLK2 polyclonal antibody had a titer of 1 : 256 000, and Western blotting assay showed that this anti-body specifically recognized the rEgPLK2 protein with a relative molecular mass of approximately 70 kDa. Immunofluorescence assay showed that the EgPLK2 protein was localized in the excretory bladder and rostellum of E. granulosus protoscoleces, as well as the tegument, suckers, and inter-proglottid junctions of adult worms. Immunoprotective assay showed that the serum levels of specific anti-rEgPLK2 IgG, IgG1, IgG2a, and IgG2b antibodies were 2.92 ± 0.49, 0.33 ± 0.10, 0.31 (0.36), and 3.12 (1.73) in mice in the rEgPLK2-ISA immunization group, which were all significantly higher than those in the PBS-ISA adjuvant control group (0.14 ± 0.04, 0.07 ± 0.01, 0.12 ± 0.04, and 0.11 ± 0.04, respectively) (t = 19.28 and 8.46, Z = 3.75 and 4.15; all P values < 0.001); however, there was no significant difference in the serum anti-IgG3 antibody level between the rEgPLK2-ISA immunization group and the PBS-ISA adjuvant control group [0.07 (0.01) vs. 0.073 (0.07); Z = 0.69, P > 0.05)]. In the mouse model of E. granulosus infections, the area of hepatic lesions was reduced and the inflammatory infiltration was alleviated in the rEgPLK2-ISA immunization group than in the PBS-ISA adjuvant control group, and the number of hepatic cysts was higher in the PBS-ISA adjuvant control group than in the rEgPLK2-ISA immunization group [8.00 (2.00) vs. 1.00 (0.75); Z = −2.93, P < 0.01], with a cyst reduction rate of 80.40%. Indirect ELISA assay measured higher serum levels of specific anti-rEgPLK2 IgG (3.28 ± 0.48 vs. 0.11 ± 0.04; t = 15.86, P < 0.01), IgG1 (0.29 ± 0.02 vs. 0.09 ± 0.01; t = 15.67, P < 0.01), IgG2a [3.71 (1.09) vs. 0.08 (0.03); Z = 2.88, P < 0.01], and IgG2b antibodies [3.34 (1.01) vs. 0.08 (0.03); Z = 2.88, P < 0.01] in the rEgPLK2-ISA immunization group than in the PBS-ISA adjuvant control group, and there was no significant difference in the serum level of the specific anti-rEgPLK2 IgG3 antibody between the rEgPLK2-ISA immunization group and the PBS-ISA adjuvant control group (0.07 ± 0.01 vs. 0.07 ± 0.01; t = 1.29, P > 0.05). Conclusions The prokaryotic expression system has been successfully constructed for the EgPLK2 gene and the anti-rEgPLK2 polyclonal antibody has been obtained. The rEgPLK2 protein exhibits a high immunogenicity, and is effective to protect against E. granulosus infection, and inhibits cyst development, which is a promising candidate vaccine target against cystic echinococcosis.

Inflammatory bowel disease (IBD) is an idiopathic intestinal inflammatory condition with chronic and relapsing manifestations and is characterized by a disturbance in the interplay between the intestinal microbiota, the gut, and the brain. The microbiota-gut-brain axis involves interactions among the nervous system, the neuroendocrine system, the gut microbiota, and the host immune system. Increasing published data indicate that psychological stress exacerbates the severity of IBD due to its negative effects on the microbiota-gut-brain axis, including alterations in the stress response of the hypothalamic-pituitary-adrenal (HPA) axis, the balance between the sympathetic nervous system and vagus nerves, the homeostasis of the intestinal flora and metabolites, and normal intestinal immunity and permeability. Although the current evidence is insufficient, psychotropic agents, psychotherapies, and interventions targeting the microbiota-gut-brain axis show the potential to improve symptoms and quality of life in IBD patients. Therefore, further studies that translate recent findings into therapeutic approaches that improve both physical and psychological well-being are needed.
Humans ; Inflammatory Bowel Diseases/metabolism* ; Stress, Psychological/microbiology* ; Gastrointestinal Microbiome/physiology* ; Brain/metabolism* ; Hypothalamo-Hypophyseal System ; Pituitary-Adrenal System ; Animals

Objective The study aims to investigate the immunological functions of the nucleocapsid (N) protein of the novel coronavirus Omicron (BA.1, BA.2) and evaluate the differences among different N proteins of mutant strains in immunogenicity. Methods By aligning sequences, the mutation sites of the Omicron (BA.1, BA.2) N protein relative to prototype strain of the novel coronavirus (Wuhan-Hu-1) were determined. The pET-28a-N-Wuhan-Hu-1 plasmid was used as template to construct pET-28a-BA.1/BA.2-N through single point mutation or homologous recombination. The three kinds of N protein were expressed in prokaryotic system, purified through Ni-NTA affinity chromatography, and then immunized into mice. The titer and reactivity of the polyclonal antibody, as well as the expression level of IL-1β and IFN-γ in mouse spleen cells, were detected using indirect ELISA and Western blot assay. Results The constructed prokaryotic expression plasmids were successfully used to express the Wuhan-Hu-1 N, BA.1 N, and BA.2 N proteins in E.coli BL21(DE3) at 37 DegreesCelsius for 4 hours. The indirect ELISA test showed that the titers of polyclonal antibody prepared by three N proteins were all 1:51 200. All three N proteins can increase the expression of IFN-γ and IL-1β cytokines, but the effect of Omicron N protein in activing two cytokines was more obvious than that of Wuhan-Hu-1 N protein. Conclusion The study obtained three new coronavirus N proteins and polyclonal antibodies, and confirmed that mutations in the amino acid sites of the N protein can affect its immunogenicity. This provides a basis for developing rapid diagnostic methods targeting N protein of different novel coronavirus variants.
Animals ; Mice ; SARS-CoV-2/genetics* ; Coronavirus Nucleocapsid Proteins/immunology* ; Nucleocapsid Proteins/isolation & purification* ; COVID-19/immunology* ; Antibodies, Viral/immunology* ; Mice, Inbred BALB C ; Interferon-gamma/metabolism* ; Interleukin-1beta/metabolism* ; Female ; Escherichia coli/metabolism* ; Mutation ; Humans

BACKGROUND: Lung cancer is one of the most common malignant tumors worldwide and a major cause of cancer-related deaths. Early-stage lung cancer is often manifested as pulmonary nodules, and accurate assessment of the malignancy risk is crucial for prolonging survival and avoiding overtreatment. This study aims to construct a model based on image feature parameters automatically extracted by artificial intelligence (AI) to evaluate its effectiveness in predicting the malignancy of part-solid nodule (PSN). METHODS: This retrospective study analyzed 229 PSN from 222 patients who underwent pulmonary nodule resection at Lanzhou University Second Hospital between October 2020 and February 2025. According to pathological results, 45 cases of benign lesions and precursor glandular lesion were categorized into the non-malignant group, and 184 cases of pulmonary malignancies were categorized into the malignant group. All patients underwent preoperative chest computed tomography (CT), and AI software was used to extract imaging feature parameters. Univariate analysis was used to screen significant variables; variance inflation factor (VIF) was calculated to exclude highly collinear variables, and LASSO regression was further applied to identify key features. Multivariate Logistic regression was used to determine independent risk factors. Based on the selected variables, five models were constructed: Logistic regression, random forest, XGBoost, LightGBM, and support vector machine (SVM). Receiver operating characteristic (ROC) curves were used to assess the performance of the models. RESULTS: The independent risk factors for the malignancy of PSN include roughness (ngtdm), dependence variance (gldm), and short run low gray-level emphasis (glrlm). Logistic regression achieved area under the curves ( AUCs) of 0.86 and 0.89 in the training and testing sets, respectively, showing good performance. XGBoost had AUCs of 0.78 and 0.77, respectively, demonstrating relatively balanced performance, but with lower accuracy. SVM showed an AUC of 0.93 in the training set, which decreased to 0.80 in the testing set, indicating overfitting. LightGBM performed excellently in the training set with an AUC of 0.94, but its performance declined in the testing set, with an AUC of 0.88. In contrast, random forest demonstrated stable performance in both the training and testing sets, with AUCs of 0.89 and 0.91, respectively, exhibiting high stability and excellent generalizability. CONCLUSIONS The random forest model constructed based on independent risk factors demonstrated the best performance in predicting the malignancy of PSN and could provide effective auxiliary predictions for clinicians, supporting individualized treatment decisions.
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Humans ; Male ; Female ; Lung Neoplasms/pathology* ; Middle Aged ; Retrospective Studies ; Artificial Intelligence ; Aged ; Tomography, X-Ray Computed ; Adult ; Solitary Pulmonary Nodule/diagnostic imaging* ; ROC Curve

Objective:This study utilizes data from the 2021 Chinese Longitudinal Healthy Longevity and Happy Family Survey(CLHLS-HF)to examine the current status of Long-Term Care Insurance(LTCI)implementation and to identify the factors influencing whether disabled elderly individuals receive formal care services.The study aims to provide policy recommendations to enhance the effectiveness and equity of the system.Methods:In this cross-sectional study, a sample of 1 447 older participants with dependency, residing in LTCI pilot areas and meeting the inclusion criteria from the 2021 CLHLS-HF, was selected.Chi-square tests and binary logistic regression analyses were employed to explore the factors influencing the receipt of formal care by dependent older individuals.Results:Among the 1 447 participants, there were 496 males with an average age of 92 years(SD 9)and 951 females with an average age of 95 years(SD 9). Of these, 701 received formal care.The logistic regression analysis revealed that factors influencing the receipt of formal care included urban residence( OR=2.237, 95% CI: 1.675-2.987, P<0.001), residing in the eastern region( OR=2.907, 95% CI: 1.747-4.837, P<0.001), living in the western region( OR=3.132, 95% CI: 1.816-5.501, P<0.001), having no children( OR=2.478, 95% CI: 1.108-5.540, P=0.027), and the degree of disability, with severe disability being more likely to receive care compared to mild( OR=0.497, 95% CI: 0.388-0.637, P<0.001)and moderate disabilities( OR=0.589, 95% CI: 0.433-0.801, P=0.001). Conclusions:Dependent older individuals in the eastern and western regions, particularly those without children or with severe disabilities, are more likely to receive formal care through the LTCI system.However, there are substantial inequities in LTCI coverage among individuals with varying degrees of disability.To enhance the effectiveness of the LTCI system, greater efforts should be directed towards economically disadvantaged regions and older individuals with mild to moderate disabilities, thereby ensuring better protection for the disabled population.

Objective To evaluate the predictive ability and clinical application value of artificial intelligence (AI) systems in the benign and malignant differentiation and pathological type of pulmonary nodules, and to summarize clinical application experience. Methods A retrospective analysis was conducted on the clinical data of patients with pulmonary nodules admitted to the Department of Thoracic Surgery, Second Hospital of Lanzhou University, from February 2016 to February 2025. Firstly, pulmonary nodules were divided into benign and non-benign groups, and the discriminative abilities of AI systems and clinicians were compared. Subsequently, lung nodules reported as precursor glandular lesions (PGL), microinvasive adenocarcinoma (MIA), and invasive adenocarcinoma (IAC) in postoperative pathological results were analyzed, comparing the efficacy of AI systems and clinicians in predicting the pathological type of pulmonary nodules. Results In the analysis of benign/non-benign pulmonary nodules, clinical data from a total of 638 patients with pulmonary nodules were included, of which there were 257 males (10 patients and 1 patient of double and triple primary lesions, respectively) and 381 females (18 patients and 1 patient of double and triple primary lesions, respectively), with a median age of 55.0 (47.0, 61.0) years. Different lesions in the same patient were analyzed as independent samples. Univariate analysis of the two groups of variables showed that, except for nodule location, the differences in the remaining variables were statistically significant (P<0.05). Multivariate logistic regression analysis showed that age, nodule type (subsolid pulmonary nodule), average density, spicule sign, and vascular convergence sign were independent influencing factors for non-benign pulmonary nodules, among which age, nodule type (subsolid pulmonary nodule), spicule sign, and vascular convergence sign were positively correlated with non-benign pulmonary nodules, while average density was negatively correlated with the occurrence of non-benign pulmonary nodules. The area under the receiver operating characteristic curve (AUC) of the malignancy risk value given by the AI system in predicting non-benign pulmonary nodules was 0.811, slightly lower than the 0.898 predicted by clinicians. In the PGL/MIA/IAC analysis, clinical data from a total of 411 patients with pulmonary nodules were included, of which there were 149 males (8 patients of double primary lesions) and 262 females (17 patients of double primary lesions), with a median age of 56.0 (50.0, 61.0) years. Different lesions in the same patient were analyzed as independent samples. Univariate analysis results showed that, except for gender, nodule location, and vascular convergence sign, the differences in the remaining variables among the three groups of PGL, MIA, and IAC patients were statistically significant (P<0.05). Multinomial multivariate logistic regression analysis showed that the differences between the parameters in the PGL group and the MIA group were not statistically significant (P>0.05), and the maximum diameter and average density of the nodules were statistically different between the PGL and IAC groups (P<0.05), and were positively correlated with the occurrence of IAC as independent risk factors. The average AUC value, accuracy, recall rate, and F1 score of the AI system in predicting lung nodule pathological type were 0.807, 74.3%, 73.2%, and 68.5%, respectively, all better than the clinical physicians’ prediction of lung nodule pathological type indicators (0.782, 70.9%, 66.2%, and 63.7% respectively). The AUC value of the AI system in predicting IAC was 0.853, and the sensitivity, specificity, and optimal cutoff value were 0.643, 0.943, and 50.0%, respectively. Conclusion This AI system has demonstrated high clinical value in predicting the benign and malignant nature and pathological type of lung nodules, especially in predicting lung nodule pathological type, its ability has surpassed that of clinical physicians. With the optimization of algorithms and the adequate integration of multimodal data, it can better assist clinical physicians in formulating individualized diagnostic and treatment plans for patients with lung nodules.

Objective To assess the evolving disease burden of esophageal and gastric cancers in China from 1990 to 2021, with a focus on gender disparities, and construct a predictive model to forecast disease trends from 2022 to 2031, aiming to optimize targeted prevention strategies. Methods Epidemiological data for esophageal and gastric cancers in China (1990-2021) were extracted from the Global Burden of Disease (GBD) 2021 database. Temporal trends were analyzed using Joinpoint regression (version 4.9.1.0), and future trends were predicted via the GM (1, 1) model under grey system theory. Results From 1990 to 2021, tobacco- and alcohol-attributable burdens of esophageal cancer increased, while tobacco- and diet-related burdens of gastric cancer showed no significant change. Deaths and disability-adjusted life years (DALY) for esophageal cancer rose by 40.61% and 17.89%, respectively; gastric cancer deaths increased by 18.95%, though DALY decreased by 1.22%. Both cancers exhibited significant declines in age-standardized mortality rates (−45.78% for esophageal cancer, −53.29% for gastric cancer) and age-standardized DALY rates (−51.45% for esophageal cancer, −57.58% for gastric cancer). China’s age-standardized mortality and DALY rates for both cancers remained consistently higher than global averages. Males exhibited disproportionately higher burdens than females. Predictive modeling projected continued but decelerating declines in disease burdens for both cancers by 2031. Conclusion Over three decades, China achieves measurable reductions in esophageal and gastric cancer burdens, though gastric cancer burdens remain higher than esophageal cancer. Persistent disparities relative to global levels, elevated male burdens, and aging demographics highlight the urgency for prioritized interventions targeting high-risk populations.

Objective:To observe the clinical efficacy and safety of Jianpi Bushen Jiedu Prescription combined with 5-fluorouracil (5-FU)-based chemotherapy and targeted therapy for the treatment of advanced colorectal cancer patients with liver and kidney yin deficiency combined with spleen deficiency pattern.Methods:A randomized controlled trial was conducted. A total of 72 hospitalized patients with advanced colorectal cancer treated at the Department of Oncology, Nanjing Hospital of Traditional Chinese Medicine Affiliated to Nanjing University of Chinese Medicine from October 2022 to January 2024 were enrolled as study subjects. Using a random number table method, they were allocated into two groups, with 36 patients in each group. The control group received the mFOLFOX6/FOLFIRI combined with bevacizumab regimen, while the treatment group was administered additional oral Jianpi Bushen Jiedu Prescription on the basis of the control group. Two weeks was a cycle in both groups, with a total of 6 cycles of treatment. Serum levels of carcinoembryonic antigen (CEA), carbohydrate antigen 199 (CA199), and carbohydrate antigen 724 (CA724) were detected using electrochemiluminescence; the Karnofsky Performance Status (KPS) scale was utilized to evaluate patients' functional status; vital signs were continuously monitored, and adverse reactions were recorded. The short-term efficacy and TCM syndrome efficacy of patients were evaluated.Results:The treatment group demonstrated higher objective response rate (ORR) [31.25% (10/32) vs. 21.88% (7/32), χ2=0.72] and disease control rate (DCR) [84.38% (27/32) vs. 71.88% (23/32), χ2=1.46] compared to the control group, without statistical significance ( P>0.05). Post-treatment levels of CEA [4.09 (3.31,8.57) μg/L vs. 10.07 (4.55,22.35) μg/L, Z=-2.10] and CA72-4 [4.54 (2.04,10.99) mU/L vs. 9.48 (4.34,18.95) mU/L, Z=-2.52] in the treatment group were significantly lower than those in the control group ( P<0.05). The total effective rate of TCM syndrome was significantly higher in the treatment group [78.13% (25/32)] compared with the control group [50.00% (16/32)], with statistical significance ( χ2=5.50, P=0.019). Post-treatment KPS scores in the treatment group [80.0 (80.0, 80.0) vs. 70.0 (62.5, 80.0), Z=-2.76] were significantly higher compared with the control group ( P<0.01). During the treatment period, the treatment group showed statistical significance compared with the control group in the incidence of hemoglobin decrease ( χ2=4.66), leukopenia decrease ( χ2=4.27), and peripheral neuropathy ( χ2=3.93), with statistical significance ( P<0.05). Conclusion:The addition of Jianpi Bushen Jiedu Prescription to 5-FU-based chemotherapy combined with targeted therapy demonstrates significant clinical benefits in advanced colorectal cancer patients, including reducing tumor marker levels, alleviating clinical symptoms, improving quality of life, and mitigating treatment-related toxicities, with a good safety.

Objective To explore the value of artificial intelligence-assisted compressed sensing(ACS)-MR cine imaging(Cine)for assessing biventricular function and left ventricular myocardial strain compared with conventional cardiac Cine and united compressed sensing(uCS)-Cine.Methods A total of 30 subjects who underwent conventional Cine,uCS-Cine and ACS-Cine were prospectively enrolled.Based on a 5-point scale,subjective scoring of image quality was performed and compared among 3 sequences.Biventricular function parameters and myocardial strain parameters of the left ventricle,including left ventricular end-diastolic volume(LVEDV),left ventricular end-systolic volume(LVESV),left ventricular ejection fraction(LVEF),left ventricular end-diastolic mass(LVEDM),right ventricular end-diastolic volume(RVEDV),right ventricular end-systolic volume(RVESV),right ventricular ejection fraction(RVEF),left ventricular global radial strain(LVGRS),left ventricular global circumferential strain(LVGCS)and left ventricular global longitudinal strain(LVGLS)were measured and compared among sequences.Results The subjective image quality scores of all 3 sequences were≥3,of ACS-Cine and conventional Cine were not significantly different(adjusted P=0.306)but both slightly higher than that of uCS-Cine(both adjusted P＜0.05).LVEDV,LVEF and LVEDM based on ACS-Cine and uCS-Cine were not significantly different(all adjusted P＞0.05),but all lower than those of conventional Cine(all adjusted P＜0.05).No significant difference of LVESV was found between each two sequences(all adjusted P＞0.05).RVEDV based on ACS-Cine was lower than that based on conventional Cine,RVESV based on ACS-Cine was higher than that based on uCS-Cine,and RVEF based on ACS-Cine was lower than that based on uCS-Cine and conventional Cine(all adjusted P＜0.05),while no significant difference of right ventricular functional parameters was observed between uCS-Cine and conventional Cine(all adjusted P＞0.05).Both ACS-Cine and uCS-Cine had lower LVGRS and LVGCS than conventional Cine(all adjusted P＜0.05),with no significant difference was found between uCS-Cine and ACS-Cine(both adjusted P＞0.05).No significant difference of LVGLS was observed among 3 sequences(P＞0.05).Conclusion ACS-Cine could be used as appropriate supplement to conventional Cine for clinical assessment of biventricular function and left ventricular myocardial strain.

Objective To analyze the correlation between the Patellotrochlear index at different knee flexion angles and recurrent patellar dislocation,and to find the optimal knee flexion angle and the best diagnostic cut-off value for predicting recurrent patellar dislocation.Methods A total of 35 patients clinically diagnosed with recurrent patellar dislocation(study group)were selected.The lengths of the central sagittal plane of the patellar cartilage and the corresponding femoral trochlear cartilage were measured at knee flexion angles ranging from 0° to 70°,in 10° increments.The Patellotrochlear index was calculated and compared with the MRI data from 55 healthy volunteers(control group).Results The Patellotrochlear index in the study group and the control group showed a positive correlation with the knee flexion angle(r=0.935 and 0.909,P＜0.001).Statistically significant differences were found between the two groups at knee flexion angles of 0°,10°,20°,30°,and 40°(t=7.480,5.742,5.200,3.558,4.271,P＜0.05).The predictive efficacy of the Patellotrochlear index for recurrent patellar dislocation varied at different knee flexion angles,with the area under the curve(AUC)and the best diagnostic cut-off values of 0.891,0.834,0.778,0.710,0.741 and 0.195,0.323,0.486,0.606,0.712,respectively.Conclusion There are significant differences in the Patellotrochlear index at different knee flexion angles.A knee flexion angle of 0° is the optimal knee flexion angle for the Patellotrochlear index to predict recurrent patellar dislocation,with a recommended best diagnostic cut-off value of 0.195.