OBJECTIVE: To explore the differences in the implantation safety and stability of a S ₁ alar-iliac screw (S1AIS) or S2AIS for sacroiliac joint fixation, providing reference for selecting appropriate internal fixation in clinical practice. METHODS: Patients who underwent pelvic CT examination between January 2024 and December 2024 were selected. CT data from 80 patients with normal pelvic structure who met the selection criteria were included in a 1∶1 male to female ratio. CT digital reconstruction technology was used to measure the transverse and longitudinal diameters of the S1AIS and S2AIS insertable ranges, as well as the length, width, and sacral side length of the screw trajectory. The pelvic CT data from 30 patients were randomly selected based on a 1∶1 male to female ratio for three-dimensional (3D) printing of pelvic samples. The S1AIS/S2AIS with a diameter of 6.5 mm and 8.0 mm were implanted at the optimal entry/exit points on the left and right sides, respectively, to observe the perforation of the screw trajectory. The pelvic CT data from 1 patient was randomly selected for 3D printing of 10 pelvic samples to simulate Tile C2 fracture. They were divided into S1AIS group ( n=5) and S2AIS group ( n=5), with one S1AIS and one S2AIS fixation used for posterior sacroiliac joint separation, and the specimen stiffness and maximum load were measured by using an electric tension torsion dual axis universal mechanical tester. RESULTS: The anatomical parameter measurement showed that there was no significant difference in the length and width of the screw trajectory between S1AIS and S2AIS ( P>0.05), but the transverse and longitudinal diameters of the insertable ranges, as well as the sacral side length of the screw trajectory, were all greater than those of S2AIS, with significant differences ( P<0.05). After simulating the implantation of S1AIS and S2AIS with a diameter of 6.5 mm in pelvic specimens, no screw penetration was observed. Both S1AIS and S2AIS with a diameter of 8.0 mm showed screw penetration, with S2AIS having a higher incidence of posterior lateral sacral cortical penetration (46.7%) than S1AIS (3.3%) ( P<0.05). The biomechanical test showed that the stiffness and maximum load of S2AIS were significantly lower than those of S1AIS ( P<0.05). CONCLUSION As a method to fix the sacroiliac joint, the S1AIS has a larger insertable range, a longer sacral side length of the screw trajectory, a lower incidence of posterior lateral cortical rupture of the sacrum, and a greater fixation strength than S2AIS. Therefore, the implantation safety and fixation stability of the S1AIS are superior to S2AIS, and a diameter less than 8.0 mm screws should be selected as S2AIS for Chinese people.
Humans ; Bone Screws ; Sacroiliac Joint/diagnostic imaging* ; Male ; Female ; Sacrum/diagnostic imaging* ; Fracture Fixation, Internal/instrumentation* ; Ilium/diagnostic imaging* ; Tomography, X-Ray Computed ; Middle Aged ; Adult ; Printing, Three-Dimensional ; Aged

Objective:To establish a predictive model for the risk of cognitive impairment in patients with hypertension.Methods:Data were obtained from the China Health and Retirement Longitudinal Study(CHARLS),and 17 indicators were analyzed,including demographic features,behavioral factors,and health status.The study cohort was randomly divided into a training set(n=2 918)and an internal validation set(n=1 249)at a ratio of 7∶3,and 1 457 patients with hypertension who were treated in Chongqing Traditional Chinese Medicine Hospital from January to December 2024 were included as an external validation set.The least absolute shrinkage and selection operator regression analysis was used to identify predictive variables,and 10-fold cross-validation was used to determine the optimal model.A logistic regression model was used to investigate the risk factors for cognitive impairment in patients with hypertension,and then a nomogram prediction model was established.The calibration curve was used to assess the accuracy of the model,and the area under the ROC curve(AUC)and the decision curve analysis were used to assess the predictive performance of the model.Results:A total of 4167 hypertensive patients aged≥45 years were included from the CHARLS database,among whom 668 had cognitive impairment.The multivariate logistic regression analysis showed that age(odds ratio[OR]=1.408,95%CI=1.040-1.056),sex(OR=0.570,95%CI=0.492-0.660),body mass index(OR=0.931,95%CI=0.914-0.948),educational level(OR=0.235,95%CI=0.200-0.277),place of residence(OR=1.674,95%CI=1.447-1.936),physi-cal activity(OR=0.459,95%CI=0.373-0.562),depression(OR=1.386,95%CI=1.198-1.604),and total cholesterol level(OR=0.997,95%CI=0.995-0.999)were predictive variables.The ROC curve analysis showed that the nomogram model had good performance,with an AUC of 0.814(95%CI=0.802-0.826)in the training set,0.817(95%CI=0.788-0.846)in the internal validation set,and 0.725(95%CI=0.699-0.752)in the external validation set.Conclusion:The nomogram model developed in this study can effectively predict the risk of cognitive impairment in Chinese patients with hyperten-sion and has a good application value.

Objective To establish an ultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry(UPLC-QTOF-MS)method for identifying the active ingredients of Zhizi Houpu decoction,and to predict its material basis and mechanism of anti-insomnia effects using network pharmacology.Methods The chemical components of Zhizi Houpu decoction were identified according to UHPLC-QTOF-MS ion fragmentation rule combined with compound library and literature review.Components with oral bioavailability(OB)≥30％and drug-like properties(DL)≥0.18 were selected to construct the Zhizi Houpu decoction-active ingredients-target network.The STRING database and the Database for Annotation,Visualization,and Integrated Discovery(DAVID)were used to screen key target proteins.Subsequently,enrichment analysis was performed for biological processes,molecular functions,cellular components,and signaling pathways.Results A total of 107 chemical components were identified,including 35 compounds related to insomnia and 11 anti-insomnia targets such as AKT serine/threonine kinase 1,tumor protein 53,and prostaglandin-endoperoxide synthase 2.Gene Ontology functional enrichment analysis indicated that Zhizi Houpo decoction may exert its effects through cellular components such as the presynaptic membrane,dendrite,and plasma membrane,by participating in biological processes like chemical synaptic transmission,G protein signaling pathway,and neuron apoptosis,and by regulating molecular functions such as G protein-coupled serotonin receptor activity.Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed that its anti-insomnia effects were mainly concentrated in pathways such as neuroactive ligand-receptor interaction,calcium signaling pathway,serotonergic synapse,and cyclic adenosine monophosphate signaling pathway.Conclusion The anti-insomnia effect of Zhizi Houpo decoction is the result of a synergistic action involving multiple components,multiple targets,and multiple pathways.Its material basis and mechanism of action are primarily related to regulating biological processes such as neurotransmitter metabolism,synaptic function,neuronal apoptosis,and inflammatory response.

Objective To investigate the role of lupeol in mitigating chondrocyte senescence in osteoarthritis(OA)by regulating autophagy through the sirtuin 3(SIRT3)/mechanistic target of rapamycin kinase(mTOR)pathway.Methods Knee articular chondrocytes from primary-generation mice were isolated and divided into different groups,including a control group,a lupeol group(given 2.5,5,10,20,and 40 μmol/L lupeol),a tert-butyl hydrogen peroxide(TBHP)group(receiving 50 μmol/L TBHP),TBHP+lupeol group,TBHP+lupeol+chloroquine(CQ)group(receiving 20 μmol/L CQ,an autophagy inhibitor),TBHP+lupeol+si-NC group,and TBHP+lupeol+si-SIRT3 group.Cell proliferation,reactive oxygen species(ROS)levels,and apoptosis were determined by CCK-8,DCFH-DA probe,and flow cytometry.Cell senescence was evaluated by β-gal staining.Western blot was used to determine the expressions of SIRT3,mTOR,senescence marker proteins(p21 and p16),extracellular matrix(ECM)degradation-related proteins(aggrecan,collagen Ⅱ,ADAMTS5,and MMP13),and autophagy-related proteins(LC3B Ⅰ,LC3BⅡ,and P62).RT-qPCR was used to determine the mRNA levels of senescence-associated secretory phenotypes(SASP),including IL-6,Cxcl10,MCP1,and MMP3.The expression of LC3 was detected by immunofluorescence.Autophagosomes were observed by transmission electron microscopy.A total of 30 male wild-type C57BL/6 mice were divided into different groups(n=10),including a Sham group,an OA group,and an OA+lupeol group receiving 50 mg/(kg·d)lupeol via gastric gavage.Cartilage damage was evaluated by safranin O-fast green staining.Results Based on the results of cell viability assay,20 μmol/L lupeol treatment for 24 h was identified as the optimal intervention concentration and duration.Compared with that in the TBHP group,cell viability was elevated in the TBHP+lupeol group(P＜0.05);ROS production,the proportion of β-gal-positive cells,the protein expression levels of p21 and p16,and the mRNA levels of SASP were decreased(P＜0.05);the protein levels of aggrecan and collagen Ⅱ were elevated and the protein levels of ADAMTS5 and MMP13 were decreased(P＜0.05);apoptosis was reduced(P＜0.05);P62 protein levels were reduced and the LC3B Ⅱ/LC3B Ⅰ ratio,the intensity of LC3B fluorescence spots,and the number of autophagosomes were increased(P＜0.05);the expression level of SIRT3 was elevated and the level of mTOR phosphorylation was reduced(P＜0.05)in the TBHP+Lupeol group.CQ treatment effectively abolished the promotion effects of lupeol on cell viability and autophagy,and the inhibitory effects of lupeol on ROS level,cell senescence,ECM degradation,and apoptosis(P＜0.05).Silencing of SIRT3 reversed the inhibitory effect of lupeol on mTOR phosphorylation level and the promotion effect of lupeol on autophagy(P＜0.05).In the in vivo experiment,compared with the OA group,the OA+lupeol group showed reduced cartilage degeneration and lower scores for the Osteoarthritis Research Society International grading system(P＜0.05).The OA+lupeol group also showed up-regulated SIRT3 expression,reduced mTOR phosphorylation level,increased LC3B Ⅱ/LC3B Ⅰ ratio,reduced MMP13 protein level,and reduced mRNA level of SASP(P＜0.05).Conclusion Lupeol alleviates chondrocyte senescence in osteoarthritis by regulating autophagy through the SIRT3/mTOR pathway.

ObjectiveTo evaluate the clinical efficacy and safety of Tongluo Mingmu capsules in the treatment of diabetic retinopathy with blood stasis， collateral obstruction， and Qi and Yin deficiency syndrome. MethodA randomized， double-blind， positive-control， and multi-center clinical trial design method was used. 416 patients with diabetic retinopathy with blood stasis， collateral obstruction， and Qi and Yin deficiency syndrome in four test centers were included （the ratio of the treatment group to the control group was 3∶1）. On the basis of standardized hypoglycemic treatment， the treatment group was given both four Tongluo Mingmu capsules and two Calcium Dobesilate capsule agents three times a day， while the control group were given both two Calcium Dobesilate capsules and four Tongluo Mingmu capsule agents three times a day. The course of treatment was 12 weeks. The curative effect of Tongluo Mingmu capsules was evaluated by comparing the comprehensive curative effect of diabetic retinopathy， traditional Chinese medicine（TCM） syndrome score， corrected visual acuity， fundus changes， fundus fluorescence angiography， and other curative effect indexes before and after treatment in the two groups. At the same time， general examination， laboratory examination， and adverse events were performed to evaluate the safety of the drug. ResultThe baseline demographic data and disease characteristics of the treatment group and the control group were balanced and comparable， with the difference not statistically significant. After 12 weeks of treatment， the total effective rate of the comprehensive curative effect of diabetic retinopathy in the treatment group （61.0%， 189/310） was better than that in the control group （44.1%， 45/102）， and the difference was statistically significant （χ²=8.880， P<0.01）. The total effective rate of TCM syndromes in the treatment group （88.4%， 259/293） was better than that in the control group （69.9%， 65/93）， and the difference was statistically significant （χ²=17.927， P<0.01）. The disappearance rate of dry eyes （χ²=8.305）， dull complexion （χ²=4.053）， lassitude （χ²=10.267）， shortness of breath （χ²=8.494）， and dry stool （χ²=8.657） in the treatment group was higher than that in the control group， and the difference between the groups was statistically significant （P<0.05， P<0.01）. In terms of improving corrected visual acuity （χ²=8.382）， fundus changes （χ²=6.026） ， the treatment group was significantly better than the control group （P<0.05）. During the trial， the incidence of adverse events in the treatment group and the control group was 1.3% and 2.9%， respectively. There was no significant difference between the two groups. In addition， there were no serious adverse events and adverse events leading to withdrawal in both groups. ConclusionTongluo Mingmu capsules can improve the comprehensive curative effect of diabetic retinopathy and enhance the efficacy of TCM syndromes， visual acuity， fundus changes， and fundus fluorescein angiography， with great safety. Therefore， it can provide a new alternative therapeutic drug for patients with diabetic retinopathy.

BACKGROUND:Glucocorticoid-induced osteoporosis is a common complication of systemic glucocorticoid therapy,which is mainly characterized by its inhibitory effect on osteoblasts.Eriodictyol inhibits osteoclast differentiation and osteoporosis-induced by ovariectomy.However,it is unclear whether eriodictyol regulates glucocorticoid-induced osteoblasts. OBJECTIVE:To explore whether eriodictyol plays a role in glucocorticoid-induced osteoblast apoptosis and its potential regulatory mechanisms. METHODS:Dexamethasone-pretreated osteoblasts MC3T3-E1 were treated with the different concentrations(0,0.5,1,2.5,5,10 μmol/L)of eriodictyol or 5 μmol/L 3-methyladenine,an autophagy inhibitor,and then transfected with heme oxygenase 1 overexpression vector(pcDNA-HMOX1)and empty vector(pcDNA vector).Cell proliferation and apoptosis were assessed by using cell counting kit-8 assay and flow cytometry,respectively.The activity of caspase-3 was detected with ELISA.Western blot assay was used to detect the protein expression of autophagy-related proteins LC3-Ⅱ/LC3-Ⅰ,p62,Atg5 and Atg12,the expression of apoptotic related proteins Bax and Bcl-2,as well as the protein expression of AMPK and p-AMPK. RESULTS AND CONCLUSION:Low concentrations of eriodictyol were non-toxic to MC3T3-E1 cells and promoted cell proliferation,as well as increased the expression of autophagy related proteins LC3-Ⅱ/LC3-Ⅰ,p62,Atg5 and Atg12,decreased caspase-3 enzyme activity,inhibited Bax protein expression,promoted Bcl-2 protein expression and reduced dexamethasone-induced apoptosis in MC3T3-E1 cells in a dose-dependent manner.Moreover,eriodictyol significantly promoted heme oxygenase 1 expression in osteoblasts,whereas overexpression of heme oxygenase 1 promoted AMPK phosphorylation,activated autophagy,and inhibited dexamethasone-induced osteoblast apoptosis.While 3-methyladenine treatment counteracted the effects of heme oxygenase 1 overexpression on MC3T3-E1 cells.To conclude,low concentration of Eriodictyol is non-toxic to osteoblasts and activates AMPK signaling pathway by upregulating the expression of heme oxygenase 1,thereby promoting autophagy and inhibiting dexamethasone-induced osteoblast apoptosis.Eriodictyol has great potential for the treatment of glucocorticoid-induced osteoporosis.

Objective To investigate the effect of radiation on cardiomyocyte apoptosis and its related mechanism.Methods Rat H9C2 cardiomyocytes were divided into blank control group,X-ray irradiation group(X-ray group),X-ray irradiation+microRNA(miRNA)-134-5p inhibitor group(X-inhibitor group)and X-ray irradiation+miRNA-134-5p inhibitor negative control group(X-NC group).H9C2 cardiomyocytes were irradiated with 6 Gy X-ray,and the changes of various indexes were detected 48 h after irradiation.Cell viability was detected by cell counting kit 8 assay.The apoptosis rate was detected by flow cytometry and Hoechst 33342 staining.The level of reactive oxygen species(ROS)in cells was detected by DCFH-DA fluorescence probe.The mitochondrial membrane potential was detected by JC-1 method.The activity of superoxide dismutase(SOD)and the level of malondialdehyde(MDA)in cells were measured by kits.The expression of miRNA-134-5p was detected by quantitative polymerase chain reaction.The protein expression of brain-derived neurotrophic factor(BDNF),protein kinase B(Akt),phosphorylated Akt(p-Akt),Bcl2 and Bax was detected by Western blotting.Results Compared with the blank control group,in the X-ray group the levels of ROS and MDA were significantly increased,the activity of SOD was significantly decreased,the decreased percentage in mitochondrial membrane potential was significantly increased,the number of micronuclei of DNA damage was significantly increased,and the apoptosis rate was significantly increased(all P＜0.01).Compared with the X-ray group,all the indexes of the X-inhibitor group were reversed(P＜0.05 or P＜0.01),while there was no significant difference in the above parameters in the X-NC group(all P＞0.05).Compared with the blank control group,the X-ray group had a significant increase in the miRNA-134-5p level and significant reductions in the protein level of BDNF,Bcl2/Bax ratio,and p-Akt/Akt ratio(all P＜0.01).Compared with the X-ray group,the X-inhibitor group had a significant reduction in the level of miRNA-134-5p and significant increases in the protein level of BDNF,Bcl2/Bax ratio,and p-Akt/Akt ratio(all P＜0.01),and there was no significant difference in all parameters in the X-NC group(all P＞0.05).Conclusion X-ray irradiation can induce oxidative stress,mitochondrial damage,and DNA damage,eventually leading to apoptosis in rat cardiomyocytes,and the mechanism may involve miRNA-134-5p/BDNF/Akt signaling pathway.

Objective:To explore the long-term effects of intravascular ultrasound (IVUS) guidance on patients with acute coronary syndrome (ACS) undergoing drug-eluting stents (DES) implantation.Methods:Data used in this study derived from ULTIMATE trial, which was a prospective, multicenter, randomized study. A total of 1 448 all-comer patients were enrolled between 2014 August and 2017 May. Primary endpoint of this study was target vessel failure (TVF) at 3 years, including cardiac death, target-vessel-related myocardial infarction, and clinically-driven target vessel revascularization.Results:ACS was present in 1 136 (78.5%) patients, and 3-year clinical follow-up was available in 1 423 patients (98.3%). TVF in the ACS group was 9.6% (109/1 136), which was significantly higher than 4.5% (14/312) in the non-ACS group (log-rank P=0.005). There were 109 TVFs in the ACS patients, with 7.6% (43/569) TVFs in the IVUS group and 11.6% (66/567) TVFs in the angiography group (log-rank P=0.019). Moreover, patients with optimal IVUS guidance were associated with a lower risk of 3-year TVF compared to those with suboptimal IVUS results (5.4% (16/296) vs. 9.9% (27/273),log-rank P=0.041). Conclusions:This ULTIMATE-ACS subgroup analysis showed that ACS patients undergoing DES implantation were associated with a higher risk of 3-year TVF. More importantly, the risk of TVF could be significantly decreased through IVUS guidance in patients with ACS, especially in those who had an IVUS-defined optimal procedure.

Objective:To evaluate the relationship between pelvimetric parameters and surgical difficulty in robot-assisted total mesorectal excision (TME) performed by experienced colorectal surgeons, and to build a nomogram model.Methods:This was a retrospective observational study. The inclusion criteria were as follows: (1) tumor within 10 cm of the anal verge; (2) cancer confirmed by pathological examination of the postoperative specimen; (3) preoperative complete magnetic resonance imaging (MRI) data available; (4) depth of tumor invasion T1-3; (5) circumferential resection margin assessed as negative by MRI; and (6) R0 resection achieved. The exclusion criteria comprised (1) history of pelvic fractures; (2) history of pelvic surgery; and (3) emergency required because of tumor-related intestinal obstruction and/or perforation. Application of above criteria yielded 82 patients who had undergone robot-assisted total mesorectal excision of mid and low rectal cancer in the Department of Colorectal Surgery of the First Affiliated Hospital of Zhengzhou University from January 2021 to December 2022 (modeling group). Additionally, data of 35 patients with mid and low rectal cancer who had undergone robotic-assisted TME at the same center in 2023 January–August were collected for validation of the model (validation group). The following 13 pelvic parameters were studied: pelvic inlet diameter, pelvic outlet diameter, pubic tubercle height, sacral height, sacral depth, interspinous distance, inter-tuberosity distance, lateral mesorectal span, anterior-posterior mesorectal span, anterior mesorectal thickness, posterior mesorectal thickness, rectal area, and mesorectal area. Operating time was used as an indicator of the degree of surgical difficulty, this being defined as the time from the start of skin incision to the end of abdominal closure. Variables related to the duration of surgery were subjected to univariate and multivariate logistic regression analyses to identify factors associated with the difficulty of TME, after which a nomogram for predicting the difficulty of the procedure was established. We constructed receiver operating characteristic and calibration curves to validate the predictive power of nomogram. Furthermore, data from the validation group were used for external validation of the model.Results:The model group comprised 82 patients, including 54 men and 28 women of median age 61.0 years. The median body mass index (BMI) was 23.7 kg/m 2, median distance between the tumor and anal verge 6.1 cm, and median tumor diameter 4.5 cm. Fourteen of these patients had received preoperative adjuvant therapy and 12 had a history of abdominal surgery. There were 35 patients (24 men and 11 women) of median age 64.0 years in the validation group. Their median BMI was 23.7 kg/m 2 and median distance between the tumor and anal verge 6.3 cm. Multivariable analyses of the model group showed that BMI (OR=1.227, 95%CI: 1.240–1.469, P=0.026), distance between the tumor and anal verge (OR=0.733, 95%CI: 0.562–0.955, P=0.022), and interspinous distance (OR=0.468, 95%CI: 0.270–0.812, P=0.007) were independent predictors of surgical difficulty. We then built and validated a predictive nomogram based on the above three variables (AUC=0.804, 95%CI: 0.707–0.900). Calibration curves showed that the S:P in this model was 0.987 and the C-index 0.804. Area under the receiver operating characteristic curve of the predictive model in the validation dataset was 0.767 (95%CI: 0.606–0.928). Conclusion:MRI-based measurements of pelvic parameters are associated with difficulty of performing robot-assisted TME for mid and low rectal cancer. Our nomogram model constructed based on measurements of pelvic parameters has a good predictive ability.

Objective:To evaluate the relationship between pelvimetric parameters and surgical difficulty in robot-assisted total mesorectal excision (TME) performed by experienced colorectal surgeons, and to build a nomogram model.Methods:This was a retrospective observational study. The inclusion criteria were as follows: (1) tumor within 10 cm of the anal verge; (2) cancer confirmed by pathological examination of the postoperative specimen; (3) preoperative complete magnetic resonance imaging (MRI) data available; (4) depth of tumor invasion T1-3; (5) circumferential resection margin assessed as negative by MRI; and (6) R0 resection achieved. The exclusion criteria comprised (1) history of pelvic fractures; (2) history of pelvic surgery; and (3) emergency required because of tumor-related intestinal obstruction and/or perforation. Application of above criteria yielded 82 patients who had undergone robot-assisted total mesorectal excision of mid and low rectal cancer in the Department of Colorectal Surgery of the First Affiliated Hospital of Zhengzhou University from January 2021 to December 2022 (modeling group). Additionally, data of 35 patients with mid and low rectal cancer who had undergone robotic-assisted TME at the same center in 2023 January–August were collected for validation of the model (validation group). The following 13 pelvic parameters were studied: pelvic inlet diameter, pelvic outlet diameter, pubic tubercle height, sacral height, sacral depth, interspinous distance, inter-tuberosity distance, lateral mesorectal span, anterior-posterior mesorectal span, anterior mesorectal thickness, posterior mesorectal thickness, rectal area, and mesorectal area. Operating time was used as an indicator of the degree of surgical difficulty, this being defined as the time from the start of skin incision to the end of abdominal closure. Variables related to the duration of surgery were subjected to univariate and multivariate logistic regression analyses to identify factors associated with the difficulty of TME, after which a nomogram for predicting the difficulty of the procedure was established. We constructed receiver operating characteristic and calibration curves to validate the predictive power of nomogram. Furthermore, data from the validation group were used for external validation of the model.Results:The model group comprised 82 patients, including 54 men and 28 women of median age 61.0 years. The median body mass index (BMI) was 23.7 kg/m 2, median distance between the tumor and anal verge 6.1 cm, and median tumor diameter 4.5 cm. Fourteen of these patients had received preoperative adjuvant therapy and 12 had a history of abdominal surgery. There were 35 patients (24 men and 11 women) of median age 64.0 years in the validation group. Their median BMI was 23.7 kg/m 2 and median distance between the tumor and anal verge 6.3 cm. Multivariable analyses of the model group showed that BMI (OR=1.227, 95%CI: 1.240–1.469, P=0.026), distance between the tumor and anal verge (OR=0.733, 95%CI: 0.562–0.955, P=0.022), and interspinous distance (OR=0.468, 95%CI: 0.270–0.812, P=0.007) were independent predictors of surgical difficulty. We then built and validated a predictive nomogram based on the above three variables (AUC=0.804, 95%CI: 0.707–0.900). Calibration curves showed that the S:P in this model was 0.987 and the C-index 0.804. Area under the receiver operating characteristic curve of the predictive model in the validation dataset was 0.767 (95%CI: 0.606–0.928). Conclusion:MRI-based measurements of pelvic parameters are associated with difficulty of performing robot-assisted TME for mid and low rectal cancer. Our nomogram model constructed based on measurements of pelvic parameters has a good predictive ability.