Objective To observe the value of anatomical characteristics of femoral intercondylar notch of knee joint for predicting non-contact anterior cruciate ligament tear(NC-ACLT).Methods MRI data of knee joint of 55 patients with NC-ACLT(NC-ACLT group)and 55 controls(control group)were retrospectively analyzed.The parameters of intercondylar notch,including depth,width,depth/width ratio,opening width,opening width index,area and width of the femoral condyle's outer edge at the same level were measured between groups,and the types of intercondylar notch(type A,U and W)were recorded.Univariate and multivariate logistic regression analysis were used to screen the independent impact factors of NC-ACLT.Receiver operating characteristic curves were drawn,and the area under the curves(AUC)were calculated to evaluate the efficacy of each intercondylar notch parameter for predicting NC-ACLT.Results The depth and depth/width ratio of intercondylar notch in NC-ACLT group were both higher,while the opening width and opening width index of intercondylar notch in NC-ACLT group were both lower than those in control group(all P＜0.05).Multivariate logistic regression analysis revealed that the depth of intercondylar notch was an independent impact factors of NC-ACLT(P＜0.05).Taken 29.55 mm in depth of intercondylar notch,1.45 in depth/width ratio of intercondylar notch,21.15 mm in opening width of intercondylar notch and 0.29 in opening width index as the optimal cut-off value,respectively,the sensitivity of the above parameters for predicting NC-ACLT was 74.55％,58.18％,67.27％and 67.27％,the specificity was 69.09％,80.00％,61.82％and 78.18％,and the AUC was 0.720,0.713,0.652 and 0.710,respectively.Conclusion The anatomical characteristics of femoral intercondylar notch of knee joint could be used to predict NC-ACLT.The depth,depth/width ratio,opening width and opening width index of intercondylar notch could be used as predictive indicators.

Objective: To investigate the snoring status of school-aged children in Beijing and explore the association of snoring and academic performance. Methods: A total of 7 925 children aged from 6 to 14 were selected from 15 primary and middle schools at 7 districts (Xicheng, Chaoyang, Changping, Shunyi, Fangshan, Huairou and Mentougou) in Beijing in 2015, using multi-stage stratified cluster random sampling method. The recruited children were asked to complete the Pediatric Sleep Questionnaire (PSQ) and a questionnaire related to sleep behavior. The multiplelogistic regression was used to analyze the association of snoring and academic performance. Results: A total of 794 (12.44%) children showed a decline in academic performance among 6 383 eligible respondentsfor data analysis. 580 (9.08%) children with snoring was identified, of which 333 and 247 were in frequency of 1-2 times per week and frequency of ≥3 times per week, respectively; 357, 170 and 53 were in snoring grade Ⅰ, grade Ⅱ and grade Ⅲ, respectively. Compared with the children without snoring, the OR (95%CI) for children with 1-2 times per week and ≥3 times per week was 1.363 (1.000-1.857) and 1.605 (1.135-2.269), respectively; and the OR (95%CI) for children with grade Ⅰ, grade Ⅱ and grade Ⅲ of snoring was 1.226 (0.893-1.683), 1.595 (1.062-2.397) and 2.31 (1.17-4.565), respectively. Conclusion There is a statistical relationship between snoring and the decline of academic performance. The decline of academic performance positively associated with increased frequency and grade of snoring.

Objective: To investigate the snoring status and related family factors of children from 3 to 14 years old in Beijing. Methods: From May to July, 2015, data of children from 3 to 14 years old were obtained from a status survey from 7 districts(Xicheng, Chaoyang, Changping, Shunyi, Fangshan, Huairou and Mentougou) in Beijing. A total of 11 420 children from 25 primary and middle schools were randomly selected. Pediatric Sleep Questionnaire (PSQ) and a self-administered questionnaire were carried out for the adopted children. Self-administered questionnaire included the snoring related family factors. Logistic regression was used to estimate the odd ratio(OR) with 95% confidence intervals for variables. Results: A total of 9 198 children meet the inclusion criteria and are analyzed in the study, of whom 901 (9.80%) were found with snoring behavior. The incidence of boys is higher than girls. Obese children take higher risk of snoring. Compared with younger children (≤6 years old), older children (≥12 years old) have a significantly lower risk of snoring (OR=0.464, 95%CI 0.368-0.585). There is no statistical association between full-term infants, infant feeding pattern, parental cigarette smoking and child snoring.The children with family history of snoring have a significantly higher risk of snoring occurrence. The educational background of mother is statistically related to children snoring (OR=1.241, 95%CI 1.058-1.457). Conclusions The incidence of children snoring in Beijing is 9.80%, male gender, obesity, and young age are all risk factors for children snoring. There is a significantly statistical relationship between snoring and related family factors, such as family snoring history and education experience.

Objective: To investigate the sleep quality of children in Beijing and to analyze the related factors. Methods: The data were collected from the survey of 3-14 years old children in 7 urban districts of Beijing in 2015. By using multi-stage stratified cluster random sampling method, 26 kindergartens and primary and secondary schools in 7 districts and counties, including Xicheng, Chaoyang, Changping, Shunyi, Fangshan, Huairou and Mentougou, were randomly selected, with a total of 11 420 children. Children′s sleep status was investigated with Children′s Sleep Questionnaire (PSQ), and the proportion of children with sleep quality problems when the PSQ score was greater than 7. Various sleep related factors were investigated with self-made questionnaire. A multilevel model was used to analyze the relationship between PSQ score and related factors. Results: The average PSQ score of the children was 3.60±2.69. The proportion of children with sleep quality problems was 8.87%(816/9 198). Multilevel model analysis showed that the younger the children, the higher the PSQ score (<6 years old vs. 6~12 years old vs. >12 years old: 3.94±2.58 vs. 3.58±2.66 vs. 3.30±2.84, F=33.015, P<0.001); male PSQ score higher than female (3.89±2.75 vs. 3.30±2.60, t=10.560, P<0.001); and snoring, obesity, father/mother snoring, playing games before bed, surfing the internet, eating and other factors were statistically related to PSQ. Conclusions Sleep quality of children in Beijing should not be neglected, especially preschool children with high PSQ scores. Parents should pay attention to children′s snoring problems and try to reduce some pre-sleep behaviors that may affect sleep quality.