Thoracic ossification of ligament flavum (TOLF) is a pathological process of heterotopic bone formation from ligamentum flavum tissue, which is the most common cause of thoracic spinal stenosis and thoracic myelopathy. Imaging examination is the predominant measure for localization and qualitative diagnosis for TOLF. Various TOLF classification systems have been reported currently, based on its morphology, distribution, configuration of compressed spinal cord or its association with peripheral tissue structures. However, there has been no unified classification due to confusing clinical applications. Therefore, we conducted a review to summarize TOLF classification systems and to evaluate the reliability of these classification systems and the diagnostic accuracy of various imaging modalities. As demonstrated in literatures, the diagnostic accuracy of radiography and the reliability of related classification were low. CT-based Sato classification (lateral, extended, enlarged, fused, tuberous) and Kuh classification (unilateral, bilateral, bridging), MRI-based Kuh classification (round, beak) and Chen Zhongqiang classification (isolated, skipping, continuous), Muthukumar classification combined with dural ossification (Tram track sign, Comma sign) elaborated ossification characteristics from different angles and dimensions. These classification systems were clinically significant in pathogenesis implication, risk assessment, treatment guidance and prognosis judgement, which showed high diagnostic accuracy and reliability. Combining multi-dimension and multi-level parameters of CT and MRI will play an important role in the diagnosis, treatment and new classification research of TOLF.

Objective: To understand the characteristics of sexual partners and the influence of having multiple sexual partners on substance use among young male students man who have sex with men (MSM) in China, and to provide scientific basis for the prevention and control of HIV/AIDS among young MSM students. Methods: A mixed recruitment method of snowball sampling and respondent driven sampling was used to recruit young MSM students in Beijing and Tianjin, and a questionnaire survey was conducted among 220 participants from November to December 2019. Chi-square test and generalized linear model multi-factor Logistic regression were used to analyze the influencing factors of substance use before sexual behavior. Results: The average age of them was (22.39±2.57) years old, 84.5% of them were students, the average age of first sexual behavior was (18.83±2.45) years old, 44.1% of them had two or more sexual partners (including fixed sexual partners, temporary sexual partners and commercial sexual partners), 22.7% had more than one male fixed partner. After adjusting for age and education, having multiple sexual partners was risk factor for drinking alcohol before sex (aOR=2.97) or substance abuse (aOR=2.39). Having male temporary sexual partner was an risk factor in substance use before sexual behavior(OR=4.10). Conclusion The characteristics of sexual partners among young MSM students are complex, and the proportion of multiple sexual partners is high. Having fixed single sexual partner can reduce the risk of substance use before sexual behavior. AIDS prevention education for young MSM students should be further strengthened.

Objective To compare the function recovery of multiple injuries combined with floating knee joint injury and simple knee joint injury,and to analyze the risk factors.Methods A retrospective case control study was conducted to analyze the clinical data of 41 patients with multiple injuries combined with Blake and McBryde Ⅱ A floating knee injury admitted to Xijing Hospital of Air Force Medical University from June 2011 to June 2017.There were 26 males and 15 females,aged 18-76 years,with an average of 34.5 years.There were 25 patients with simple knee joint injury and and 16 patients with multi-joint combined injury involving knee joint and ipsilateral hip joint or ankle joint injury.Surgical fixation was performed in different parts by external fixation,intramedullary nail and plate screw fixation.According to the Kalstr(o)m and Olerud functional evaluation criteria,the excellent and good rate of postoperative functional recovery was compared between the two groups.The surgical fixation methods of the two groups were compared.Logistic regression analysis was performed on the influencing factors of functional recovery.Results The patients were followed up for 1-7 years,with an average of 3 years.The excellent and good rate of overall functional recovery in the two groups was 68％,and the rate was 84％ in simple knee injury group and 44％ in multi-joint combined injury group (P ＜ 0.01).There was no significant difference in the ratio of intramedullary nail and plate screw fixation between the two groups (P ＞ 0.05),while the proportion of the external fixation in the multi-joint combined injury group [31％ (5/16)] was significantly higher than that in the simple knee joint injury group [16％ (4/25)] (P ＜ 0.05).Logistic regression analysis showed that the rate of external fixation was an independent factor affecting the postoperative function (OR =0.15,P ＜ 0.01).Conclusions The postoperative function in multi-joint injury patients is poorer than in the single joint injury patients.The higher rate of using external fixation in multi-joint injury patients is a risk factor.For Blake and McBryde Ⅱ A floating knee injury combined with multi-joint injury,less external fixation should be used,so as to improve the postoperative function.

Ossification of posterior longitudinal ligament (OPLL) and ossification of ligamentum flavum (OLF) are clinically common heterotopic ossification diseases, which are the main causes of cervical and thoracic spinal stenosis and spinal cord injury. In some cases, OPLL and OLF may involve multiple spinal sites, individually or concurrently, increasing the difficulty of clinical diagnosis and treatment. This review initially attempts to define this specific ossification phenomenon as Tandem ossification of intraspinal ligaments (TOIL). It refers to a kind of severe spinal ligament ossification diseases caused by multiple factors, that OPLL and OLF occur alone or in combination at two or more sites of the cervical, thoracic, or lumbar spine with five or more ossified segments, progressively compressing the spinal cord or nerves, thereby resulting in a series of complex clinical symptoms. The prevalence of TOIL remains unknown, but its clinical detection rate is relatively high, and the most common TOIL is cervical OPLL combined with thoracic OPLL or/and OLF. Moreover, occurrence and development of TOIL involve many factors and its definitepathogenesis is not clear. Damage of upper and lower motor neurons can occur simultaneously in TOIL patients so that their clinical symptoms and signs often interfere with each other. TOIL has various forms, complex imaging features, and no uniform diagnostic and localization diagnostic criteria, which may easily lead to missed diagnosis and misdiagnosis. It is recommended that TOIL is identified by the typical symptoms and signs as the basis, CT three-dimensional reconstruction and MRI signs as the reference, and combination of the possible risk factors and clinical experience. Currently, surgical decompression for responsible lesions is the only effective treatment for symptomatic TOIL. However, domestic and foreign scholars still have great arguments on the optimal surgical strategy of TOIL. No consensus has been reached on how to determine the operating segment and the extent of decompression, which surgical approach and technique to be adopted, and when to select staged or one-stage combined surgery. Therefore, this review summarizes and discusses the current status and progress of the clinical characteristics and surgical strategies of TOIL through searching the relevant literature, to provide a reference for clinicians to diagnose and treat TOIL.

Objective: To identify the characteristics of social network and the association between ego-centric network and HIV status among young MSM Chinese students. Methods: The cross-sectional study was conducted in Chongqing, Tianjin, Harbin and Xi an city from April to December 2017 and from March to May 2018. A mixed recruitment method of snowball sampling and RDS approach was used to recruit participants who reported information on social network and received HIV test. The Multiple Regression Analysis method was used to for the analysis of association between ego-centric social network and HIV status of men who have sex with men (MSM) among young students. Results: The sample included 547 participants who nominated 1 088 social partners in total with average age of 13 to 60 years old. The MSM with different sexual orientation from their social members (aOR=0.38), embedded in a large network (aOR=0.63), with a high individual betweenness centrality (aOR=0.27) were at lower risk of HIV-positive status; while MSM who differed greatly in education level with their social members(aOR=1.60), existed in sexual networks(aOR=1.41), existed in the “risky networks” (aOR=1.88) , with high network density (aOR=1.91) and a high individual degree (aOR=4.10) had higher risk of HIV-positive status(P<0.05). Conclusion MSM with great difference in education level from social members, existed in sexual networks, with a large network density and a high degree were exposed to higher risk of HIV-positive status.

Objective:To analyze the prevalence and distribution characteristics of diffuse idiopathic skeletal hyperostosis (DISH) in hospitalized patients with thoracic ossification of the ligamentum flavum (TOLF).Methods:The clinical records of 132 consecutive TOLF patients from January 2018 to June 2019 were retrospectively studied. DISH was identified by the preoperative X-ray and CT and its prevalence was calculated. The prevalence of patients with different genders, different age groups and different ossification types was compared. The segmental distribution of DISH and the distribution in the upper (T 1-T 4), middle (T 5-T 8), and lower thoracic spine (T 9-T 12) were analyzed. Ossification degree of DISH was evaluated based on the Meta scoring system. The demographic characteristics (age, gender, BMI, etc.) were compared between DISH and non-DISH group. Results:Forty-nine patients was diagnosed as DISH with the prevalence of 37.1% in all included cases. The prevalence was about twice as high in male (46.3%) than in female (23.1%) ( χ2=8.806, P=0.003). The prevalence in the age groups of <40, 40-49, 50-59, 60-69 and ≥70 years was 20.0%, 28.0%, 34.4%, 44.0%, and 66.7%, respectively. The prevalence in long-segment TOLF patients (45.1%) was significantly higher than that in short-segment TOLF patients (24.0%) ( χ2=5.937, P=0.015). DISH most frequently affected T 8,9 levels (91.8%). The total number and mean number of ossified segments were 365 and 7.4, respectively. Ossification lesions in the upper, middle, lower thoracic spine accounted for 26.03%, 40.54%, and 33.15%, respectively. Grade I, grade II, and grade III ossification accounted for 21.4%, 28.5% and 50.1%, respectively. The mean age of the DISH group was older than the non-DISH group ( t=2.024, P=0.045). The proportion of male patients in the DISH group was significantly higher than that in the non-DISH group ( χ2=8.806, P=0.003). The average height and weight in the DISH group were significantly greater than those in the non-DISH group ( t=2.564, P=0.012; t=2.191, P=0.030), whereas no significant differences in BMI and constituent ratio of concurrent diabetes, cardiac disease, hypertension between two groups were observed. Conclusion:The prevalence of DISH in patients with TOLF is 37.1%. Male, elderly and long-segment TOLF patients are associated with higher prevalence. DISH frequently occurs in the middle and lower thoracic spine, and T 8,9 is the common affected segment. Ossification lesions may develop with age. Demographic characteristics of DISH group differ, to some extent, from those of non-DISH group.

Objective:To compare the safety and efficacy of the " step-up approach" versus the " step-jump approach" in treatment of infected pancreatic necrosis (IPN).Method:The clinical data of IPN patients who underwent step-up strategy or step-jump strategy treatment at the Department of Pancreatic and Biliary Surgery of the First Affiliated Hospital of Harbin Medical University from December 2018 to November 2022 were analyzed retrospectively. Propensity score matching (PSM) was done based on the nearest neighbor matching method (1: 1 ratio). After matching the baseline data (the caliper value was 0.01), a total of 62 patients with IPN were included, including 41 males and 21 females, aged (41.1±13.1) years old. Patients who were treated with the step-up strategy were included in the step-up group, while patients who were treated with the step-jump strategy were included in the step-jump group. There were 31 patients in each group after PSM, and the treatment effect of the two groups were compared.Results:Of the 62 patients with IPN, 43 received surgical intervention, and 19 were managed successfully using symptomatic anti-inflammatory treatment or percutaneous catheter drainage. The total hospitalization cost of patients in the step-jump group was significantly higher than that in the step-up group [122 000 (73 000, 179 000) yuan vs. 88 000 (46 000, 144 000) yuan, P=0.034]. The overall cure rate of IPN patients in the step-jump group was 93.5%(29/31). The 2 patients who died had type Ⅲ IPN. In the IPN patients in the step-up group were all cured, and the overall cure rate was 100%(31/31), with no death. There were no statistical differences between the two groups in the rates of death, postoperative complications, residual infection, debridement ≥2 times, and positive bacterial culture in blood or drainage fluid (all P>0.05). A total of 19.4% (12/62) patients had postoperative complications, including 4 patients with abdominal bleeding, 3 patients with new organ dysfunction, 2 patients with gastrointestinal bleeding, 2 patients with gastrointestinal fistula, and 1 patient with venous thrombosis in both lower limbs. Conclusion:Both the step-up treatment strategy and the step-jump treatment strategy were safe and effective for treatment of IPN patients.