Thoracic ossification of ligament flavum (TOLF) is a chronic progressive disease presenting the heterotopic ossification of the ligamentum flavum of the thoracic spine, which leads to a series of symptoms and signs of thoracic spinal cord, nerveor vascular compression, with a high incidence in East Asian countries such as China and Japan. The pathology of TOLF is endochondral ossification in nature and surgical intervention is currently the only effective treatment due to conservative treatment does not work. The older age, the insidious onset, the various clinical manifestations of TOLF patients make the localization diagnosis and surgery management difficult and even bring about the high incidence of postoperative complications. Therefore, it is particularly important to study the mechanism of osteogenic differentiation of TOLF to find a way of early diagnosis and prevention. A variety of factors related to osteogenic differentiation of TOLF have been found, such as genetics, mechanical stimuli, molecular biological factors, metabolic and trace element abnormalities and so on. Moreover, molecular signaling pathways play a crucial role in regulating cell proliferation and directed differentiation. Therefore, this article reviews the confirmed relevant signaling pathways in the process of ligamentum flavum ossification, including bone morphogenetic protein (BMP) signaling pathway, mitogen-activated protein kinase (MAPK) signaling pathway, Wnt signaling pathway, Notch signaling pathway, STAT3 signaling pathway and other signaling pathways and factors, and also summarizes the promotion and inhibition of these signaling pathways in the osteogenic differentiation of ligamentum flavum cells, aiming at establishing a basis for the further research of the molecular biological mechanism of TOLF, and providing a possible direction for exploration of effective preventive and therapeutic targets.

In order to provide more practicable and convenient continuing medical education for orthopedic surgeons in primary hospitals and expand the academic influence of expert lecturers and host hospitals in the region, our department hosted nine short-term training courses of orthopedic surgery jointly with primary hospitals, which lasted for 1 to 1.5 days on weekends from June 2001 to October 2017, with expert lectures as the main form. Traumatic orthopedics was the main topic, and most expert lecturers were orthopedic experts from famous hospitals within the province and the whole country, as well as the experts from the host hospital. More than 1200 orthopedic and surgical physicians in local districts and counties participated in the training, and excellent social effect has been achieved. For short-term orthopedic training jointly held with hospitals in prefecture-level cities, the topic of training should be carefully selected, and duration of the training and number of lecturers should be controlled, so as to achieve satisfactory social effects under the premise of low cost of administrative resources.

Objective:To compare a novel kind of anatomical locking plate versus proximal humeral internal locking system (PHILOS) in the treatment of proximal humerus fractures.Methods:A retrospective study was performed in the 35 patients with proximal humerus fracture who had been operatively treated at Department of Orthopedics, The Third Hospital of Peking University from January 2020 to June 2021. They were 13 males and 22 females, aged from 24 to 83 years (average, 56.7 years). Of them, 14 were fixated by the novel anatomical locking plate and 21 by PHILOS. The 2 groups were compared in terms of gender, age, fracture type, operation time, intraoperative blood loss, hospital stay, University of California (UCLA) shoulder scores and Disability of Arm Shoulder and Hand (DASH) scores for the upper limb dysfunction at one month after operation and at the last follow-up, and postoperative complications.Results:There was no significant difference in the preoperative general data between the novel plate group and the PHILOS group, showing comparability between them ( P>0.05). All the patients were followed up for 6 to 21 months (mean, 11.3 months). In the novel anatomical plate group, the operation time was (83.9±29.2) min, the intraoperative blood loss was (36.4±27.1) mL, the hospital stay was (2.3±1.1) d, the UCLA score and DASH score at one month after operation were (20.1±4.7) points and (55.5±19.1) points, the UCLA score and DASH score at the last follow-up were (28.5±4.6) points and (25.1±24.4) points, respectively; 2 patients developed complications after operation. In the PHILOS group, the operation time was (85.0±38.8) min, the intraoperative blood loss was (62.9±46.8) mL, the hospital stay was (2.4±0.9) d, the UCLA score and DASH score at one month after operation were (21.0±3.8) points and (49.6±23.7) points, and the UCLA score and DASH score at the last follow-up were (28.0±5.1) points and (19.1±17.3) points, respectively; 3 patients developed complications after operation. There was no significant difference in all the above items between the 2 groups (all P>0.05). Conclusion:In the treatment of proximal humerus fractures, the novel anatomical locking plate is a feasible internal fixator because it is comparable to PHILOS in fine efficacy, good fracture healing, and satisfactory functional recovery of the shoulder joint.

Spinal metastases may cause pain,pathological fracture and/or neurological symptoms.The most common treatment of spinal metastases is conservative therapy.Surgical intervention is necessary when there are pathological and/or neurological deficits.Total en bloc spondylectomy (TES) has lower local recurrence rate and may be applicable to a patient with single metastatic tumor and a long survival expectancy,While debulking surgery is less risky and higher recurrence rate.Conventional radiotherapy is a kind of effective supplement to reduce the local recurrence rate in spinal metastases.However,the local dose is often failed to reach the effective dose because of the close connection of tumor and spinal cord and it is less effective for relatively radioresistant histologies.With the development of radiotherapy technology,spinal radiotherapy has become increasingly accurate to avoid of spinal cord injury.In addition,conventional radioresistant tumors has become treatable with high-dose stereotactic body radiotherapy (SBRT).At the same time,SBRT is also an important basis for the implementation of separation surgery of spinal metastases.Separation surgery is to separate the tumor and dura and achieve circumferential decompression and stabilization through posterior approach.As a result,a high-dose SBRT can be performed because of the small interspace to protect the spinal cord,which greatly reduces the local recurrence rate.Compared with TES,separation surgery combined with high-dose radiotherapy not only reduces the difficulty of surgery,but also has a good local control rate,which is a relatively "minimally invasive" strategy.Separation surgery is particularly suitable for patients with high-grade epidural spinal cord compression and moderately sensitive or insensitive to radiotherapy.Although the concept of separation surgery has been proposed for several years,only a few applications have been reported in foreign literature and fewer in domestic literature.This article aims to summarize the relevant concepts and clinical applications of separation surgery in spine metastases and to provide a reference for the treatment of spinal metastases.

Objective:To explore the relevant prognostic factors and construct a nomogram to predict the relapse-free survival of cervical chordoma.Methods:Data of 48 patients with cervical chordoma treated by operation from November 1994 to June 2018 were retrospectively analyzed, including 28 males and 20 females, aged 48.5±15.4 years (range 5-70 years). Data extraction comprised patients age, gender, Karnofsky performance status scale (KPS), duration of preoperative symptoms, location, involved segments, preoperative Frankel score, diagnostic biopsy method, adjuvant radiotherapy, surgical option and complications. Follow-up was conducted at 3, 6, 12 months after surgery and annually, X-Ray/CT/MRI were used to evaluate the progress of disease. Univariate analysis was performed using Kaplan-Meier survival analysis and Log Rank test to identify prognostic factors relevant to relapse-free survival, and multivariate Cox regression analysis was used in multivariate analysis, then R 3.6.2 was used to construct a nomogram.Results:Mean follow-up time was 66.6±51.1 months (range 14-228 months), 35 cases relapsed up to follow-up time, the cumulative 1-year, 3-year and 5-year relapse-free survival were 70.8%, 42.1% and 30.9%. Univariate analysis showed that diagnostic biopsy method ( P=0.016), adjuvant radiation therapy ( P=0.027), surgical option ( P<0.001) were relevant to relapse-free survival of cervical chordoma. Multivariate Cox regression analysis showed that surgical option (intralesional resection after extracapsular separation vs. directly intralesional resection), HR=0.209, 95% CI (0.076, 0.575) had significant impacts on relapse-free survival of cervical chordoma. A nomogram with c-index of 0.760 to predict 1-year, 3-year and 5-year relapse-free survival was conducted basing on age, gender, location, involved segments, diagnostic biopsy method, adjuvant radiation therapy, surgical option. Conclusion:Aspiration biopsy, intralesional resection after extracapsular separation and adjuvant radiation therapy could prolong the relapse-free survival of cervical chordoma. The nomogram in this study could predict 1-year, 3-year and 5-year relapse-free survival of cervical chordoma with relatively good accuracy.

Objective To observe the effect of different synovial cell secretions on chondrocytes after LPS-induced inflammation,and to explore the mechanism of two synovial cell secretions causing cartilage damage in the progres-sion of KOA disease.Methods Two kinds of synovial cells were co-cultured at 1∶4 and LPS-induced inflamma-tion.The supernatant and exocrine were extracted,and then the normal and LPS-induced inflammation were extrac-ted.The human cartilage tissue obtained during the operation was isolated and cultured into chondrocytes,which were divided into five groups:the first group was added with FLS secretion,the second group was added with nor-mal FLS secretion,the third group was added with secretion after co-culture of two kinds of synovial cells,the fourth group was added with inflammatory MLS secretion,and the fifth group was added with inflammatory FLS se-cretion.CCK-8 was used to detect the viability of chondrocytes in each group.TNF-α,IL-1β,IL-6 level in the su-pernatant of chondrocytes in each group was detected by ELISA.The protein expression of TLR4,NF-κB,IkK,IκB,ADAMTS5 in chondrocytes of each group was detected by Western blot method.Results CCK-8 showed that the activity of chondrocytes in the three groups of inflammatory secretions decreased compared with the secretions from normal synovial cells(P＜0.05);ELISA showed TNF-α,IL-1 β,IL-6 level in the supernatant of group Ⅲ,Ⅳ and V was higher than that of group Ⅰ and Ⅱ(P＜0.05),TNF-α,IL-1 β,IL-6 level in group Ⅲ was higher than that in group Ⅳ but lower than that in group Ⅴ(P＜0.05).Western blot showed the protein expression of TLR4,NF-κB,IkK,IκB,ADAMTS5 in chondrocytes of group Ⅲ,Ⅳ and Ⅴ was higher than that in group Ⅰ and Ⅱ(P＜0.05),the protein expression of TLR4,NF-κB,IkK,IκB,ADAMTS5 in group Ⅲ was higher than that in group Ⅳbut lower than that in group Ⅴ(P＜0.05).Conclusion Two kinds of synovial cell-derived secretions after LPS-induced inflammation can regulate cartilage TLRs/NF-κB signal pathway,causing cartilage inflammation.The in-flammatory effect of MLS secretion is stronger than that of FLS secretion,but the inflammatory effect of MLS secre-tion under two co-cultures is weaker than that of MLS secretion alone.

Distal junctional problem (DJP) is one of the severe complications after spinal correction, fixation and fusion. As the number of patients receiving spinal surgery increased recently, the incidence of DJP also increased dramatically. Compared with proximal junctional problem, the incidence of DJP is low. However, the clinical symptoms are severe, and the rate of surgical revision is high in patients with distal junctional problems. DJP include distal junctional kyphosis (DJK) and distal junctional failure(DJF). The definition of DJK is confusing, however, and the most commonly used was that the distal junction Angle at the last follow-up was greater than 10° and increased by 10° compared with that before surgery. There are 6 DJF modes: progressive loss of lumbar lordosis,acute wedging in the disc below the instrumentation, fracture of LIV, osteoporotic fracture below the long rigid fixation, failure of the instrumentation at LIV, spinal stenosis and or segmental instability underneath the instrumentation. Possible risk factors for DJP include weight, age, type of spinal deformity, osteoporosis, choice of LIV, hip disease, deformity location, surgical approach, surgical procedure, fusion segments, fixation devices, LIV at L5, fixed to S1 with no iliac screws, poor restoration of spinal alignment, et al. Currently, there are some controversies in DJP, mainly including the incidence, risk factors whether needs to and how to revise. The review intends to conduct a simple literature review of the current DJP diagnostic criteria, incidence, risk factors, and other research progress, in order to improve the understanding of the distal junction problem.

Objective:To evaluate the effect of 3D printed models assisted teaching method on clinical teaching of hip revision and improve the teaching quality.Methods:Fifty students who were in the standardized training for surgical specialty from Peking University Third Hospital were divided into a control group and an experimental group, with 25 students in each group. The control group was taught by traditional methods, while the experimental group was taught by 3D printed models. After the training, professional theory test and teaching evaluation questionnaire survey were conducted among the members of the two groups, and statistical analysis was made on the students' professional theory test scores, learning interests and teaching satisfaction. SPSS 18.0 was used for t test. Results:The theoretical scores of the experimental group [(84.60±5.76) points] were higher than those of the control group [(78.20±6.90) points], and the difference was statistically significant ( P<0.05). The teaching satisfaction and learning interest of the experimental group were both better than those of the control group [(4.72±0.46) vs. (4.28±0.61), (4.76±0.44) vs. (4.28±0.54)], with statistically significant differences ( P<0.05). Conclusion:The 3D printed model assisted teaching can effectively deepen students' understanding of hip joint structure, improve the teaching quality, and enhance their enthusiasm and initiative in learning.

Osteoporotic vertebral compression fracture (OVCF) is the most common complication of spinal osteoporosis, mostly occurring in thoracolumbar segment, which can cause acute and chronic pain at the fracture site and loss of vertebral height, and can lead to progressive kyphosis. For kyphosis caused by old OVCF, open surgery such as anterior or posterior decompression and fusion, internal fixation and osteotomy can improve local sequence and achieve satisfactory kyphotic correction which is difficult to complete in percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty (PKP), and reconstruct the sagittal balance. Due to the older age of OVCF patients, some of them have poor general conditions. In addition, osteoporosis leads to increased vertebral fragility, which increases the risk of surgery and postoperative internal fixation failure. The anterior approach presents some problems including a complex approach and poor mechanical stability. At present, most studies focus on posterior surgery. Due to the limitation of kyphosis correction by decompression and fixation alone, osteotomy is often required to correct kyphosis. In cases of old OVCF with kyphosis, the screw holding capability decreases due to the decrease of bone mineral density. Additionally, once the screw loosens, the orthopedic effect is inevitably affected. To enhance pedicle screws, most studies have utilized bone cement to increase the axial pullout force of the vertebral body and improve screw stability. The selection from different osteotomy methods is a critical determinant in achieving favorable surgical outcomes for patients.

Objective:To explore the clinical feasibility and effectiveness of using 3D printed porous titanium-alloy prosthesis to repair aseptic large bone defects in the limbs.Methods:A retrospective analysis was performed on 13 patients with aseptic bone defects of long limbs treated with 3D printed porous titanium alloy prosthesis from December 2017 to December 2022, including 7 males and 6 females, aged 52.6±11.5 years (range, 35-72 years). The bone defect locations included 2 humerus, 1 radius, 5 femur, and 6 tibia. One patient suffered both femoral and tibial defects. All 13 patients suffered from bone nonunion due to internal fixation surgery, including 5 cases of hypertrophic nonunion and 8 cases of atrophic nonunion. The interval between internal fixation surgery and this treatment was 20.1±3.6 months (range, 16.5-26.6 months). The clinical treatment effect was evaluated through parameters such as gross observation, imaging evaluation, disability of arm shoulder and hand (DASH), lower extremity functional scale (LEFS), and patient satisfaction evaluation.Results:The length of bone defect after debridement in 13 patients was 11.7±4.5 cm (range, 6.0-20.6 cm), and the length of implant was 12.9±5.3 cm (range, 6.1-22.9 cm). Partial or complete weight-bearing began at 14.8±6.5 days (range, 2-22 days) after surgery. All 13 cases were followed up for 18.3±12.5 months (range, 13-58 months). The X-ray images showed that the prosthesis and the internal fixation were stable, and the new bone gradually grew gradually from the bone defect section and formed stable bone integration with the prosthesis surface, and no prosthesis displacement or fracture occurred. At the last follow-up, the DASH scores of 3 patients with upper limb bone defect were 8.9, 10.5, and 11.2 points, respectively, and the LEFS scores of 10 patients with lower limb bone defect were 49.6±5.9 points (range, 38-56 points). No significant subsidence or loosening of all prosthetics was observed. Patient satisfaction was 9.8±0.1 points (range, 9.6-9.9).Conclusion:After the application of 3D printed porous titanium alloy prosthesis to repair the aseptic large bone defect of the limbs, the patients can carry weight and function exercise in the early stage, and the function of the affected limbs can recover significantly, and the patients have high satisfaction.