Objective To explore the clinical efficacy of minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) for bilateral isthmic spondylolisthesis on lumbar spine in adolescents. Methods Twentyone patients with bilateral isthmic spondylolisthesis on lumbar spine who received MIS TLIF from February 2012 to April 2014 were enrolled. Fourteen male, aged from 15 to 20 years, 16.3 years on average and 7 female, aged from 14 to 20 years, 15.6 years on average. The clinical outcome after operation was analyzed according to the low back pain and leg pain after operation which analyzed by visual analog scale (VAS) and Oswestry dysfunction index (ODI). The bone fusion were also recorded after surgery by using CT scan reconstruction. Results All cases were followed up 23.7 months on average. The VAS scores of lower back pain preoperative and at the last followup was (8.4 ± 1.2) scores and (2.3 ± 0.8) scores, the scores of ODI preoperative and at the last followup was (72.6 ± 7.4) scores and (29.7 ± 5.3) scores, there were significant differences (P < 0.05). At the last followup, there was no instrument failure noted in all patients,18 patients had complete bone union, while nonfusion were 3 patients. Conclusions MIS TLIF not only have the characteristic of less invasive, but can significantly release clinical symptom and can obtain higher rate of bone union.

Objective To observe the efficacy of posterior atlantoaxial fusion for C1/C2 fractures combined with ponticulus posticus.Methods A retrospective case series review was performed on data of 12 cases of C1/C2 fractures combined with ponticulus posticus treated from January 2008 to January 2014.There were 7 males and 5 females,aged 35.5 (23.5-49.25) years.Three cases were diagnosed with C1 lateral mass fractures combined with other injury,seven type Ⅱ odontoid fractures,and two type Ⅲ odontoid fractures.Nine cases whose C1 pedicle height ≥4 mm in both sides underwent posterior C1-C2 screw-rod fixation and fusion,and three cases whose C1 pedicle height was ＜ 4 mm underwent posterior C1-C2 hook-screw fixation and fusion.Operation time,blood loss and complications were recorded.Variations in American Spinal Injury Association (ASIA) grade and Visual Analogue Scale (VAS) were compared before operation and at final follow-up.Position of internal implant,fracture healing and fusion were observed.Results Surgery was successful in all cases.Operation time was 145 (120-160) min,and blood loss was 200 (200-300)ml.No intraoperative injury to the vertebral artery injury,venous plexus,spine and nerve root occurred,and no cases showed ponticulus posticus after operation.Follow-up period was 24 (12-33) months.Postoperative imaging demonstrated satisfactory implant placement in all eases.Before operation,one case was rated as ASIA grade A,two as grade D and nine as grade E.One case was rated as ASIA grade A and 11 as grade E at the final follow-up.VAS was improved from preoperative 7 (6-8) points to 0(0-1) points at the final follow-up (P ＜ 0.05).Fracture healing and fusion were observed in all cases at the final follow-up.Conclusion Posterior atlantoaxial fusion for C1/C2 fractures combined with ponticulus posticus is a safe and effective procedure that can promote fracture union without increasing the risk of vertebral artery injury.

Finite element method (FEM) is a method to decompose a large complex problem into several small problems to solve it. With this method, multiple small elements can be used to simulate the real physical system, which greatly promotes the development of biomechanics. Biomechanics has always been a hot research direction in spine surgery, and the finite element method is also widely used in spine biomechanics. It can simulate the healthy spine on the computer and study the stress of normal spine in various states, so as to provide help for the study of basic stress of spine.It can simulate the spinal column of pathological changes and degenerative changes, and study its stress in various scenarios, so as to provide direction for the treatment of diseases. Different surgical methods can be simulated to study the stress of the spine and internal fixation after different surgical methods, so as to select the best surgical method for patients; At the same time, it can also simulate different implants and study the stress of different implants in vivo and in vitro, so as to provide guidance for the selection of intraoperative implants and the upgrading and optimization of implants.This paper mainly discusses the application and progress of finite element method in spine surgery, and provides more references for the future study of spine biomechanics and clinical treatment of spine surgery.

Objective To evaluate the necessity and clinical significance of multi-slice spiral CTA (MSCTA) in preoperative examination of complex craniocervical junction (CCJ) malformation.Methods Totally 30 patients of complex CCJ malformation were enrolled,among them 16 underwent routine CT and MRI before surgery (routine group),and the other 14 underwent MSCTA of head and neck after routine CT and MRI (CTA group).The anatomical relationship between the V3 segment of VA and the bone in CCJ was observed,and then individualized operation scheme was formulated,MSCTA data in preoperative CTA group was reconstructed.The operation time,intraoperative blood loss and complications were compared between the two groups.Results CCJ malformation and VA V3 segment variation showed obvious individual characteristics in CTA group.The average operation time was (182.86 ± 27.37)min,and the loss of intraoperative blood was (165.71 ± 42.19)ml.No obvious complications occurred,and the therapeutic effect was satisfactory during follow-up period.In routine group,the average operation time was (205.31± 29.86)min,the loss of intraoperative blood was (246.25 ± 155.22)ml.Vertebral artery injury occurred in 1 case during operation,then bleeding was controlled,and improvement was achieved during follow-up period.There was no significant difference of operation time between the two groups (t=1.878,P=0.057),while the loss of intraoperative blood in CTA group was less than that of routine group (t =2.136,P=0.042).Conclusion MSCTA is a reliable method to investigate the anatomy and variation of bone and blood vessels in CCJ.It is necessary to carry out MSCTA examination before operation in patients with complex CCJ malformation,so as to reduce the complications and avoid the risk of surgery.

Bionics came into being with the development of science and technology. Its content is mainly to imitate the characteristics of biology to design machinery or equipment from an engineering perspective to solve a series of needs in people's production and life. It has been widely applied in many fields such as military and medical areas. Based on the wide discussion of bionics, bionic science and orthopedic bionic therapy, the authors put forward a new concept of spinal trauma bionic therapy(STBT) and expound its concept and connotation, so as to provide a new idea for overcoming the difficulty in treatment of spinal trauma.

Objective:To establish the acute symptomatic osteoporotic thoracolumbar fracture (ASOTLF) classification system, and to examine the reliability and evaluate the effect of clinical application.Methods:A retrospective case series study was conducted to analyze the clinical data of 1 293 patients with osteoporotic thoracolumbar fracture(OTLF) admitted to Honghui Hospital from January 2016 to December 2018. There were 514 males and 779 females, aged 57-90 years [(71.4±6.3)years]. The T value of bone mass density was -5.0--2.5 SD [(-3.1±-0.4)SD]. According to the clinical symptoms a and fracture morphology, OTLF was divided into 4 types, namely type I(I occult fracture), type II(compressed fracture), type III (burst fracture) and type IV(unstable fracture). The type II was subdivided into three subtypes (type IIA, IIB, IIC), and the Type III into two subtypes (type IIIA, IIIB). of all patients, 75 patients (5.8%) were with type I, 500 (38.7%) with type II A, 134 (10.4%) with type IIB, 97 (7.5%) with type IIC, 442 (34.2%) with type IIIA, 27(2.1%) with type IIIB and 18 (1.4%) with type IV. After testing the validity of the classification, different treatment methods were utilized according to the classification, including percutaneous vertebroplasty (PVP) for Type I, PVP after postural reduction for Type II, percutaneous kyphoplasty (PKP) for Type IIIA, posterior reduction and decompression, bone graft fusion and bone cement-augmented screw fixation for Type IIIB, and posterior reduction, bone graft fusion and bone cement-augmented screw fixation for Type IV. The visual analog score (VAS), Oswestry disability index (ODI), Frankel grade of spinal cord injury, local Cobb Angle, and vertebral body angle (vertebral body angle) were recorded in all patients and in each type of patients before surgery, at 1 month after surgery and at the last follow-up. The neurological function recovery and complications were also recorded.Results:The patients were followed up for 24-43 months [(29.9±5.1)months]. A total of 3 000 assessments in two rounds were conducted by three observers. The overall κ value of inter-observer credibility was 0.83, and the overall κ value of intra-observer credibility was 0.88. The VAS and ODI of all patients were (5.8±0.7)points and 72.5±6.6 before surgery, (1.8±0.6)points and 25.0±6.3 at 1 month after surgery, and (1.5±0.6)points and 19.5±6.2 at the last follow-up, respectively (all P<0.05). The Cobb angle and vertebral body angle of all patients were (13.0±9.1)° and (8.0±4.6)° before surgery, (7.9±5.2)° and (4.6±2.9)° at 1 month after surgery, and (9.1±6.0)° and (5.8±3.0)° at the last follow-up, respectively (all P<0.05). At the last follow-up, VAS, ODI, Cobb Angle and VBA of each type of patients were significantly improved compared with those before surgery (all P<0.05). The spinal cord compression symptoms were found 1 patient with type IV and 5 patients with type IIIB preoperatively. At the last follow-up, neurological function improved from grade C to grade E in 1 patient and from grade D to grade E in 5 patients ( P<0.05). The lower limb radiation pain or numbness in 3 patients with type IV and 22 patients with type III preoperatively were fully recovered after surgical treatment at the last follow-up except for three patients. Conclusions:The ASOTLF classification is established and has high consistency and reliability. The classification-oriented treatment strategy has achieved a relatively satisfactory effect, indicating that the classification has a certain guiding significance for treatment of OTLF.

Objective:To explore the risk factors of residual back pain (RBP) in patients undergone PVP within 1 month and further analyze the correlation.Methods:Between March 2013 and January 2015, 1 316 patients with OVCF were treated by PVP. RBP after PVP was defined as a visual analogue scale (VAS) score of > 4 both 1 week and 1 month post-operatively. According to the pain relief, the patients were divided into two groups, the satisfied group and the unsatisfied group. All patients were scheduled for follow-up at1 week, 1 month, 3 months, and 1 year post-operatively, during which radiography and magnetic resonance imaging (T1-weighted, T2-weighted, and short time inversion recovery (STIR) sequences) were recommended to detect the existence of secondary OVCF. VAS scores and Oswestry disability index (ODI) were recorded. Demographic data, surgical information, anesthesia method, number of OVCF, injection amount of cement of single vertebral bone, imaging data and other comorbidity informations of patients in the two groups were analyzed by Logistic regression for the factors related to RBP after PVP.Results:Among 1 316 patients, 60 cases complained RBP, and the prevalence was 4.6%. VAS score and ODI of the two groups were significantly different at 1 week, 1 month and 3 months after surgery, suggesting there was a certain degree of residual pain in the lower back of patients in the unsatisfied group, which was more severe than that in the satisfied group. However, the above differences disappeared in the follow-up of 12 months after surgery.Univariate analysesshowed that preoperative bone mineral density (BMD), number of fracture, cement distribution and volume injected per level and lumbodorsal fascia contusion were associated with RBP after PVP ( P< 0.01, retrospectively). Multivariate analysis revealed that the absolute value of pre-operative BMD(odds ratio ( OR)=3.577, P=0.029), combined withlumbodorsal fascia contusion ( OR=3.805, P=0.002), number of fracture ( OR=3.440, P<0.001), satisfactory cement distribution ( OR=3.009, P=0.013) and combined with depression ( OR=3.426, P=0.028) were positively correlated with RBP after PVP, and these were risk factors. The injection amount of cement of single vertebral bone ( OR=0.079, P<0.001) was negatively correlated with RBP after PVP, which was a protective factor. Conclusion:Pre-operative low BMD, lumbodorsal fascial injury, multiple segment OVCF, insufficient cement injected volume, unsatisfactory cement distribution and depression were risk factors associated with RBP after PVP in patients with OVCF.

Objective:To investigate the physicochemical and biological properties of different magnesium modified calcium phosphate bone cements.Methods:The different magnesium modified calcium phosphate bone cements were divided into magnesium citrate, magnesium lactate, magnesium malate, magnesium phosphate and magnesium glycinate groups, each of which was added with different magnesium agents in the proportion of 0%, 1%, 3% and 5% of the total weight of calcium phosphate bone cements. The initial and final setting time, injectability, anti-collapse performance and compressive strength of different magnesium modified calcium phosphate bone cements were tested. Furthermore, the screened bone cement extracts were used to culture with third generation osteoblasts. Bioactivity assays were performed using the Cell Proliferation and Toxicity Assay Kit (CCK-8). Alkaline phosphatase (ALP) staining and Alizarin Red S (ARS) staining were performed on osteoblasts to observe the osteogenic activity of magnesium malate modified calcium phosphate bone cements.Results:The addition of different proportions of different magnesium agents led to the shortening of the initial and final setting time of modified calcium phosphate bone cements. Moreover, the final setting time of 5% magnesium malate modified calcium phosphate bone cements was the shortest (<40 minutes), which was significantly shorter compared with other magnesium agents in the same proportion (all P<0.05). With the addition of different magnesium agents in different proportions, the injectability of bone cements was gradually increased, and the injectability of 5% magnesium malate calcium phosphate bone cements reached the highest for (87.3±1.9)%, which was significantly increased compared with other magnesium agents in the same proportion (all P<0.05). The anti-collapse performance of bone cements was decreased with the addition of different magnesium agents in different proportions. Magnesium citrate, magnesium phosphate and magnesium glycinate modified calcium phosphate bone cements could not resist the flushing of deionized water. In particular, magnesium malate modified calcium phosphate bone cements had the best anti-collapse performance, with the maximum weight loss rate for only (9.8±2.3)% after 30 minutes of deionized water flushing, which was better than the rest of the groups (all P<0.05). The compressive strength of magnesium lactate and magnesium phosphate modified calcium phosphate bone cements showed a decrease compared with original calcium phosphate bone cements, while the compressive strength of magnesium citrate and magnesium malate modified calcium phosphate bone cements was significantly increased compared with original calcium phosphate bone cements, of which 3% magnesium malate modified calcium phosphate bone cements had the greatest compressive strength of (6.2±0.2)MPa, significantly higher than the rest of the groups (all P<0.05). The sieve test yielded magnesium malate modified calcium phosphate bone cement, which had a weight loss of (27.0±0.9)% at 35 days in vitro. The release of magnesium ions was increased with increasing magnesium malate dose in the in vitro environment of magnesium malate modified calcium phosphate bone cements in different ratios. A stable magnesium ion release was achieved within 35 days.Also, the pro-proliferative and osteogenic effects of modified calcium phosphate bone cements on osteoblasts were more obvious with increase of magnesium malate dose. For 5% magnesium malate modified calcium phosphate bone cements, the cell number, ALP staining area ratio and calcium nodule area ratio were significantly increased compared with the groups in the proportion of 0% and 1% magnesium malate (all P<0.05). Conclusions:Among magnesium citrate, magnesium lactate, magnesium malate, magnesium phosphate and magnesium glycinate modified calcium phosphate bone cements, magnesium malate modified calcium phosphate bone cements have relatively suitable setting time, excellent anti-collapse performance and mechanical strength. Meanwhile, 5% magnesium malate modified calcium phosphate bone cements have better biological activity among different ratios of magnesium malate modified calcium phosphate bone cements, suggesting a potential value for clinical application.

Objective: To analyze the differentially expressed microRNA (miRNA) and their target genes in peripheral blood and bone tissue of postmenopausal osteoporosis (PMOP), and provide basis for the study of pathogenesis as well as biomarkers identification of PMOP. Methods: Two miRNA datasets of PMOP from the public platform NCBI-GEO DataSets were obtained, including GSE64433 (the miRNA expression profile of peripheral blood samples, including 23 PMOP patients and 25 controls) and GSE74209 (the miRNA expression profile of the femoral neck bone tissue sample, including six PMOP patients and six controls). R/Bioconductor was performed for data analysis and differentially expressed miRNA screening, and miRNAs with fold change>2 & P<0.05 between osteoporosis and controls were selected as differentially expressed miRNA. The miRNA target gene prediction was performed by combining TargetScan, miRDB and miRTarBase databases. The miRNA-target gene regulatory network was constructed and analyzed by Cytoscape. Results: There were 224 differentially expressed miRNAs (75 up-regulated miRNAs and 149 down-regulated miRNAs) in the peripheral blood samples of PMOP group (GSE64433 dataset) and 132 differentially expressed miRNAs (58 up-regulated miRNAs and 74 down-regulated miRNAs) in the femoral neck bone tissue of PMOP group (GSE74209 dataset). We combined the results from the two datasets and obtained 8 miRNAs down-regulated in both datasets, and the 8 miRNAs regulated a total of 327 target genes, and 10 of these target genes were co-regulated by two miRNAs. Conclusions The core miRNAs and the target genes regulated by multiple miRNAs in the regulatory network may play important roles in the pathogenesis of PMOP and have potential application values as molecular biomarkers of disease. These findings are meaningful for the studies of PMOP pathogenesis, biomarkers screening and prevention of osteoporotic fractures.

Objective:To analyze the incidence and epidemiological characteristics of traumatic spinal cord injury in China in 2018.Methods:Multi-stage stratified cluster sampling was used to randomly select hospitals capable of treating patients with spinal cord injury from 3 regions，9 provinces and 27 cities in China to retrospectively investigate eligible patients with traumatic spinal cord injury admitted in 2018. National and regional incidence rates were calculated. The data of cause of injury，injury level，severity of injury，segment and type of fracture，complications，death and other data were collected by medical record questionnaire，and analyzed according to geographical region，age and gender.Results:Medical records of 4，134 patients were included in this study，with a male-to-female ratio of 2.99∶1. The incidence of traumatic spinal cord injury in China in 2018 was 50.484 / 1 million （95% CI 50.122-50.846）. The highest incidence in the Eastern region was 53.791 / 1 million （95% CI 53.217-54.365）. In the whole country，the main causes of injury were high falls （29.58%），as well as in the Western region （40.68%），while the main causes of injury in the Eastern and Central regions were traffic injuries （31.22%，30.10%）. The main injury level was cervical spinal cord in the whole country （64.49%），and the proportion of cervical spinal cord injury in the Central region was the highest （74.68%），and the proportion of lumbosacral spinal cord injury in the Western region was the highest （32.30%）. The highest proportion of degree of injury was incomplete quadriplegia （55.20%），and the distribution pattern was the same in each region. A total of 65.87% of the patients were complicated with fracture or dislocation，77.95% in the Western region and only 54.77% in the Central region. In the whole country，the head was the main combined injury （37.87%），as well as in the Eastern and Central regions，while the proportion of chest combined injury in the Western region was the highest （38.57%）. A total of 32.90% of the patients were complicated with respiratory complications. There were 23 patients （0.56%） died in hospital，of which 17（73.91%） died of respiratory dysfunction. Conclusions:The Eastern region of China has a high incidence of traumatic spinal cord injury. Other epidemiological features include high fall as the main cause of injury cervical spinal cord injury as the main injury level，incomplete quadriplegia as the main degree of injury，head as the main combined injury，and respiratory complications as the main complication.