A Preliminary Study on the Morphological Changes of an NiTi-Shaped Memory Alloy Stent in the Vertebral Body.

OBJECTIVE: At present, the most commonly used filler polymethyl methacrylate (PMMA) has the disadvantages of monomer toxicity, heat and leakage, and cannot be applied in young people. Therefore, finding a minimally invasive and good tissue-compatible alternative material has been a research hotspot in spine surgery in recent years. The aim of this study is to explore whether the memory alloy stent can avoid the complications of bone cement or not. METHODS: Four non-adjacent vertebral bodies of the thoracic and lumbar spine in the 18 10-month-old pigs were selected as the surgical site and were randomly divided into the scaffold group and the bone cement group. The memory alloy scaffold and PMMA (polymethyl methacrylate) bone cement were placed via percutaneous puncture, and intraoperative fluoroscopy and micro-CT were used to observe the changes in the height of scaffolds and bone cement in the vertebral body immediately, 6 weeks, and 12 weeks after operation, the microstructural parameters of the bone trabeculae (bone volume fraction, bone surface volume ratio, bone trabeculae number) were also measured. RESULTS: The memory alloy stent could expand in the vertebral body, and its height gradually increased with time; additionally, the height of the bone cement mass did not change with time (p = 0.00). New bone trabeculae could grow into the scaffold along the gap, and the volume fraction of bone, the volume ratio of bone surface area, and the number of bone trabeculae increased gradually (p = 0.00). However, the volume fraction of bone, the volume ratio of bone surface area, and the number of trabeculae in the cement block decreased gradually (p = 0.00). CONCLUSIONS: Memory alloy scaffolds have dynamic expansion characteristics in vivo, which can effectively avoid the complications of bone cement. Thus, it is beneficial to explore this minimally invasive treatment for vertebral compression fractures.

In vitro cytological comparison of osseointegration properties between biomimetic bone trabecular and regular porous structure / 西安交通大学学报(医学版)

【Objective】 To investigate the effects of biomimetic bone trabecular with the same porosity and pore size and regular porous structure on the adhesion, proliferation, and differentiation of osteoblasts, so as to provide theoretical basis for the improvement of osseointegration performance of titanium alloy implants. 【Methods】 The biomimetic bone trabecular and regular porous structures with the same porosity and pore size were generated by computer-aided software, and then processed into disc-shaped Ti6Al4V scaffolds with a diameter of 10 mm and a height of 3 mm by selective laser melting technology. MC3T3-E1 cells, the precursor cells of mouse osteoblasts in the logarithmic growth phase, were seeded on two kinds of scaffolds and divided into biomimetic bone trabecular group and regular porous structure group. After 3 hours of culture, acridine orange staining and phalloidin /DAPI staining were used to evaluate the number of cell adhesion. After 3 days of culture, the scaffolds were examined by scanning electron microscopy to evaluate the adhesion state of cells. After 1, 3, and 5 days of culture, the scaffolds were taken for CCK8 detection to observe the proliferation of cells. After 7 and 14 days of differentiation, alkaline phosphatase (ALP) activity was detected. After 14 days of differentiation, the expressions of osteogenesis-related genes (ALP, OCN, RUNX2) were detected by RT-PCR. After 30 days of differentiation, the scaffolds were stained with alizarin red and 100 g/L cetylpyridinium chloride was used to dissolve mineralized nodules. Calcium salt deposition was qualitatively and quantitatively detected to evaluate cell differentiation. 【Results】 The results of acridine orange and phalloidin /DAPI staining showed that the biomimetic trabecular Ti6Al4V scaffold adhered to more MC3T3-E1 cells than the regular porous structure, and the cytoskeleton of the former scaffold was more densely distributed. The results of scanning electron microscopy showed that the pseudopodia of MC3T3-E1 cells on the biomimetic bone trabecular Ti6Al4V scaffold were longer and the extension state was better than that of the regular porous structure. CCK8 test showed that the proliferation of MC3T3-E1 cells on the biomimetic trabecular bone titanium alloy scaffold was significantly higher than that on the regular porous structure on the 3rd and 5th day, and the difference gradually increased with the increase of time, with statistical significance (P<0.05). The results of cell differentiation test showed that ALP activity on the bionic trabecular scaffold was higher than that on the regular porous structure (P<0.05). The expressions of osteogenic genes (ALP, OCN, RUNX2) in MC3T3-E1 cells on the biomimetic bone trabecular titanium alloy scaffold were significantly higher than those on the regular porous structure (P<0.05). After 30 days of induction, the amount of calcium salt deposited in the bionic trabecular titanium alloy scaffold was significantly larger than that in the regular porous structure (P<0.05). 【Conclusion】 The biomimetic bone trabecular with a porosity of 65% and an equivalent pore size of 600 μm is more conducive to the adhesion, proliferation and differentiation of mouse osteoblast precursor cells MC3T3-E1 on the titanium alloy scaffold than the regular porous structure with the same porosity and pore size. It is theoretically more conducive to improving the osseointegration performance of titanium alloy implants.

Feasibility of Two-Screw Anterior Fixation for Odontoid Fractures in a Chinese Population:A Morphometric Study Based on Computed Tomography

Background@#To evaluate the feasibility of treating odontoid fractures in the Chinese population with two cortical screws based on computed tomography (CT) scans and describe a new measurement strategy to guide screw insertion in treating these fractures. @*Methods@#A retrospective review of cervical computed tomographic scans of 128 patients (aged 18–76 years; men, 55 [43.0%]) was performed. The minimum external transverse diameter (METD), minimum external anteroposterior diameter (MEAD), maximum screw length (MSL), and screw projection back angle (SPBA) of the odontoid process were measured on coronal and sagittal CT images. @*Results@#The mean values of METD and MEAD were 10.0 ± 1.1 mm and 12.0 ± 1.0 mm, respectively, in men and 9.2 ± 1.0 mm and 11.0 ± 1.0 mm, respectively, in women. Both measurements were significantly higher in men (p 9.0 mm that could accommodate two 3.5-mm cortical screws. The mean MSL value and SPBA range were 34.4 ± 2.9 mm and 13.5°–24.2°, respectively, with no statistically significant difference between men and women. @*Conclusions@#The insertion of two 3.5-mm cortical screws was possible for anterior fixation of odontoid fractures in 87 patients (68%) in our study, and there was a statistically significant difference between men and women.

Risk factors for refracture of injured vertebrae after percutaneous vertebral augmentation for acute symptomatic thoracolumbar osteoporotic compression fractures / 中华创伤杂志

Objective:To investigate the risk factors of refracture of the injured vertebrae after percutaneous vertebral augmentation for acute symptomatic thoracolumbar osteoporotic compression fractures (ASTOCFs).Methods:A case-control study was conducted to analyze the clinical data of 2 237 ASTOCFs patients admitted to three hospitals from January 2010 to January 2019. There were 569 males and 1 668 females, with age range of 50-85 years [(66.7±4.8)years]. The patients underwent percutaneous vertebroplasty (PVP) or percutaneous kyphoplasty (PKP). According to the radiographic outcomes, the patients were divided into refracture group ( n=315) and non-refracture group ( n=1 922). Data were recorded for the two groups, including basic demographics (gender, age, height and weight), personal habits (smoking and alcohol consumption), basic diseases (diabetes, hypertension, coronary heart disease and chronic obstructive pulmonary disease), preoperative bone mineral density, fracture segment, number of injured vertebrae, surgical method (PVP or PKP), surgical approach, bone cement viscosity, distance from cement to the upper and lower endplate, cement volume in injured vertebrae, cement leakage, postoperative exercise, and postoperative anti-osteoporosis treatment. The above data were analyzed to identify their correlation with postoperative refracture of the injured vertebrae by univariate analysis. The independent risk factors for postoperative refracture of the injured vertebrae were determined by multivariate Logistic regression analysis. Results:Univariate analysis showed that refracture of injured vertebrae was correlated with gender, age, diabetes, fracture segment, surgical method, distance from cement to the upper and lower endplate, postoperative exercise, and postoperative anti-osteoporosis treatment ( P<0.05 or 0.01), but there was no correlation with height, weight, smoking, alcohol consumption, hypertension, coronary heart disease, chronic obstructive pulmonary disease, preoperative bone mineral density, number of fractured vertebrae, surgical approach, bone cement viscosity, cement volume in injured vertebrae or cement leakage (all P>0.05). Multivariate Logistic regression analysis showed that female ( OR=1.92, 95% CI 1.34-2.64, P<0.01), age ≥80 years ( OR=1.21, 95%CI 1.17-1.25, P<0.01), diabetes ( OR=1.92, 95% CI 0.44-2.55, P<0.01), thoracolumbar fracture ( OR=1.46, 95% CI 1.82-7.51, P<0.05), PKP ( OR=4.56, 95% CI 0.86-1.44, P<0.05), no postoperative exercise ( OR=2.14,95% CI 0.27-0.38, P<0.01), and no postoperative anti-osteoporosis treatment ( OR=2.36,95% CI 0.13-0.47, P<0.05) were positively correlated with refracture of injured vertebrae. Conclusion:Female, age ≥80 years, diabetes, thoracolumbar fracture, PKP, no postoperative exercise, and no postoperative anti-osteoporosis treatment are independent risk factors for refracture of injured vertebrae after percutaneous vertebral augmentation for ASTOCFs.

Comparison of the effect of endoscopic discectomy through interlaminar approach for lumbar disc herniation under local or general anesthesia / 西安交通大学学报(医学版)

【Objective】 To investigate the effect or endoscopic discectomy via interlaminar approach in the treatment of lumbar disc herniation under local or general anesthesia. 【Methods】 We selected 78 patients with lumbar disc herniation （L5-S1） who underwent endoscopic discectomy via interlaminar approach from January 2018 to February 2020. According to the anesthesia method， they were divided into local anesthesia group （40 patients） and general anesthesia group （38 patients）. Baseline data， complications， operation time， length of hospital stay， hospitalization expenses， preoperative and postoperative VAS scores were compared between the two groups to evaluate the difference in clinical outcomes. 【Results】 There was no significant difference between the two groups in gender （23/17 vs. 20/18）， age （38.45±13.59 vs 37.39±13.35） years， preoperative VAS score （7.05±1.32 vs. 6.95±1.47）， or other baseline data （P>0.05）. The operation was completed successfully in both groups， and the operation time （83.57±13.24 vs. 86.28±15.43） minutes did not statistically differ （P>0.05）. No complications such as cerebrospinal fluid leakage， nerve injury， or wound infection occurred. In the local anesthesia group， the VAS pain score at 1d， 1 month and 6 months after surgery was 3.05±1.34， 1.90±0.98 and 1.80±1.09， respectively， which were significantly lower than those before surgery （P<0.001）. The VAS pain scores of the general anesthesia group at the above three time points were 3.24±2.01， 2.03±1.20 and 1.59±1.31， respectively， which were also significantly lower than those before surgery （P<0.001）， but the difference was not statistically significant compared with that of the local anesthesia group at the same time point （P>0.05）. However， compared with the general anesthesia group， the length of hospital stay （2.93±0.92） d and the cost of hospitalization （29 397.97±1 398.09） yuan in the local anesthesia group were decreased by 25.8% and 11.7%， respectively， with statistical significance （P<0.05）. 【Conclusion】 Endoscopic discectomy through interlaminar approach under local or general anesthesia can achieve good clinical outcomes in the treatment of lumbar disc herniation （L5-S1）. Compared with general anesthesia， local anesthesia brings a lower overall cost and a shorter hospital stay.

Clinico-pathological investigations of a distinct variant of focal cortical dysplasia characterized by neuronal loss of layer four / 中华神经科杂志

Objective To investigate the clinical pathologic features of a distinct variant of focal cortical dysplasia (FCD) characterized by neuronal loss of layer four.Methods Between 2005 and 2017,approximately 3 000 surgeries were performed for the treatment of intractable epilepsy at Xuanwu Hospital,Capital Medical University and Yuquan Hospital,Tsinghua University.Retrospective analysis of clinic-pathological data of patients with epilepsy surgery was made and histological manifestations of neuronal loss of cortical layer four were included in this study.Results In this cohort,25 patients (22 males and three females) were identified with early onset pharmaco-resistant epilepsy and regionally circumscribed neuronal loss of cortical layer four in surgical specimens from the occipital lobe.Histologically,except for neuronal loss in cortical layer four in all cases,glial scar lesions were found in some patients.Thus the histology of those cases can be subdivided into two groups:group A (13 cases):neuronal loss of cortical layer four without glial scar lesions;and group B (12 cases):neuronal loss of cortical layer four with glial scar lesions.Due to the prominent horizontal disorganization of cortical layering and lack of any other microscopically visible principle lesion,group A should be classified hitherto as FCD International League Against Epilepsy (ILAE) type Ⅰ b,however,group B with scar lesions and cortical dysplasia around the main leision,should be classified as FCD ILAE type Ⅲd.This retrospective analysis of clinical histories revealed a perinatal distress in 20 patients (80％),suggesting an acquired pathomechanism.Magnetic resonance imaging revealed abnormal signals in the occipital lobe in all patients,and signal changes suggestive of encephalomalacia were found in 18 patients.Surgical treatment achieved favorable seizure control (Engel class Ⅰ and Ⅱ) in 18 patients (75％ among 24 available follow up).Comparion of the two groups with age at epilepsy onset (group A:5.00±2.76,group B:5.01±3.78),the proportion of perinatal distress (group A:11/13,group B:9/12) and the follow-up results (favorable seizure control of the two groups was 9/13,9/11 respectively) showed that there was no statistically significant difference between the two groups.Conculsion Neuronal loss of cortical layer four in the occipital lobe should be classified as a distinct variant of FCD ILAE type Ⅲd.

Effect of total knee arthroplasty after limb position on postoperative hemorrhage / 中国基层医药

Objective To study the effect of total knee arthroplasty after limb position on postoperative hemorrhage,to provide basis for clinical diagnosis and treatment.Methods 270 cases of total knee arthroplasty were selected.The patients were divided into groupⅠ,group Ⅱand group Ⅲ according to the random number table method, 90 cases in each group.Patients of group Ⅰ with limb hip and knee were straight,group Ⅱ hip joint elevation of 45 degrees,70 degrees of knee flexion,group Ⅲ hip joint elevation of 45 degrees,the knee extension.All the patients were intervened for 12h after operation,were placed drainage bag 24 hours.The lead flow,preoperative,postoperative hemoglobin and 5 days after the knee joint activity were compared in the three groups.Results Induced flow after surgery in group Ⅰ was (433.4 ±25.3)mL,which was significantly higher than (402.6 ±19.6)mL and (403.5 ± 21.5)mL in group Ⅱand group Ⅲ,and the differences were statistically significant (t =5.253,5.301,all P 0.05).The hemoglobin levels of the three groups were (92.3 ±4.2)g/L,(114.9 ±6.4)g/L and (113.2 ±7.5)g/L,which were significantly decreased after operation,the differences were statistically significant compared with before operation (t =5.083, 6.034,7.893,all P 0.05).There was no significant difference of range of motion in the three groups after 5 days of operation (P >0.05).Conclusion Hip flexion can effectively reduce bleeding after total knee arthro-plasty,the flexion and extension of knee joint had no significant effect on postoperative hemorrhage.

Effect of improved storage type of autologous blood transfusion combined with shed blooding retransformation technique after OrthoPAT for artificial total knee arthroplasty / 中国基层医药

Objective To investigate the clinical effect of modified storage type of autologous blood transfu-sion combined with shed blooding retransformation technique after OrthoPAT for artificial total knee arthroplasty. Methods 70 patients with total knee replacement were randomly divided into observation group and control group, 35 cases in each group.The observation group was treated with the modified storage autotransfusion combined shed blooding retransformation technique after OrthoPAT,while the control group was given conventional allogeneic blood transfusion.The hemoglobin values and blood coagulation function of the two groups at immediately before anesthesia and surgery,10min before autologous blood transfusion and after reinfusion of 15min,after 6h and 24h of surgery were recorded,and the drainage blood total value,allogeneic blood transfusion measurement issues and transfusion rate after 24h were recorded.Results The hemodynamics of the two groups were stable at each time,there were no difference at urine volume (all P >0.05).The coagulation conditions were normal of the two groups at each time,there were no statistically significant differences between the two groups (all P >0.05).The average volume and homologous blood transfusion rate in the observation group were (126.3 ±6.5)mL,1 /35,which were significantly lower than those in the control group [(476.4 ±10.6)mL,2 /35],the differences were statistically significant (t =10.73,χ2 =6.31,all P <0.05).The incidence rate of postoperative complication of the observation group was 5.7%,which was signifi-cantly lower than 22.9% of the control group,the difference between the two groups was statistically significant (χ2 =4.93,P <0.05).Conclusion The improved storage type of autologous blood transfusion combined with shed bloo-ding retransformation technique after OrthoPAT has exact effect for artificial total knee arthroplasty,the incidence of adverse reactions is low,as well as the low blood transfusion rate.

[Explorations of epileptic network with cortico-cortical evoked potential].

OBJECTIVE: To evaluate the cortico-cortical evoked potential (CCEP) in exploring the network in epileptics. METHODS: Two patients with intractable epilepsy underwent chronic intracranial electrode placement. According to the distribution of icta onset zones and the functional brain mapping, alternating 1 Hz electrical stimuli were delivered to the target electrodes. And CCEPs were recorded by averaging electrocorticograms time-locked to stimuli from subdural electrodes. Then icta onset zones, eloquent areas identified by electrical cortical mapping and CCEP distributions were compared. RESULTS: Typical CCEP responses were observed. The data of one patient was useful for investigating the connectivity associated with various brain networks while another patient was useful for evaluating the cortical excitability. CONCLUSION: The exploration of epileptic network is achieved through cortico-cortical evoked potential by investigating the connectivity associated with various brain networks and cortical excitability.

Applications of memory alloy stent in vertebral fractures.

BACKGROUND: The aim of this study was to evaluate the feasibility of treating vertebral compression fractures using an autonomously developed nitinol memory alloy vertebral stent. MATERIAL AND METHODS: Thoracolumbar vertebral specimens from adult human cadavers were made into models of compression fractures. The models were divided into group A, which received percutaneous kyphoplasty (PKP), balloon dilation, and nitinol memory alloy vertebral stent implantation (PKP + nitinol stent group); group B, which received percutaneous vertebroplasty (PVP) and direct implantation of a nitinol memory alloy vertebral stent (PVP + nitinol stent group); and group C, which received PKP, balloon dilation, and bone cement vertebroplasty (PKP + polymethylmethacrylate (PMMA) group). Vertebral heights were measured before and after the surgery and the water bath incubation to compare the impact of the 3 different surgical approaches on reducing vertebral compression. RESULTS: The 3 surgical groups could all significantly restore the heights of compressed vertebral bodies. The vertebral heights of the PKP + nitinol stent group, PVP + nitinol stent group, and PKP + PMMA group were changed from the preoperative levels of (1.59±0.08) cm, (1.68±0.08) cm, and (1.66±0.11) cm to the postoperative levels of (2.00±0.09) cm, (1.87±0.04) cm, and (1.99±0.09) cm, respectively. After the water bath, the vertebral heights of each group were changed to (2.10±0.07) cm, (1.98±0.09) cm, and (2.00±0.10) cm, respectively. Pairwise comparison of the differences between the preoperative and postoperative vertebral heights showed that group A and group B differed significantly (P=0.000); group B and group C differed significantly (P=0.003); and group A and group C had no significant difference (P=0.172). Pairwise comparison of the differences in the vertebral heights before and after the water bath showed that group A and group C differed significantly (P=0.000); group B and group C differed significantly (P=0.000); and group A and group B had no significant difference (P=0.157). CONCLUSIONS: The nitinol memory alloy stents can effectively support and reduce the compression of vertebral endplates and can be used to treat vertebral compression fractures without neurological symptoms.

The threshold of cortical electrical stimulation for mapping sensory and motor functional areas.

This study aimed to investigate the threshold of cortical electrical stimulation (CES) for functional brain mapping during surgery for the treatment of rolandic epilepsy. A total of 21 patients with rolandic epilepsy who underwent surgical treatment at the Beijing Institute of Functional Neurosurgery between October 2006 and March 2008 were included in this study. Their clinical data were retrospectively collected and analyzed. The thresholds of CES for motor response, sensory response, and after discharge production along with other threshold-related factors were investigated. The thresholds (mean ± standard deviation) for motor response, sensory response, and after discharge production were 3.48 ± 0.87, 3.86 ± 1.31, and 4.84 ± 1.38 mA, respectively. The threshold for after discharge production was significantly higher than those of both the motor and sensory response (both p<0.05). A negative linear correlation was found between the threshold of after discharge production and disease duration. Using the CES parameters at a stimulation frequency of 50 Hz and a pulse width of 0.2 ms, the threshold of sensory and motor responses were similar, and the threshold of after discharge production was higher than that of sensory and motor response.

Current status of percutaneous vertebroplasty and percutaneous kyphoplasty--a review.

Percutaneous vertebroplasty (PV) and kyphoplasty (PK) are the 2vertebral augmentation procedures that have emerged as minimally invasive surgical options to treat painful vertebral compression fractures (VCF) during the last 2 decades. VCF may either be osteoporotic or tumor-associated. Two hundred million women are affected by osteoporosis globally. Vertebral fracture may result in acute pain around the fracture site, loss of vertebral height due to vertebral collapse, spinal instability, and kyphotic deformity. The main goal of the PV and PK procedures is to give immediate pain relief to patients and restore the vertebral height lost due to fracture. In percutaneous vertebroplasty, bone cement is injected through a minimal incision into the fractured site. Kyphoplasty involves insertion of a balloon into the fractured site, followed by inflation-deflation to create a cavity into which the filler material is injected, and the balloon is taken out prior to cement injection. This literature review presents a qualitative overview on the current status of vertebral augmentation procedures,especially PV and PK, and compares the efficacy and safety of these 2 procedures. The review consists of a brief history of the development of these 2 techniques, a discussion on the current research on the bone cement, clinical outcome of the 2 procedures, and it also sheds light on ongoing and future research to maximize the efficacy and safety of vertebral augmentation procedures.