Effect of surgical factors on the augmentation of cement-injectable cannulated pedicle screw fixation by a novel calcium phosphate-based nanocomposite / 医学前沿

Bone cement-augmented pedicle screw system demonstrates great efficacy in spinal disease treatments. However, the intrinsic drawbacks associated with clinically used polymethylmethacrylate (PMMA) cement demands for new bone cement formulations. On the basis of our previous studies, a novel injectable and biodegradable calcium phosphate-based nanocomposite (CPN) for the augmentation of pedicle screw fixation was systematically evaluated for its surgical feasibility and biomechanical performance by simulated and animal osteoporotic bone models, and the results were compared with those of clinical PMMA cement. ASTM-standard solid foam and open-cell foam models and decalcified sheep vertebra models were employed to evaluate the augmentation effects of CPN on bone tissue and on the cement-injected cannulated pedicle screws (CICPs) placed in osteoporotic bone. Surgical factors in CICPs application, such as injection force, tapping technique, screw diameter, and pedicle screw loosening scenarios, were studied in comparison with those in PMMA. When directly injected to the solid foam model, CPN revealed an identical augmentation effect to that of PMMA, as shown by the similar compressive strengths (0.73 ± 0.04 MPa for CPN group vs. 0.79 ± 0.02 MPa for PMMA group). The average injection force of CPN at approximately 40-50 N was higher than that of PMMA at approximately 20 N. Although both values are acceptable to surgeons, CPN revealed a more consistent injection force pattern than did PMMA. The dispersing and anti-pullout ability of CPN were not affected by the surgical factors of tapping technique and screw diameter. The axial pullout strength of CPN evaluated by the decalcified sheep vertebra model revealed a similar augmentation level as that of PMMA (1351.6 ± 324.2 N for CPN vs. 1459.7 ± 304.4 N for PMMA). The promising results of CPN clearly suggest its potential for replacing PMMA in CICPs augmentation application and the benefits of further study and development for clinical uses.

Changes in blood coagulation in middle-aged and elderly patients with fresh vertebral compression fractures / 中华创伤骨科杂志

Objective@#To explore the short-term effects of fresh vertebral compression fracture on blood coagulation in middle-aged and elderly osteoporotic patients.@*Methods@#A retrospective analysis was conducted of the 140 middle-aged and elderly patients (70 ones with fresh vertebral compression fracture and 70 ones with degenerative spinal disease) who had been treated at Department of Orthopaedics, The First Affiliated Hospital to Peking University between January 2016 and December 2018. Collected were their baseline parameters including age, gender and American Society of Anesthesiologists (ASA) scores, preoperative blood parameters including coagulation indicators [D-Dimer, fibrinogen degradation product (FDP), prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (FIB), international normalized ratio (INR) and thrombin time (TT)] and platelets indicators, and fracture parameters including number of fractured vertebrae and duration of fracture. The 2 patients groups were divided into 5 age groups: 4 age groups for each 10 between 50 and 90 years and one age group for >90 years. The values of D-Dimer and FDP were compared between the 2 patient groups in each corresponding age group. The proportions of patients with D-Dimer negative and correlations between coagulation parameters and platelets before and after age adjustment were statistically analyzed.@*Results@#There were no statistically significant differences in the baseline parameters between the 2 patient groups(P>0.05). The mean onset time for the fracture group was 6.7 days. The values of D-Dimer, FDP, PT, INR, TT and FIB in the fracture group were significantly higher than those in the degenerative disease group(P<0.001). After the D-Dimer threshold adjusted by age, 75.71%(53/70) of the patients in the fracture group were negative while 98.57%(69/70) of those in the degenerative disease group were negative. Meanwhile, the values of D-Dimer and FDP showed a significant correlation (P<0.001) with a Pearson correlation coefficient of 0.932. Compared with the degenerative disease group, the values of D-Dimer and FDP in the fracture group increased significantly in the age groups from 61 to 90 years(P< 0.001).@*Conclusions@#Fresh vertebral compression fractures may have a significant effect on the blood coagulation in osteoporotic patients. It is therefore presumed that the middle-aged and elderly patients with fresh vertebral compression fracture may face a higher risk of deep vein thrombosis than those with degenerative spinal disease.

Changes in blood coagulation in middle-aged and elderly patients with fresh vertebral compression fractures / 中华创伤骨科杂志

Objective To explore the short-term effects of fresh vertebral compression fracture on blood coagulation in middle-aged and elderly osteoporotic patients.Methods A retrospective analysis was conducted of the 140 middle-aged and elderly patients (70 ones with fresh vertebral compression fracture and 70 ones with degenerative spinal disease) who had been treated at Department of Orthopaedics,The First Affiliated Hospital to Peking University between January 2016 and December 2018.Collected were their baseline parameters including age,gender and American Society of Anesthesiologists (ASA) scores,preoperative blood parameters including coagulation indicators [D-Dimer,fibrinogen degradation product (FDP),prothrombin time (PT),activated partial thromboplastin time (APTT),fibrinogen (FIB),international normalized ratio (INR) and thrombin time (TT)] and platelets indicators,and fracture parameters including number of fractured vertebrae and duration of fracture.The 2 patients groups were divided into 5 age groups:4 age groups for each 10 between 50 and 90 years and one age group for ＞ 90 years.The values of D-Dimer and FDP were compared between the 2 patient groups in each corresponding age group.The proportions of patients with D-Dimer negative and correlations between coagulation parameters and platelets before and after age adjustment were statistically analyzed.Results There were no statistically significant differences in the baseline parameters between the 2 patient groups(P ＞ 0.05).The mean onset time for the fracture group was 6.7 days.The values of D-Dimer,FDP,PT,INR,TT and FIB in the fracture group were significantly higher than those in the degenerative disease group(P ＜0.001).After the D-Dimer threshold adjusted by age,75.71％ (53/70) of the patients in the fracture group were negative while 98.57％ (69/70) of those in the degenerative disease group were negative.Meanwhile,the values of D-Dimer and FDP showed a significant correlation (P ＜ 0.001) with a Pearson correlation coefficient of 0.932.Compared with the degenerative disease group,the values of D-Dimer and FIDP in the fracture group increased significantly in the age groups from 61 to 90 years(P ＜0.001).Conclusions Fresh vertebral compression fractures may have a significant effect on the blood coagulation in osteoporotic patients.It is therefore presumed that the middle-aged and elderly patients with fresh vertebral compression fracture may face a higher risk of deep vein thrombosis than those with degenerative spinal disease.

Polymethylmethacrylate augmentation of bone cement injectable cannulated pedicle screws was used to treat degenerative lumbar scoliosis with osteoporosis / 北京大学学报(医学版)

Objective:To describe the application of polymethylmethacrylate (PMMA) augmentation of cement-injectable cannulated pedicle screws for the treatment of degenerative lumbar scoliosis with osteoporosis.Methods: Retrospective cohort study was used to compare cement injectable cannulated pedicle screws (CICPs) group with PMMA augmentation and control group with traditional method in the correction surgery for Lenke-silva level Ⅲ and level Ⅳ degenerative scoliosis cases with osteoporosis.Both groups were followed up for 1 year.The clinical results were assessed by visual analog scale (VAS) of pain on lumbar and lower limbers,Oswestry disability index (ODI) score and EuroQol-5 dimensions (EQ-5D) score.The coronal major curve Cobb angel in coronal plane and thoracic kyphosis Cobb angle,lumbar lordosis Cobb angle and sagittal vertical axis (SVA) in sagittal plane were tested in whole long spine X ray.The fusion rates were evaluated by lumbar X ray and dynamic X ray.Results: In this study 34 cases were enrolled,15 cases in CICPs group and 19 cases in control group.The general characteristics including age,gender,weight,height,BMI and BMD were without statistical difference between the two groups.There were (5.7±2.2)PMMA augmentation screws in CICPs group.The operation time,blood loss and blood transfusion were higher in CICPs group than in control group,but without statistical difference.Lumbar VAS,lower limbers VAS,ODI score and EQ-5D were all better in 1 month post-operation,6 months postoperation and 1 year postoperation than in preoperation in both groups.lumbar VAS scores of CICPs group in 6 months postoperation(CICPs group 3.1±1.3 vs.control group 4.4±1.4,P<0.01) together with lumbar VAS scores (CICPs group 3.3±1.0 vs.control group 5.2±1.4,P<0.01),ODI scores (CICPs group 22.7±17.2 vs.control group 31.4±18.5,P<0.01) and EQ-5D in 1 year postoperation (CICPs group 2.9±2.0 vs.control group 3.5±2.5,P<0.01)were lower than those of control group.The coronal major curve Cobb angels were all lower in 1 month postoperation,6 months postoperation and 1 year postoperation than in preoperation in both groups;thoracic kyphosis Cobb angle and lumbar lordosis Cobb angle were all higher in 1 month postoperation,6 months postoperation and 1 year postoperation than in preoperation in both groups.The coronal major curve Cobb angel was lower in CICPs group than that in control group in 1 year postoperation (CICPs group 17.6°±6.9° vs.control group 21.2°±7.2°,P<0.01)and thoracic kyphosis Cobb angle was higher in CICPs group than that in control group in 6 months postoperation (CICPs group-33.5°±8.8 °vs.control group-28.9°±8.3°,P<0.01)and 1 year postoperation(CICPs group-33.0°±8.1° vs.control group-26.3°±7.4°,P<0.01) together with lumbar lordosis Cobb angle were higher in CICPs group than that in control group in 1 year postoperation(CICPs group 26.4°±8.1° vs.control group 22.1°±7.3°,P<0.01).Conclusion: Polymethylmethacrylate augmentation of bone cement-injectable cannulated pedicle screws for the treatment of degenerative lumbar scoliosis with osteoporosis was effective and safe,the short-term clinical result was good.

Efficacy of transforaminal endoscopic nerve root decompression in the treatment of degenerative lumbar spinal stenosis / 北京大学学报(医学版)

Objective:To evaluate the feasibility of transforaminal endoscopic nerve root decompression for degenerative lumbar spinal stenosis (DLSS).Methods: From July 2011 to April 2016,96 cases of single segment DLSS were involved.All the patients had unilateral lower extremity neurological symptoms,signs,neurogenic intermittent claudication of less than 500 m.Imaging examinations (CT or MRI) or diagnostic nerve root block confirmed single segment degeneration.The mean age was (71.6±5.4) years,male: 55 cases,female: 41 cases.Their intraoperative blood loss,operation time,complications,ambulation time and discharge time were recorded.Leg pain VAS,ODI were used to evaluate the pain and lumbar function of the patients.The clinical efficacy was evaluated by Nakai evaluation.Results: All the patients were performed endoscopic decompression of the lateral recess and nerve root by removing the ventral part of the superior facet joint,the ligamentum flavum and the intervertebral disc.The decompression range was from the inferior edge of the upper pedicle to the superior edge of the lower pedicle.The nerve root was detected to have no compression and the pulse of nerve root returned to normal.The patient got ambulant on the operation day and discharged if he had no discomfort symptom.In the study,68 cases got follow up.The mean follow-up time was 12.1 months (6-63 months).The VAS at dif-ferent follow-up time points was improved relative to the baseline,and the difference was statistically significant (F=491.60,P<0.001).The ODI at different follow-up time points was improved relative to the baseline,and the difference was statistically significant (F=189.91,P<0.001).The excellent and good rates of Nakai evaluation were 79.4％ (excellent in 42 cases,good in 12 cases,fair in 10 cases and poor in 4 cases).The mean intraoperative blood loss was (49.29±11.86) mL.The mean operation time was (92.46±21.34) min.The mean ambulation time was 1.8 h.The mean discharge time was 2.3 days.Postoperative epidural hematoma was found in 1 case.Foot drop was found in 1 case.Second stage open surgery was performed in 6 cases.Conclusion: We can apply transforaminal endoscopic decompression for the patients of lumbar spinal stenosis who have unilateral nerve root irritation.Patients with transforaminal endoscopic decompression can get less surgical trauma,quick recovery and obtain good short-term outcome.

Research advances of three-dimension printing technology in vertebrae and intervertebral disc tissue engineering / 浙江大学学报·医学版

Three-dimensional (3D) printing technology is characterized by "inside-out" stack manufacturing. Compared with conventional technologies, 3D printing has the advantage of personalization and precision. Therefore, the shape and internal structure of the scaffolds made by 3D printing technology are highly biomimetic. Besides, 3D bioprinting can precisely deposit the biomaterials, seeding cells and cytokines at the same time, which is a breakthrough in printing technique and material science. With the development of 3D printing, it will make great contributions to the reconstruction of vertebrae and intervertebral disc in the future.

Excellence of differential velocity adherent procedure in primary culture of nucleus pulposus cells of intervertebral disc / 中国组织工程研究

BACKGROUND:As the main function cel of intervertebral disc, nucleus pulposus cel s are the focus of studying the degenerative mechanism;thereby, it is crucial to maintaining the physiological function of nucleus pulposus cel s in vitro and the stability of the cel phenotype. OBJECTIVE:To study the excel ence of differential velocity adherent procedure in primary culture of nucleus pulposus cel s of rat intervertebral disc through comparison. METHODS:Twenty male Wistar rats aged 4 weeks were enrol ed, and then nucleus pulposus cel s of intervertebral disc were isolated and cultured in vitro;cel passage culture was performed in different groups when the primary cel s were merged to 90%. Differential velocity adherent group cel s adhered for 30 minutes, and non-adherent cel s were aspirated and transferred to new culture dish after readjusting the concentration;the controls received no intervention. Passages 1 and 2 cel s in the differential velocity adherent group were isolated and purified by the same procedure. The morphology of three generations of cel s in the two groups was compared, the purity of the identification was detected by immunohistochemistry, the cel viability was detected by cel counting kit-8 and the cel growth curve was drawn. RESULTS AND CONCLUSION:Inverted phase contrast microscope and hematoxylin-eosin staining revealed that the cel homogeneity of the differential velocity adherent group was significantly higher than that of the control group, and there were more kinds of fibroblast-like cel s in nucleus pulposus cel s in the control group. Identification and purity analysis of col agen type II showed that the cytoplasm of two groups were both stained brown, indicating that they were the nucleus pulposus chrondrocytes. The positive rate of differential velocity adherent group was significantly higher than that of the control group (P<0.05). The cel growth curve of cel counting kit-8 showed cel s in the two groups al passed by the latency phase within 2 days, then to the logarithmic phase of 3 days, and entered the lag phase, while the growth rate of the control group was more rapid during the latency and the early logarithmic phases. These findings suggest that differential velocity adherence method is a practical and effective procedure for the isolation and purification of primary cultured rat nucleus pulposus cel s. Through the primary culture, twice differential velocity adherence procedure, the passage 3 rat nucleus pulposus cel s are metabolic exuberant, consistent with the phenotype, the cel purity is higher, and the logarithmic growth phase can be used as the optimal time for studying the mechanism of intervertebral disc cel s.

Clinical research of percutaneous vertebroplasty or percutaneous kyphoplasty for treating osteoporotic vertebral compression fractures induced by glucocorticosteroid / 北京大学学报(医学版)

Objective:To investigate the clinical characteristics of vertebral compression fracture ( VCF) in glucocorticosteroid-induced osteoporosis ( GIOP) and risk of vertebral refracture after percuta-neous vertebroplasty ( PVP) or percutaneous kyphoplasty ( PKP) .Methods:In the study, 570 cases who received PVP or PKP as treatments of VCF from January 2010 to December 2013 were retrospective re-viewed, of which 42 were GIOP and 21 were followed up as GIOP group, and the other 528 were primary osteoporosis and 391 were followed up, of which 84 were selected as Control group based on age and gen-der.The fracture location, ratio of single segment fracture and multiple segments fracture in the two groups were compared.In the final follow up, the reoperation rates for vertebral refractures by the Kap-lan-Meier method in the two groups were compared.Results:The follow up periods were (24.0 ±13.1) months in GIOP group and (25.8 ±14.4) months in control group(P>0.05).In GIOP group, there were 11 cases with one-segment fracture, 2 with two-segments fracture, 3 with three-segments fracture, 2 with four-segments fracture, 2 with five-segments fracture and 1 with eight-segments fracture.In Control group, there were 67 cases with one-segment fracture, 12 with two-segments fracture, 3 with three-seg-ment fracture, and 2 with four-segments fracture.The ratio of single segment fracture in GIOP group was significantly lower than that in Control group(52.4% vs.79.8%,P=0.01).There were 50 fracture segments in GIOP group and 109 fracture segments in Control group.The ratios of fracture segments loca-ted in thoracic segments(T1-T10), thoracolumbar segments(T11-L1)and lumbar segments(L2-L5) were 18%, 46%and 36% in GIOP group and 11.9%, 58.7% and 29.4% in Control group ( P >0.05).The refracture rate in GIOP group was higher than that in control group (23.8%vs.6.0%).The survival rate was lower in GIOP group than that in control group ( Pthoracic segments>lumbar segments).The risk of multiple segments VCF was higher in GIOP than in primary osteoporosis. The risk of vertebral refractures after PVP or PKP was higher in GIOP than in primary osteoporosis.

Effect of polylactic acid-polyglycolic acid copolymer/collagen type Ⅰ microspheres combined with BMSCs on bone defects in osteoporotic rats / 中华骨科杂志

Objective To evaluate the bone repair capacity ofpolylactic acid-polyglycolic acid copolymer (PLGA)/collagen type Ⅰ (CoI) microspheres combined with BMSCs after being injected in intertrochanteric bone defect of osteoporotic female rats.Methods Prepared PLGA microspheres.The microspheres were coated with Col.BMSCs of the third passage were cultured with PLGA/CoI microspheres.Forty 3-month-old female SD rats were ovariectomized to establish osteoporotic animal models.The osteoporotic rats were randomly divided into 5 groups,including SHAM group,PBS group,Cell group,MS group and Cell+ MS group.There were 8 rats in each group.Different material was injected into the intertrochanteric bone defect site which was made with electric drill.Four rats of each group were sacrificed at 1 month and 3 months post-operation.The fenora were taken to measure the intertrochanteric bone mineral density (BMD) with DEXA and evaluate trabecular stucture with Micro CT.Results After 7 days of coculture,BMSCs seeded on PLGA/CoI microspheres had nice adherance and proliferation.There was no difference of BMC and BMD among all groups at 1 month post-operation.Tb.Th of Cell+MS group was higher than that of PBS group and MS group at 1 month post-operation.％Tb.Ar of Cell+MS group was higher than that of Cell group and MS group at 1 month post-operation.Tb.Sp of Cell+MS group had a tendence to decrease compared with other groups but there was no statistical difference at 1 month post-operation.After 3 months of operation,the BMC of Cell+MS group had a tendence to increase compared with that of PBS group and MS group but showed no statistical difference.BMD and Tb.Th of Cell+MS group was higher than those of other groups.％Tb.Ar of Cell+MS group was higher than that of SHAM group and PBS group.Tb.Sp of Cell+MS group had a tendence to reduce compared with other groups but showed no statistical difference.Conclusion The bone defect of osteoporotic site can be repaired 1 month after the injection of the PLGA/CoI microspheres combined with BMSCs.The trabecular reconstruction and bone quality of osteoporotic site can be improved 3 months after the injection.

Relationship between paravertebral vascular leakage and pulmonary cement embolism during percutaneous vertebroplasty / 中国组织工程研究

BACKGROUND:Percutaneous injection of bone cement into the vertebral body can enhance the vertebral strength and vertebral stability, and obtain pain relief. But the bone cement may leakage into the paravertebral vessels during injection, and may back to the right ventricle and flow into the pulmonary artery through vena cave and thus causing pulmonary embolism. OBJECTIVE:To evaluate the relationship between cement paravertebral vascular leakage and pulmonary cement embolism during percutaneous vertebroplasty. METHODS:Total y 134 cases of osteoporotic compression fractures treated with vertebroplasty were retrospectively analyzed. Among them, 23 cases of cement paravertebral vascular leakage were considered as the experimental group, and the 43 cases without cement paravertebral vascular leakage and had the complete imaging data were considered as the control group. The spine and chest X-ray films were taken before and after vertebroplasty to detect whether there were cement paravertebral vascular leakage and pulmonary cement embolism in the patients of two groups. RESULTS AND CONCLUSION:Among the 134 patients, 23 patients had cement paravertebral vascular leakage, and accounted for 17.2%. Among the 23 patients with cement paravertebral vascular leakage, three cases had pulmonary cement embolism without chest symptoms, and accounted for 13%. No pulmonary cement embolism occurred in the 43 patients without paravertebral vascular leakage of the control group, and there was no significant difference between two groups (P=0.039). Although the patients with cement pulmonary embolism remained asymptomatic, pulmonary cement embolism remained possible if cement paravertebral vascular leakage was detected during vertebroplasty.

Influencing factors for radial shortening after surgical operation for intra-articular fractures of the distal radius / 中华创伤杂志

ObjectiveTo analyze the influencing factors and clinical results of radial shortening after operation of intra-articular fractures. MethodsA total of 54 patients with intra-articular fractures of the distal radius treated surgically from January 2003 to January 2008 were followed up and divided into radial shortening group ( ＞ 4 mm) and control group ( ＜ 4 mm) by whether radial shortening was more than 4 mm. Fracture types, comminution and defection degree, age, surgical approach and internal fixation method, whether bone implant in operation, post-operative volar tilting angle and ulnar inclination angle, and wrist function score were investigated and compared between the two groups. ResultsThe incidence of radial shortening in post-operation of intra-articular fractures of the distal radius was 30％.Age and whether bone implant in operation were significantly different between the two groups. Type C fractures were more liable to radial shortening than type B fractures. Operation approach and internal fixation method have no significant influence on the radial shortening. Volar tilting angle and ulnar inclination angle were not significantly different between the two groups and the excellent and good rate of function score was lower in the radial shortening group. ConclusionThere is a high incidence of radial shortening after operation for the intra-articular fractures of the distal radius, which affects the clinical results of operation. Therefore, we should pay more attention to the influencing factors and take corresponding precaution methods during operation.

Bioresorbable cage for interbody fusion Progress in research and clinical application / 中国组织工程研究

BACKGROUND: The use of interbody cages is rapidly increasing in filed of spinal fusion surgery. The inherent limitations of conventional cages such as cage migration or failure, radiopacity, fusion stress shielding, late-onset inflammation and osteolysis give some impetus for the development of bioresorbable cages. Compared with conventional cages, they show better rigidity and elasticity coefficient, with less interference on the imaging evaluation. OBJECTIVE: To introduce the materials classification and property, animal studies, clinical application, current drawbacks and future directions of bioresorbable fusion cages, and provide objective evidences for the research and clinical application of the cages.RETRIEVAL STRATEGY: The relevant articles published between December 1990 and December 2006 were searched for in Pubmed database by the researchers of this article, with the key words "bioresorbable cages, spine, SCI" in English. A total of 550 articles were selected and reviewed preliminarily by the inclusive standards of: research about materials, animal studies and clinical application of bioresorbable cages. Exclusion criteria: repetitive studies.LITERATURE EVALUATION: The main sources of literatures are researches about materials, animal studies and clinical application of bioresorbable cages. Among the 27 selected articles, 1 is review, while others are clinical or elementary experimental studies. DATA SYNTHESIS: ①Materials: Polylactides becomes the most useful and applied base material for bioresorbable spinal interbody cages; characteristics of bioresorbable materials include crystallinity, average molecular weight, molecular weight distribution (polydispersity), and glass transition temperature. There are also several points to consider in the design of bioresorbable cages such as characters related to degradation, functional degradation rate, intensity of inflammatory response and occupation by other tissues following degradation.②Animal studies: Quadruped can be a valuable model for the study of the spine, but it has its limitations; Researches in vitro are focused on these cages of their degradation characters and maintenance of the spinal elasticity; Researches in vivo consisted of the characters of biomechanics, degradation, fusion and foreign body reactions of these cages.③Clinical application: Bioresorbable cages are satisfactory for the clinical application in the TLIF, PLIF of lumbar operation and the ACDF of cervical operation in short term follow up study.④Bioresorbable cages have their drawbacks, which may bring about the development of related techniques.CONCLUSION:The research and application of bioresorbable cages are at the preliminary stage, but the results that we have got are promising for their further research and clinical application.