Objective    To investigate the effect of simvastatin and mechanical pretreatment on intimal hyperplasia of venous graft and its mechanism. Methods    Twelve New Zealand rabbits were selected and randomly divided into 4 groups: a blank control group, a simvastatin topical treatment group, a mechanical precondition group and a combined group (n=3 in each group). Ultrasound was used to evaluate the changes of graft wall and blood flow velocity in the graft, and pathological section was used to evaluate the intimal hyperplasia. Human umbilical cord endodermal cells were cultured in vitro. A simvastatin group and a solvent control group were set to detect YAP phosphorylation, downstream target gene expression and cell proliferation. Results    Vascular ultrasound showed that except the simvastatin topical treatment group, the flow velocity in vein grafts in the other three groups significantly increased 21 days after surgery compared with 7 days after surgery (P<0.01). Pathological sections showed that the thickness of new intima in the simvastatin topical treatment group, mechanical precondition group, combined group and blank control group were 45.56±4.11 μm, 201.28±16.71 μm, 143.57±7.82 μm, 249.45±13.33 μm, respectively, and there were statistical differences compared with the blank control group (P<0.05). In vitro results showed that compared with the solvent control group, cell death was observed in high concentration simvastatin (5 mmol/L) group, cell proliferation was inhibited in low concentration simvastatin (2.5 mmol/L) group (P<0.05), the expression of YAP protein in the simvastatin group was unchanged, but the expression of phosphorylated YAP protein significantly increased (P<0.05), and the expression of downstream target gene ccn1 was down-regulated (P<0.001). Conclusion    Intravascular local application of simvastatin and mechanical preconditioning alone or in combination can inhibit intimal hyperplasia of venous graft. High concentration of simvastatin has cytotoxicity, while low concentration of simvastatin has inhibitory effect on cell proliferation. Simvastatin can inhibit the formation of new intima by inhibiting the entry of YAP into the nucleus and reducing the transcription of cell proliferation-related target gene ccn1.

Objective:To compare the therapeutic results between axis pedicle screwing assisted by intraoperative 3-D navigation and freehand axis pedicle screwing in the treatment of Hangman fracture.Methods:A retrospective analysis was performed of the 64 patients with Hangman fracture who had received posterior axis pedicle screwing at Department of Spinal Surgery, The Sixth Hospital of Ningbo from May 2014 to December 2019. According to the placement methods of axis pedicle screws, they were divided into a navigation group ( n=34, subjected to axis pedicle screwing assisted by intraoperative 3-D navigation) and a freehand group ( n=30, subjected to freehand axis pedicle screwing). Pedicle screw placement time, operation time, intraoperative bleeding, fluoroscopy time, hospital stay, total hospitalization cost and complications were recorded and compared between the 2 groups. The accuracy of axis pedicle screw placement was evaluated according to the postoperative cervical CT and screw grading criteria proposed by Park et al. At admission, 3 months postoperation, and the last follow-up, neurological function of the patients was evaluated by modified Japanese Orthopedic Association (mJOA) score, neck pain was evaluated by visual analogue scale (VAS), and C2/3 vertebral body angulation and C2 forward displacement were measured. The clinical efficacy was evaluated by Moon grading at the last follow-up. Results:The navigation group and the freehand group were comparable due to insignificant differences between them in the preoperative general data ( P>0.05). The accuracy of screw placement in the navigation group (98.2%, 54/55) was significantly higher than that in the freehand group (85.2%, 46/54) ( P<0.05). The screw placement time, operation time, fluoroscopy time and total hospitalization cost in the navigation group were significantly more than those in the freehand group ( P<0.05). Vertebral artery injury occurred in 3 cases in the freehand group. Screw loosening, screw breakage or rod breakage occurred in none of the patients after operation. There was no significant difference between the 2 groups in the intraoperative bleeding, hospital stay or follow-up time ( P>0.05). In both groups, the VAS score, mJOA score, C2/3 vertebral body angulation and C2 forward displacement were significantly improved at 3 months postoperation and the last follow-up compared with those at admission ( P<0.05), but there was no significant difference between the 2 groups in the contemporary comparisons ( P>0.05). At the last follow-up, Moon grading in the navigation group was significantly better than that in the freehand group ( P<0.05). Conclusion:In the treatment of Hangman fracture, compared with freehand screw placement, axis pedicle screwing assisted by intraoperative 3-D navigation can improve accuracy and safety of screw placement and reduce postoperative complications, leading to better clinical efficacy.

Objective:To investigate the impact on image quality of a new deep learning image reconstruction (DLIR) algorithm in dynamic CT myocardial perfusion imaging (CTP) and to explore whether the algorithm affects the quantification of myocardial blood flow (MBF) in swine.Methods:Dynamic CTP imaging was performed in five anesthetized domestic swine [body weight (58.6±1.9) kg], at both rest and stress state. The tube voltages were fixed at 100 kV, and the low-dose and high-dose scanning tube currents were set as 150 mA and 300 mA, respectively. The low-dose (LD) scan data were reconstructed with filtered back projection (FBP) and three different DLIR strengths (low, medium, and high). High-dose (HD) scan data were reconstructed with filtered back projection (FBP) only. Subjective (5-point scale) image quality was evaluated, and objective evaluations included image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) was performed. Linear regression was used to test the linear trend between DLIR algorithm strength and image quality. Data sets normality was determined by the Shapiro-Wilk test. Comparisons between groups were performed using Student′s t test for normally distributed data or the Wilcoxon rank-sum test for non-normally distributed data. Results:The mean effective radiation dose was 7.2 and 3.8 mSv for the HD protocol and the LD protocol, respectively, with statistically significant difference found between two protocols ( t=282.50, P<0.001). The image noise of the images obtained at LD protocol gradually decreased and the image SNR and CNR gradually increased with DLIR algorithm strength increased ( F=60.10,35.87,41.41; P for trend were all<0.001). As for DLIR-high strength (LD) and FBP (HD) images, the image noise values were (31.7±3.1) and (38.2±1.2) HU; SNR were 16.6±2.0 and 13.8±0.8; CNR were 14.5±1.7, 11.6±0.9, respectively, with significant differences found between two groups ( t=5.70, 4.15, 5.68; all P<0.05). The subjective scores of DLIR-high strength (LD) and FBP (HD) images were significantly different (4.8±0.4 and 4.2±0.6, Z=2.12, P<0.05). No significant differences were found between the MBF calculated from FBP (LD) and from DLIR-high strength (LD), with the values as (81.3±17.3) ml·100 ml -1·min -1 vs. (79.9±18.3)ml·100 ml -1·min -1 at rest state; and (99.4±24.9)ml·100 ml -1·min -1 vs. (100.7±27.3) ml·100 ml -1·min -1 at stress state ( t=1.10, 0.89; P>0.05). Conclusion:DLIR-high strength can improve image quality of myocardial CTP in swine, and can reduce radiation dose without influencing the MBF calculation.

Objective To evaluate the accuracy in placement of cervical anterior transpedicular screws (ATPS) under the guidance of our modified drilling template.Methods Eight wet cadaveric specimens of adult cervical spine,4 male and 4 female ones,were used for this experiment.Data of CT thin layer scanning of the cervical specimens in DICOM format were imported into software Mimics 17.0.After 3D models of the cervical vertebrae were reconstructed,the optimal trajectory was designed for ATPS placement in the transparent mode of the 3D models.Normal and our modified drilling templates for ATPS placement were designed and manufactured by 3D printing.The 2 kinds of drilling templates were used to assist ATPS placement onto one cervical vertebra,with laterality randomized.Altogether 64 pieces of ATPS were placed,with 32 ones for each drilling template.Postoperative CT scanning was conducted to evaluate the accuracy in ATPS placement.The 2 kinds of ATPS template were compared in terms of the deviations between actual and ideal trajectories in direction (caudal-angle and extroversive-angle) and position (X and Y axes) of the entry point.Results Our modified drilling template led to one screw penetrating the pedicle cortical bone while the normal drilling template led to 4 screws penetrating the pedicle cortical bone,yielding an accuracy rate of 96.9％ and of 87.5％ respectively.The extroversive-angle deviation (0.72°±0.69°),caudal-angle deviation (0.91°±0.70°),X axis shift (0.53 ±0.40 mm) and Y axis shift (0.54 ±0.42 mm) related to the modified template were all significantly smaller than those related to the normal template (1.16° ± 0.70°,1.49°±0.68°,0.88±0.40mm,1.22±0.42mm,respectively) (P ＜0.05).Conclusion Compared with a normal ATPS template,our modified drilling template for ATPS may be advantageous in better fitness,greater stability,increased accuracy in screw placement,and protection of adjacent discs.

Objective To analyze the causes of revision surgery after percutaneous transforaminal endoscopic discectomy (PTED) for lumbar spinal stenosis,and to provide references for indications and operative methods.Methods From January 2015 to October 2017,206,491 and 60 patients of lumbar spinal stenosis were treated with PTED in Tianjin Hospital,Shanxi People's Hospital,Ningbo Sixth Hospital,respectively;among them,4,10 and 4 cases received revision surgery.Another 13 patients of lumbar spinal stenosis were treated with revision surgery due to poor results after PTED in other hospitals.Among 31 cases of reoperation,there were 16 males and 15 females,aged 27-82 years (average,66.2±12.7 years).The lesion segments included 1 case of L3,4,23 cases of L4,5,5 cases of L5S1,1 cases of L3-L5,and 1 cases of L4-S1.Patients were followed up after reoperation from 3 to 24 months (average,12.1 months).The causes of poor result and revision surgery were analyzed according to preoperative,intraoperative and postoperative data.Results All of 757 cases of lumbar spinal stenosis were treated with PTED in three hospitals,of which 18 cases (2.4％) were re-operated.The causes of reoperation included:bone slice displacement in 1 case;nerve injury in 4 cases;lumbar instability in 4 cases;disc protrusion in 10 cases (residual or recurrence);insufficient decompression in 21 cases;planed staging operation in 4 cases with bilateral or two-level stenosis.32 revision surgeries were performed for 31 patients,including PTED in 15 cases,microendoscopic discectomy (MED) in 1 case,mobile MED (MMED) in 5 cases,MMED assisted fusion in 2 cases,transforaminal lumbar interbody fusion (TLIF) in 4 cases,Minimally invasive TLIF (Mis-TLIF) in 2 cases,and open decompression and fusion in 3 cases.All patients experienced relieve of symptoms after revision surgery.At final follow-up,VAS leg pain deceased form 7.1±3.9 before revision surgeries to 1.9±1.2,VAS low back pain decreased form 6.3±3.2 to 1.8±1.3,ODI score decreased from 35％± 14％ to 7.6％±5％.According to the MacNab score,the result was excellent in 11 cases,good in 16 cases,and fair in 4 cases.Conclusion The treatment of lumbar stenosis with PTED has high technical requirements,the indications of PTED for lumbar stenosis should be strictly controlled according to technical conditions,and appropriate operative methods should be chosen according to the specific conditions of the lesions.Insufficient decompression,disc protrusion,lumbar instability and nerve injury are the common causes of reoperation.Suitable indications and proper operation should be selected.

Objective Retrospective study and report on cases of "symptomatic facet of residual bone mass" caused by percutaneous transforaminal endoscopic discectomy (PTED),to analysis of its causes and revision strategies.Methods Seven cases of "symptomatic facet of residual bone mass" after PTED were found in six medical centers from July 2015 to November 2017.Weintroduced the course of diagnosis and treatment,to analysis of the causes,clinical features and revision strategies of the rare complication.Results Seven patients came from different medical centers (2 cases in Ningbo No.6 Hospital and 1 case in each of the other medical centers).The average age of the subject is 67.29±9.64 years (range from 57-83 years).Among them there were 1 male and 6 female.PTED was performed for all cases with lumbar disc herniation or stenosis.The operative segments were 1 of L2,3,2 of L3,4,3 of L4,5,1 of L5S1.Symptoms occurred immediately after surgery in all cases except one after a week of operation and another one month later.Two cases were appeared symptom of contralateral irritation,and the rest were aggravated by the original symptoms.Two cerebrospinal fluid leakage caused by bone mass piercing the dural sac.The bone mass compressed the nerve root and caused 1 case of lower limb muscle weakness.Foraminoplasty was performed during PTED in all patients.After CT scan,5 cases of bone mass were found on the same side of operation,and 2 cases were in the contralateral side.The shortest time for revision was 2 days and the longest 3 months.After conservative treatment,the symptoms were relieved in only one case.Revision surgeries were performed for all the other 6 cases,2 with microendoscopic discectomy (MED),1 mobile microendoscopic discectomy (MMED),1 small incision operation,1 PTED and 1 with minimal invasive surgery of transforaminal lumbar intervertebral fusion (MIS-TLIF).The VAS scores of low back pain and leg pain was significantly relieved from 8.67±0.52 to 1.50±0.55.Conclusion FTED may lead to residual bone mass in lumbar foraminoplasty.The penetration of the bone mass block into the spinal canal can cause the compression symptoms of the corresponding segment.The patients showed the corresponding spinal canal stenosis and nerve root irritation symptoms.A revision operation is required to remove the oppressed bone mass to relieve the symptoms as soon as possible if the conservative treatment not effective.

OBJECTIVETo evaluate the biomechanical effects of the anterior cervical transpedicular-screw system (ACTPS), compared to the anterior cervical screw plate system (ACLP), in the subaxial cervical spine after 2-level corpectomy.

METHODSA verified intact finite element subaxial cervical (C3-C7) model was established and analyzed by Mimics 10.0, Rapidform XOR3, Hypermesh 10.0, CATIA5V19, ANSYS 14.0 softwares based on the CT data (C1-T1) was collected from a 28 years old male volunteer. The axial force of 75 N and moment couple of 1N·m was loaded on the upper surface of C3, which made the model movement in flexion extension, lateral bending, rotating direction, respectively. Then, recorded the range of motion, and compared the results with the in vitro biomechanical experimental data to verify the effectiveness of the model. The ACTPS model and the ACLP model were analyzed using the finite element method. The range of motion at the operation segments (C4-C7), the range of motion at the adjacent segment (C3-C4) and stress distribution under flexion, extension, lateral bending, and axial rotation were calculated, and compared the range of motion with intact model.

RESULTSThere were 85,832 elements and 23,612 nodes in the intact model of subaxial cervical spine (C3-C7) in this experiment,and the range of motion of intact model validated with the reported cadaveric experimental data. In ACTPS group the stress was been well-distributed, but the stress concentrated on the interface between screw and the titanium plate in ACLP group. There were obvious differences of the maximum stress value between the two groups. The range of motion of fixed segments in ACTPS group was smaller than ACLP group, however adjacent segment range of motion showed no significant difference. Compared with the intact group, the range of motion in flexion extension, lateral flexion, rotation direction was decreased respectively about 25°, 20° and 8°, the range of motion at adjacent segment (C3-C4) was correspondingly compensated about 0.3°, 3° and 0.1°.

CONCLUSIONSACTPS is better than ACLP in terms of biomechanical properties. It offers rigid stability, and may be more suitable for reconstruction stability of 2-level and more than 2 levels corpectomy in the subaxial cervical spine. Meanwhile, the risk of fracture of ACTPS system is lower than that of the ACLP system.

Adult ; Biomechanical Phenomena ; Bone Screws ; Cervical Vertebrae ; surgery ; Finite Element Analysis ; Humans ; Male ; Models, Anatomic ; Range of Motion, Articular ; Rotation

Objective To explore the clinical outcomes of anterior plate fixation through transoral approach in the treatment of unstable atlas fractures.Methods From March 2004 to May 2010,20 patients with unstable atlas fractures were treated by anterior plate fixation through transoral approach,including 12 males and 8 females,aged from 23 to 68 years (average,47.7±13.9 years).Of the 20 cases of unstable atlas fractures,4 cases were classified as anterior 1/2 Jefferson fracture,8 cases as 1/2 ring Jefferson fracture,and 8 cases as anterior 3/4 ring Jefferson fracture.The preoperative average VAS scores were 6.0±1.3 points,ranged from 4 to 8 points.Clinical and imaging examinations were performed during follow-up period to evaluate the outcomes.Results All patients were followed up for 12 to 81 months,with an average of 48.5±20.0 months.There were no screw loosing and breakage,no plate displacement,and no spinal cord and vertebral artery injury during operation.A total of 20 plates were placed and all 40 screws were inserted into atlas lateral mass.Computed tomography scans demonstrated 2 screws were placed too close to the vertebral artery canal,but without clinical consequences.The postoperative VAS scores were from 0 to 3 points with an average of 1.3±1.0 points.Static and dynamic films 6 months after surgery demonstrated that fusion was achieved in all cases.Atlantoaxial rotational function was restored satisfactorily.No plate-related complication was observed in all patients in the whole follow-up period.Conclusion Anterior plate fixation through transoral approach is an effective method for management of unstable atlas fractures,which has advantages such as solid bony fusion and low incidence of complication.

Objective To investigate the preliminary clinical application of anterior pedicle screws in treatment of the lower cervical spine injuries. Methods The study involved 22 patients with lower cervical spine injuries treated with anterior pedicle screw technique from January 2009 to December 2011.X-ray and CT images of the patients were taken postoperatively to evaluate whether the position,orientation and length of the screws were appropriate and whether there involved pedicle cortex perforation,transverse foramen or spinal canal invasion.MRI was also performed to ascertain the situation of decompression,the formation of epidural hematoma and the degeneration of cervical spinal cord.The improvement of JOA score was compared statistically. Results All the patients were followed up for 3-36 months ( mean,15.5 months).A total of 44 anterior lower cervical screws were implanted and all screws were inserted smoothly.All the patients had bone healing after average 4.5 months,which showed no loosening,prolapse or breakage of the screws or no loosening of the plate.One patient showed hoarseness postoperatively,which was probably due to the long-term distraction of recurrent laryngeal nerve.The symptom disappeared at around three weeks after neurotrophic support.Two patients complained of dysphagia postoperatively,and were informed of keeping a soft diet.The symptom was remarkably alleviated after three months or so.The X-ray films indicated satisfactory position of the implanted screws.Before discharge,the transaxial CT images showed that two screws perforated the medial pedicle cortex ( 1 ° ) and that two screws perforated the lateral cortex (1 °) and affected the medial margin of the transverse foramen.Before discharge,the MRI indicated obvious alleviation of the anterior spinal cord compression in all patients and a small amount of anterior epidural hematoma in four patients,with no obvious spinal cord compression.At 12 months after operation,the MRI showed significant improvement of spinal cord degeneration in three patients.JOA score was increased from preoperative (8.5 ± 0.7) to ( 14.5 ± 0.8 ) before discharge (P ＜0.01 ).JOA score was (15.7 ±0.7) at six months postoperatively,which was significantly improved as compared with that before discharge. Conclusions Anterior pedicle screw fixation is a reliable and safe method for reconstruction of the anterior lower cervical injuries.Surgical indications should be strictly controlled in its clinical application.

ObjectiveTo evaluate the clinical effects of transforaminal lumbar interbody fusion (TLIF) or posterior lumbar interbody fusion(PLIF) using microendoscopic discectomy under X-Tube system in treatment of lumbar degenerative disc diseases.MethodsFrom December 2007 to April 2008,32 patients with low back disorders were treated by microendoscopic discectomy TLIF or PLIF under X-Tube system,including 19 cases in TLIF and 13 in PLIF.Etiologies including lumbar disc herniation combined with segmental instability in 21 cases,and spondylolisthesis in 11 cases.All patients were under regular postoperative follow-up and radiological examination.The clinical functional outcomes were evaluated according to Oswestry disability questionnaire.ResultsThe mean operation time was 120 min(range,90-180),and the average blood loss was 190 ml (range,100-400).There were no complications,such as infection and internal fixation failure.Bony fusion was achieved in all patients.The follow-up was from 14 months to 41 months with 21 months in the average.The average 0swestry scores decreased from preoperative 40.1％±4.1％ to 9.5％±3.7％ three months after the operation.The outcomes of this operation were rated as excellent.ConclusionMicroendoscopic discectomy TLIF or PLIF under X-Tube system in treatment of lumbar degenerative disc diseases has the characteristics of less blood loss,tissue trauma and quick recovery.