Objective To investigate the clinical results of bilateral transpedicular kyphoplasty for the osteoporotic vertebral compression fractures with single balloon. Methods From March 2002 to February 2004, percutaneous bilateral transpedicular kyphoplasty with single balloon was performed in 15 patients, who presented with painful vertebral compression fractures. In the group, there were 6 vertebrae of 6 males and 11 vertebrae of 9 females, and the average age of the patients was 70.5 years with a range of 62 to 82 years. 17 osteoporotic vertebral compression fractures, which involved 8 T12, 7 L1, 1 T8 and 1 T11, were treated. Osteoporosis was identified in all cases by the measurement of lumbar bone mineral density (BMD) and the evaluation of radiographs. The average BMD was 0.603 g/cm2. CT scan showed the posterior vertebral wall intact in all patients, and MRI displayed low signal on T1WI and high signal on T2WI of the vertebral fractures. Results All patients experienced dramatic pain relief after the procedures. The mean pain score (VAS) decreased significantly from 8.3 preoperatively to 2.1 after operation. The mean vertebral body height restoration was 54.2%?34.1% on the anterior border, 60.5%?35.4% in the middle portion, and 40.7%?32.3% on the posterior border respectively. And the sagittal alignment was improved significantly, as the average correction of the Cobb's angle reached 9.5?. No cement leakage was found on X-ray, except one with less cement at the anterior vertebral edge, but no clinical symptom occurred. All the patients were available at the final follow-up, the mean period was 10.5 months (range, 2-48 months). Conclusion Bilateral transpedicular kyphoplasty with single balloon not only can provide effective pain relief and vertebral height restoration, but also can improve the sagittal alignment significantly. Its clinical outcome was satisfactory.

ObjectiveTo investigate application of the anterior cervical pedicle screw in the lower cervical spine.MethodsTwenty disarticulated human vertebrae(C3-C7) were evaluated with computed tomography for pedicle morphometry Parameters included vertebral body height,vertebral body depth,vertebral body width,outer pedicle width,outer pedicle height,pedicle axis length,transverse section angle,sagittal section angle,transverse intersection point distance and sagittal intersection point distance.On the basis of these data,the screw channel was determined and the screws were inserted in the specimen.Five patients underwent surgical reconstruction using anterior pedicle screw fixation.After surgery,physical examination and roentgenograms and CT scans were performed in all patients.ResultsThe transverse section angle increased from C3(45.7°±4.0°) to C5(52.1°±5.9° ),but decreased from C6(47.8°±6.7°) to C7(44.4°± 8.3°).The sagittal section angle gradually increased from C3 (93.4°±7.2°) to C6( 112.1°±6.2°) but decreased a little to C7(102.7°±8.5°).The distances in transverse section was about 1.97-3.98 mm and in sagittal section was 3.4-7.5 mm.Anterior pedicle screws were inserted successfully in all specimens without critical pedicle wall perforations.Patients were permitted to ambulate the next day after surgery with a cervical collar.Postoperative neurological improvement was observed in all cases.Postoperative radiographic evaluation confirmed proper insertion of anterior pedicle screws without pedicle perforaton.The average follow-up time was 10.6 months.No anterior pedicle screw breakage and loosening was observed.ConclusionThe entry point in anterior pedicle screw should located in 5mm to upper endplate and near anterior median line.The transverse section angle should be 45.7°-52.1°and the sagittal section angle should be 93.4°-112.1°.The lengths of the screw should be about 32 mm.

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.

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 discuss the strategies for treatment of lower cervical distractive flexion injuries. Methods Sixty-eight patients including 43 males and 25 females at age range of 18-72 years (average 43 years) suffered from lower cervical distractive flexion injuries were operated from January 2002 to June 2007. According to Allen's classification, there were 7 patients at grade Ⅰ, 19 at grade Ⅱ,29 at grade Ⅲ and 13 at grade Ⅳ. Temporary skull traction was used for each subject before surgery. Only posterior approach was performed in 26 patients who were fixated by pedicle screw system,lateral mass screw system or transarticular screw system. Combined anterior and posterior approach was applied for the other 42 patients at one stage. The curative effect was followed up for all patients after the procedures. Results All patients were followed up for 6-65 months ( average 34 months), which showed posterior incision infection in 2 patients who were cured after debridement or change dressing. Two patients with aggravated neural symptome were cured following treatment with methylprednisolone. Neural function was improved at least for one level in all patients except for 18 patients (Frankel A). Of 11 patients at grade B, there were 4 patients improved to grade C and 5 to grade D. Of 10 patients at grade C, there were 6 patients recovered to grade D and 4 to grade E. All 15 patients at grade D reached grade E. It was not found loosening, breakage or defuxion. The graft bone was fused within 3-4 months, with no any complications related to surgical fixation. Conclusions The strategies for lower cervical distractive flexion injuries should be taken according to Allen' s classification. Single posterior procedure is suitable for grade Ⅰ and Ⅱ injuries. While combined posterior and anterior procedure can be used for grade Ⅲ and Ⅳ injuries.

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 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 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.

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.