Dmineralized Bone Matrix Incorporated With CBD-BMP-2 To Accelerate Spinal Fusion At Low Dose In Rat And Surgical Treatment For Spinal Deformity

Chapter 1(section 1)Dmineralized bone matrix incorporated with collagen-binding bone morphogenetic protein-2 to accelerate spinal fusion at low dose in ratObjective:To investigate the feasibility and efficacy of a delivery matrix using demineralized bone matrix(DBM)incorporated with collagen-binding bone morphogenetic protein-2(CBD-BMP-2)in the rat inter-transverse spinal fusion model.Methods:60 rats undergoing posterolateral(inter-transverse)spinal fusion were divided into 3 groups according to the fusion materials containing different components(n=20 per group).Group A were implanted with DBM,Group B with combination of DBM and BMP-2 and Group C with combination of DBM and CBD-BMP-2.After surgery,the spinal fusion of all the rats was assessed by plain radiography,CT + 3D reconstruction,manual palpation and histological evaluation.Results:Significant difference was found in terms of solid fusion rate among the three groups,with 95%in Group C,65%in Group B and 0%in Group A(P<0.001).Compared with Groups B and A,new bone formation was observed earlier and was obvious larger,trabecular bone microarchitecture assessment was better and bone mineral density was statistically larger in Group C.In addition,more newly woven bone and osteocytes were showed by histological evaluation in Group C at 4 week post-operation.Conclusions:CBD domain could help BMP-2 to improve the efficiency of posterolateral spinal fusion.DBM scaffold activated by collagen-binding BMP-2 was a feasible and promising bone repair vehicle.Chapter 2(section 1)The influence of posterior correction and fusion surgery on the sagittal spinopelvic alignment in sitting position in adolescents with idiopathic scoliosisObjective:To assess the influence of posterior correction and fusion surgery upon sitting sagittal spinopelvic alignment in adolescents with idiopathic thoracic curves(T-AIS).Methods:44 subjects with T-AIS(30 Lenke I and 14 Lenke II)at our center were included.Pre-and postoperative long-cassette lateral radiographs of the spine and pelvis were obtained in standing and sitting.Thoracic kyphosis(TK),lumbar lordosis(LL),pelvic incidence(PI),sacral slope(SS),and pelvic tilt(PT)were measured on standing and sitting lateral radiographs.Patients were divided into selective thoracic fusion(STF)and nonselective thoracic fusion(NSTF)groups.Results:At baseline,TK,LL and SS decreased by 27.5%,42.1%and 31.1%,respectively,while PT increased by 193.6%from standing to sitting.After posterior spinal fusion,increased TK,LL,and SS and corresponding decreased PT were observed compared to baseline parameters in sitting position.In the whole cohort,LL and SS in sitting significantly decreased by 14.0%and 13.9%,respectively,while PT in sitting was significantly increased by 39.0%,when comparing with standing values.Similar changes were also observed in STF group:LL was decreased by 15.6%and SS was decreased by 11.5%when seated.However,no obvious changes of the postoperative values in sitting were found in NSTF group.Conclusions:Posterior correction and fusion surgery in T-AIS patients diminished the ability of spinal straightening and pelvic retroversion when sit.Reducing distal fusion levels was not only of special value in saving more lumbar mobility,but also preserving the function of pelvic posterior rotation.Chapter 2(section 2)Posterior minimally invasive scoliosis surgery for adolescent idiopathic scoliosis:a feasible and effective optionObjective:To explore the feasibility and assess the preliminary outcomes of posterior minimally invasive scoliosis surgery(MISS)in adolescent idiopathic scoliosis(AIS).Methods:A total of 16 patients underwent posterior MISS assisted by O-arm navigation were included.They were 14 females and 2 males,with an average age of 16.5±1.6years.The operation time and intraoperative blood loss were recorded.The following radiographic parameters were evaluated before surgery,immediately after surgery and at the last follow-up:curve magnitude,apical vertebral translation(AVT),apical vertebral rotation(AVR),trunk shift,thoracic kyphosis(TK),thoracolumbar kyphosis(TLK),lumbar lordosis(LL)and sagittal vertical axis(SVA).The accuracy of pedicle screw placement was assessed according to postoperative CT scans.Screw perforation>2mm of either pedicular or vertebral cortex was considered at potential risk,and medial pedicle perforation>4mm or contour of aorta was considered at high risk.Results:The average operation time was 2461±89 min and intraoperative blood loss(EBL)was 292±105 ml on average.A total of 155 screws were inserted in the 16 patients.The Cobb angle of thoracolumbar/lumbar curve was 48.7±5.6° degrees before surgery.Immediately after surgery,the correction rate of main curve was 80.1 ±8.3%on average,and a obvious improvement was noted in terms of AVT,AVR,trunk shift,TK and TLK.All the patients were followed up for 26.4±3.9months on average.At the last follow-up,the average loss of correction of the main curve was 2.9%(0-6.0%).Except the increase of SVA(from-27.6± 19,5mm to-12.3±6.6mm),no obvious changes of AVT,AVR,trunk shift,TK,TLK and LL were observed during the follow-up.According to CT evaluation,the satisfactory rate of pedicle screw placement was 94.2%,while the perforation rate was 5.8%.Fusion across the facet joint and SRS-22 assessment were satisfactory.No wound infection,implant failure and neurologic complications were found after surgery.Conclusion:Posterior MISS is a feasible and safe option for patients with AIS,with less truma,less EBL,high accuracy placement of pedicle screws and high self-satisfaction.Although the short-term results showed multiple benefits,long term data is needed before routine use.Chapter 2(section 3)Posterior minimally invasive scoliosis surgery for adolescent idiopathic scoliosis:a comparison with standard open approach spinal instrumentationObjective:To compare the outcomes of posterior minimally invasive scoliosis surgery(MISS)assisted by O-arm navigation and standard open approach spinal instrumentation for the correction of Lenke type 5C AIS.Methods:A total of 15 Lenke 5C AIS patients who underwent posterior MISS under O-arm navigation and 30 Lenke 5C AIS patients who underwent posterior spinal fusion(PSF)were recruited at our center.The levels of fusion,density of implants,operation time and estimated blood loss(EBL)were recorded.The coronal and sagittal parameters were evaluated before surgery,immediately after surgery and at the last follow-up.The accuracy of pedicle screw placement was assessed according to postoperative axial CT images in both groups.Scoliosis Research Society 22(SRS-22)questionnaires and complications were collected during the follow-up.Results:The MISS group and PSF group were matched in terms of baseline characteristics.Comparison of radiographic parameters showed no obvious difference between the two groups immediately after surgery or at the final follow-up.However,MISS patients had significantly less EBL(P<0.001)and more operation time(P=0.002).The evaluation of pain and self-image through SRS-22 questionnaire was significantly higher in MISS group than in PSF group(P=0.013 and P=0.046).Postoperative CT scan showed high accuracy of pedicle placement in both groups.No deep-wound infection,pseudarthrosis,additional surgery,implant failure or neurologic complications was recorded in either group.Conclusions:Compared with the open approach,posterior MISS surgery could achieve similar and satisfactory results in the treatment of adolescent idiopathic scoliosis.Chapter 2(section 4)Posterior correction and fusion surgery for adolescents with scoliosis secondary to Chiari I malformation in the absence of syringomyeliaPurpose:To investigate the safety and effectiveness of posterior correction and fusion surgery in adolescents with scoliosis secondary to CMI in the absence of SM and to explore the influence of correction surgery upon the natural evolution of cerebellar tonsil in these patients.Methods:A total of 14 patients meeting the inclusion criteria at our spine center from 2010-2015 were enrolled in this study.One-stage posterior correction and fusion with segmental pedicle screw instrumentation was performed for all patients without additional neurosurgical intervention for their Chiari malformation.Patients' medical records(age,gender,length of follow-up,neurologic signs and symptoms),intraoperative neuromonitoring(SEP and MEP),MRIs measurement(cerebellar tonsillar position)and radiographic studies were reviewed.Results:The mean age of the 14 patients at the time of surgery was 15.8 ± 4.3 years.The primary curve magnitude averaged 61.71 ± 20.93° and the cerebellar tonsillar position averaged 8.81±2.58 mm(3 Grade II and 11 Grade I)below foramen magnum preoperatively.Throughout operation,no neuromonitoring difficulties(lack of baseline or loss of signal)were observed.Immediately after operation,the mean percent correction was 67.76 ± 11.57%of the major curve.During follow-up,the deformity correction was maintained satisfactorily and neural physical examination of each patient was not worse than the preoperative situation.MRIs at 2 year follow-up showed that the mean value of tonsillar position was 6.32±2.75 mm(range 2.14-11.66 mm)below foramen magnum,with cerebellar tonsil upward shifting was observed in 10 patients(71.43%),whereas downward shifting in 4 patients(28.57%).In addition,no complications of deep-wound infection,pseudarthrosis,additional surgery or implant failure in this group were found.Conclusion:Posterior correction and fusion surgery is a safe and effective procedure for treatment of scoliosis associated with only CMI,with satisfactory correction on coronal and sagittal planes without neurologic problems.At 2-year follow-up,more than half of cerebellar tonsils shifted upwardly,which indicated that the behavior of cerebellar tonsils after correction surgery was usually benign.Chapter 2(section 5)Posterior correction and fusion surgery for adolescent Scheuermann hyperkyphosis:selection of optimal distal fusion levelObjective:To explore the necessity of fusion to sagittal stable vertebra(SSV)in patients with Scheuermann kyphosis(SK)undergoing posterior correction and fusion surgery with all pedicle screw instrumentation.Methods:45 patients with SK needed surgical intervention at our center were involved and were randomly assigned into two groups:Group FLV(first lordotic vertebra,n = 24):fusion to FLV;Group SSV(n = 21):fusion to SSV.All the patients included underwent posterior correction surgery with all pedicle screws construct.Whole spine x-rays obtained before surgery,immediately after operation,and at the latest follow-up were analyzed.The following parameters were measured and compared between the two groups:Global kyphosis(GK),lumbar lordosis(LL),Sagittal balance(SVA),the distance from the center of the LIV to the posterior sacral vertical line(LIV-PSVL)and the development of distal junctional kyphosis(DJK)during the follow up.Results:The two groups of 45 patients were comparable in age,gender,BMI and sagittal parameters.GK was significantly decreased after surgery(P<0.001)and maintained up to final evaluation for the whole cohort.Between the two groups,postoperative GK,LL and SVA and correction rate of GK were similar and did not differ as well in the final follow-up.No significant difference was found in the occurrence of radiographic DJK,with 3 patients in Group FLV and 2 patients in Group SSV.Conclusion:Fusion to the SSV is not necessary and relatively less fusion levels stopped at FLV could yield a promising outcome for SK patients undergoing posterior correction and fusion surgery with all pedicle screws construct.