Objective To compare the clinical and radiological outcomes between hybrid and total pedicle screw instrumentation in adolescents undergone posterior spinal fusion (PSF) for thoracic scoliosis secondary to Chiari malformation..Methods A total of 75 patients undergone PSF were included and divided into two groups:the all pedicle screw group (Group A,n=44) and the hybrid group (Group B,n=31).Patients were evaluated before surgery,immediately after surgery,and at the 2-year follow-up in radiographic changes in curve magnitude,apical vertebral translation (AVT),apical vertebral rotation (AVR),trunk shift,thoracic kyphosis (TK),lumbar lordosis (LL),and sagittal vertical axis (SVA).These parameters were further analyzed with respect to preoperative TK in both groups.Results After surgery,the average correction of the thoracic curve was 60.2％ and 51.3％ in Group A and B,respectively (t=2.372,P=0.023).The average lumbar curve correction was 61.7％ in Group A,representing a significant increase compared to Group B (51.1％,t=2.431,P=0.020).At the final follow-up,loss of the thoracic curve correction was less in Group A (0.3％) than in Group B (1.7％),however,there was no statistical significance (t=-0.468,P＞0.05).AVT of the thoracic curve improved in Group A from 25.0 mm to 6.9 mm,while in Group B it changed from 24.1 mm to 7.4 mm.For patients with a preoperative TK greater than 40°,the proximal junctional angle was found to be significantly larger in Group A (10.0 degrees versus 4.5 degrees,t=-2.031,P=0.052) by the final follow-up,along with a significantly increased incidence of proximal junctional kyphosis (20％ versus 9％).Conclusion Total pedicle screw instrumentation provided a significantly better correction of the major and minor curves than hybrid constructs for the operative treatment of thoracic scoliosis secondary to Chiari malformation.However,for patients with thoracic hyperkyphosis,all-screw instrumentation had a higher risk of adjacent level proximal kyphosis.

Objective To explore the feasibility and efficacy of posterior minimally invasive scoliosis surgery in Lenke 5C adolescent idiopathic scoliosis (AIS).Methods From November 2012 to March 2014,a total of 16 patients underwent posterior minimally invasive scoliosis surgery assisted by O-arm three-dimensional CT navigation were included.There were 14 female and 2 male,with an average age of (16.7± 1.6) years (ranged from 14 to 18 years).The mean Cobb angles of lumbar and thoracic curve were 48.7°±5.6°and 24.1°±5.4°,respectively.Results 16 patients were successfully completed the operation,the average operation time was (246±89) min,the average intraoperative blood loss was (192± 105) ml,and the fusion level was 4.9±0.5 on average.A total of 155 screws were inserted in the 16 patients,with a mean implant density of 98.9％±4.9％.All the patients were followed up for (26.4±3.9) months on average.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.SRS-22 scores and complications were also recorded during the follow-up.Immediately after surgery,the correction rate of main lumbar curve was 80.1％±8.3％,and thoracic curve was 59.3％±8.7％,and a obvious improvement was noted in terms of AVT,AVR,trunk shift and TLK.At the last follow-up,except the increase of SVA from (-27.6± 19.5) mm to (-12.3±6.6) mm,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％ (9/155).Fusion across the facet joint were satisfactory.In SRS-22 assessment,the mean scores of functional,pain,self-image,mental state and satisfaction were (4.3 ± 0.5) points,(4.7 ± 0.6) points,(4.2 ± 0.7) points,(4.2 ± 0.5)points and (4.4 ± 0.6) points.No wound infection,implant failure and neurologic complications were found after surgery.Conclusion Wiltse approach assisted by O-arm three-dimensional CT navigation has the characteristics of small injury,less bleeding,high accuracy placement of pedicle screws and high self-satisfaction of patients.It is a feasible,safe and effective way to treat Lenke 5C AIS.