Objective To investigate the surgical indication,approach,resection methods and complications of total sacrectomy via posterior approach for primary malignant sacral tumors involving high level (S1,S2).Methods 5 cases of primary malignant sacral tumors treated by total sacrectomy via posterior approach and iliolumbar reconstruction from March 2010 to March 2011 were analyzed retrospectively.There were 3 males and 2 females.The mean age was 41,ranging from 32 to 55.The imageology examination showed osteolytic destruction,among which there were 4 cases of obvious soft tissue mass,1 case of obvious sacral foramina expansion with bone damage.MRI showed 1 case of the tumors in S1-S5,1 case of the tumors in S1 、S2,1 case of the tumors in S1-S3.The smallest tumor was 9.2 cm×7.6 cm×4.1 cm,while the largest was 22.0 cm× 19.0 cm× 16.0 cm.Preoperative TTNB were done on the 5 patients.Pathological diagnosis:2 cases of chordoma,1 case of malignant neurilemmoma,1 case of chondrosarcoma and 1 case of malignant hemangioendothelioma.5 patients had sacrococcygeal pain or lumbocrural pain before the surgery.Visual analogue scale (VAS):2 cases of 2,2 cases of 6 and 1 case of 8.Ilium stability reconstructions were all performed on 5 patients with spine pedicle screw-rod system.Results The mean operation time was 6.5 hours (range,4.5-11 hours),with the mean intraoperative blood loss of 3 700 ml (range,2 000-7 200 ml).There was no perioperative death.The mean follow-up time was 17 months (range,9-23 months).There were 2 cases of wound complications 2 weeks after surgery and healed by second intention with washing and drainage after debridement.There was no deep infection.1 case of rectal injury,which was performed with colostomy during the operation,and stoma returned 12 weeks after surgery.4 cases of sciatic nerve symptom of lower limbs and plantar flexion dyskinesia after bilateral S1 nerve roots resection.The patients walked with ankle brace fixed after the surgery.There was 1 case of implant breakage and no obvious spine down.5 patients had functional disability in sphincter after surgery.1 case of hemangioendothelioma recurred locally 9 months later.Local radiotherapy was performed since there was no reoperation indication.The patient is currently on the 13th month follow-up and survives with tumors.Compared with combined approach,the selection of posterior approach alone has relatively strict surgery indications.Conclusion Total sacrectomy via posterior approach is an effective way to treat the primary high-level malignant sacral tumors.The good surgical resection boundary is important to achieve the good oncology prognosis.The occurrence rate of postoperative complication is high,which has great influence on patients' postoperative neurological function.

Objectives:To investigate the clinical features and imaging characteristics of paralytic scoliosis secondary to spinal cord injury due to back-bend movements in dance training.Methods:The clinical and imaging data of patients with paralytic scoliosis secondary to spinal cord injury caused by back-bend move-ments in dance training who were admitted and treated surgically in Nanjing Drum Tower Hospital(division of spine surgery,department of orthopedic surgery)from June 2016 to August 2023 were retrospectively analyzed.All the patients underwent anteroposterior and lateral full spine X-ray examinations in sitting position.The ages of patients at the time of spinal cord injury,diagnosis of scoliosis and surgery were recorded.The planes of paraplegia,types of scoliosis,levels of involved segments,rotation of the apical vertebra,and pres-ence of hip dislocation were analyzed.The Cobb angle of the main curve of coronal scoliosis,pelvic obliquity angle(POA),and the angle of kyphosis were measured on anteroposterior and lateral X-ray films,and the flexibility of scoliosis was calculated.The correlation between the POA and Cobb angle of the main curve was analyzed as well.Results:A total of 19 patients were included in the study.All the patients were female aged 5-9 years(6.8±1.1 years)at the time of back-bend in dance causing spinal cord injury,6-11 years(8.6±1.3 years)at the time of diagnosis of scoliosis,and 10-26 years(13.2±3.9 years)at the time of surgery.All the patients were complete paralysis below the injury plane,which was at T10 level in 13 patients,T9 level in 2 patients,and T8 level in 4 patients.The main curve was all long C-type lumbar curvature or thoracolumbar curvature,and the number of segments involved in the main curve was 7-13(9±2),the Cobb angle was 50°-110°(74.2°±14.6°),and the flexibility of the main curve was 30％-54％(41％±10％).The apex rotation classified by Nash-Moe method fell in Ⅳ degree rotation in 12 cases,Ⅲ degree in 6 cases,and Ⅱ degree in 1 case.In sagittal plane,lumbar kyphosis was observed in 15 cases(78.9％);The local kyphosis angle was 27°-47°(34.3°±5.8°),and the lumbar lordosis angle was-47°-55°(-16.9°±34.1°);The thoracic vertebrae showed a compensated kyphosis reduction or even lordosis,with a thoracic kyphosis angle of-10°-25°(10.4°±9.1°).All the patients were complicated with hip subluxation,17(89.5％)patients among which were unilateral,and most were located on the concave side of the main curve;2(10.5％)patients were complicated with bilateral subluxation,which was more serious on the concave side of the main curve.All the patients had pelvic tilt,with a POA of 9°-39°(22.8°±8.4°).Pearson correlation analysis showed that there was a significant correlation between the POA and Cobb angle of main curve(r=0.635,P＜0.05).Conclusions:Pa-tients with paralytic scoliosis secondary to spinal cord injury due to back-bend movements in dance training present with a long C-type lumbar curve or single thoracolumbar curve,which has a large curve span,long segments involvement,severe vertebral rotation,relatively soft deformity,and short compensatory curve at the proximal end of the main curve.All the patients are combined with pelvic tilt and hip subluxation on the concave side of the main curve.Pelvic tilt is positively correlated with the severity of scoliosis.In the sagittal plane,a compensatory decrease in the thoracic kyphosis is manifested,and lumbar or thoracolumbar kyphosis is presented.