243+1.153*age. CONCLUSIONS PI was not a fixed but a dynamic parameter in the population under 12 years old. Indeed, PI increases with age and bone maturity in childhood. We also found lower PI, PT and SS compared with published studies of adolescents in other countries. These results may aid in the treatment of patients with spinal deformity, to help them achieve a certain degree of sagittal spinopelvic balance. LEVEL OF EVIDENCE 2.STUDY DESIGN A retrospective study. OBJECTIVE Investigate the diagnosis and surgery strategy for treatment of development spinal canal stenosis (DSSA) at atlas plane based on CT image characters. SUMMARY OF BACKGROUND DATA The occurrence of spinal canal stenosis in the atlas plane is relatively rare compared with lower cervical. METHODS 15 patients diagnosed with DSSA were included from 2014 to 2018. They are divided into 4 subgroups based on the character of CT images group I (small size atlas), group II (hypertrophy of PAA), group III (incurved of PAA) and group IV (hypertrophy odontoid). RESULTS There are type I 7, type II 3 type III 2 and group IV 3 in the 15 cases. All the patients received different surgery procedures respectively ①posterior arch osteotomy were performed for group I/III//IV without atlantoaxial dislocation, ② posterior arch resect and replantation were performed for group II ③ occipital cervical fixation and fusion were added to the patients with associated AAD. ④ a new method of odontoid reduce and atlantoaxial fixation by transoral approach were performed for group IV with associated AAD. All cases underwent surgery successfully which included OCF+PAR 8cases, PAR 4 cases, PAR R2 cases and DR+TARP 1 case without severe complications. All patients show different improvement in the symptoms. JOA scores improved from 9.2 to 14.7 in 1year follow-up. CONCLUSION DSSA could be easily diagnosed and divided into 4 subgroups according to the character of CT image, corresponding surgery strategy could receive a fine clinical result. LEVEL OF EVIDENCE 4.STUDY DESIGN Multicenter, prospective randomized study. OBJECTIVE Evaluate the impact of weekly teriparatide (WT) and bone contact (BC) status of grafted bone in patients recovering from multi-level lumbar interbody fusion (M-LIF). SUMMARY OF BACKGROUND DATA WT has been reported to significantly improve bone fusion following posterior or transforaminal interbody fusion in osteoporosis patients. METHODS Patients older than 50 years and osteoporotic were recruited. We defined the fusion of 2 or more consecutive intervertebral levels as M-LIF. All patients were instrumented with pedicle, iliac, or S-2 alar iliac screws after transplanting cages and autogenous bone between vertebral bodies. After surgical indication for M-LIF, the subjects were randomly allocated to receive either subcutaneous WT from 1 week to 6 months postoperatively (WT arm, N = 50) or a bisphosphonate (BP; BP arm, N = 54). Blinded radiological evaluations were performed using computed tomography (CT). Evaluation of bone fusion was performed at the intervertebral disc located at the bottom of the fixed range. The degree of bone fusion was calculated as a score from 2 to 6 points, with 2 defined as complete fusion. Bone fusion rate was also compared at 6 months postoperatively based on BC status of the grafted bone on CT immediately after surgery. RESULTS Mean bone fusion score at 6 months postoperatively was 3.9 points in the WT group and 4.2 points in the BP group. The bone fusion rate at 6 months postoperatively tended to be higher in the WT group (46.8% vs. 32.7% in the BP group). The 6-month postoperative fusion rate of immediately postoperative of BC+ patients was significantly higher than that of BC- patients (47.4% vs. 9.5%). CONCLUSION In M-LIF, there were no significant differences in bone fusion score between WT- and BP-treated patients. In contrast, BC status immediately postoperatively had a major impact on 6-month bone fusion. Galunisertib clinical trial LEVEL OF EVIDENCE 1.STUDY DESIGN Retrospective case analyses. OBJECTIVE The aim of this study was to investigate the incidence and characteristics of associated upper cervical spine injuries in 15 survival cases of traumatic atlanto-occipital dislocation (AOD). SUMMARY OF BACKGROUND DATA Traumatic AOD is a rare and generally fatal injury. Information regarding associated upper cervical spine injuries that may affect treatment methods, outcomes, and prognosis is limited. METHODS Fifteen patients (11 patients with posterior-type AOD and four patients with vertical-type AOD) who survived traumatic AOD were included in this study. Plain radiographs, computed tomography, magnetic resonance imaging, and medical records were reviewed. The incidence and characteristics of associated upper and lower cervical spine and thoracolumbar spine injuries and brain injuries were evaluated. RESULTS Thirteen patients with traumatic AOD (11 patients with posterior-type AOD and two patients with vertical-type AOD) showed associated upper cervical spier cervical spine injuries and brain injuries in traumatic AOD, which affects treatment, outcome, and prognosis. LEVEL OF EVIDENCE 4.STUDY DESIGN Cohort study (level 3). OBJECTIVE To identify independent risk factors for residual low back pain (LBP) following osteoporotic vertebral fracture (OVF). SUMMARY OF BACKGROUND DATA Non-union has been proposed as the primary cause of residual LBP following OVF. However, LBP can occur even when union is maintained. Other reported causes of LBP after OVF include vertebral deformities and spino-pelvic malalignment. METHODS Sixty-seven patients with single-level thoracolumbar OVF who had not received previous osteoporotic treatment were enrolled. Conservative treatment was conducted using a soft lumbosacral orthosis plus osteoporosis drugs, either weekly alendronate (bisphosphonate) or daily teriparatide. Pain scores, kyphosis angle of fractured vertebra (VKA), and spino-pelvic alignment, including pelvic incidence minus lumbar lordosis (PI-LL), were assessed periodically during treatment. Radiographic union was evaluated independently by three specialists at 24 weeks post-admission. Patients were divided by pain scores >40% at 24 weeks into the LBP (n = 36) and non-LBP (n = 31) groups.