Changes in Level of the Conus after Corrective Surgery for Scoliosis: MRI-Based Preliminary Study in 31 Patients

BACKGROUND: Detection of postoperative spinal cord level change can provide basic information about the spinal cord status, and electrophysiological studies regarding this point should be conducted in the future. METHODS: To determine the changes in the spinal cord level postoperatively and the possible associated factors, we prospectively studied 31 patients with scoliosis. All the patients underwent correction and posterior fusion using pedicle screws and rods between January 2008 and March 2009. The pre- and postoperative conus medullaris levels were determined by matching the axial magnetic resonance image to the sagittal scout image. The patients were divided according to the change in the postoperative conus medullaris level. The change group was defined as the patients who showed a change of more than one divided section in the vertebral column postoperatively, and the parameters of the change and non-change groups were compared. RESULTS: The mean pre- and postoperative Cobb's angle of the coronal curve was 76.80degrees +/- 17.19degrees and 33.23degrees +/- 14.39degrees, respectively. Eleven of 31 patients showed a lower conus medullaris level postoperatively. There were no differences in the pre- and postoperative magnitude of the coronal curve, lordosis and kyphosis between the groups. However, the postoperative degrees of correction of the coronal curve and lumbar lordosis were higher in the change group. There were also differences in the disease entities between the groups. A higher percentage of patients with Duchene muscular dystrophy had a change in level compared to that of the patients with cerebral palsy (83.3% vs. 45.5%, respectively). CONCLUSIONS: The conus medullaris level changed postoperatively in the patients with severe scoliosis. Overall, the postoperative degree of correction of the coronal curve was higher in the change group than that in the non-change group. The degrees of correction of the coronal curve and lumbar lordosis were related to the spinal cord level change after scoliosis correction.

Comparison of Apical Axial Derotation between Adolescent Idiopathic and Neuromuscular Scoliosis with Pedicle Screw Instrumentation

STUDY DESIGN: A retrospective study. PURPOSE: To compare outcomes of apical derotation with pedicle screws in idiopathic and neuromuscular scoliosis (NMS). OVERVIEW OF LITERATURE: No information about apical derotation in NMS with pedicle screws is available. METHODS: We performed deformity correcting surgery using pedicle screw constructs on 12 adolescent idiopathic scoliosis (AIS) patients (mean age 14.1 years) and 16 NMS patients (mean age 16.5 years). Preoperative, postoperative, and final follow-up radiographs were analyzed for Cobb's angle and pelvic obliquity, while apical rotation was measured on CT scans using the Aaro-Dahlborn method. RESULTS: For AIS, the mean preoperative Cobb's angle, pelvic obliquity, and apical rotation values were 57.3degrees, 2.8degrees, and 20.4degrees, respectively, and postoperatively they were 16.8degrees, 1.1degrees and 14.7degrees, respectively, showing significant correction. For NMS, the mean preoperative Cobb's angle, pelvic obliquity, and apical rotation values were 75.6degrees, 13.7degrees, and 42.9degrees, respectively, and postoperatively they were 27.1degrees, 5.8degrees, and 34.1degrees, respectively, also showing significant correction. There were no significant differences between AIS and NMS patients Cobb's angle p=0.306, pelvic obliquity p=0.887 and apical derotation p=0.113degrees. There were no differences in curve severity in the three groups (AIS, NMS >80degreesand NMS 80 NMS group (p=0.04). CONCLUSIONS: Apical axial derotation can be achieved with posterior only pedicle screw fixation in NMS without anterior release, with comparable results in idiopathic scoliosis.