Clinical Research Of Thoracic Pedicle Screw System For Correction Of Adolescent Idiopathic Scoliosis And MRI Pedicle Morphology Analysis

Objective1. To discuss the efficacy of all pedicle screws applied in surgical treatment for adolescent idiopathic scoliosis. To compare with hook-screw system, we evaluate the safety and advantages of all pedicle screw technique in correction of AIS.2. To determine the position of the thoracic pedicle screws applied in surgical treatment for adolescent idiopathic scoliosis with CT scan. So that it can be evaluated that the safety of a free hand technique of pedicle screw placement in the thoracic spine in the treatment of AIS.3. To use magnetic resonance imaging to assess pedicle asymmetry in normal people and patients with adolescent idiopathic scoliosis in the early stages of scoliosis development and to determine if patients with adolescent idiopathic scoliosis exhibited a consistent vertebral morphology.Methods1. Fifty-six AIS type Lenke 1 patients who received all pedicle screw correction and 43 AIS patients who underwent correction by pedicle hooks, laminar hooks combined with lumbar pedicle screws were compared. The efficacy of all pedicle screw with corrective rate of major curve, spontaneous corrective rate of compensate curve and loss of correction were evaluated.2. Thirty-five AIS type Lenke 1 patients underwent posterior stabilization utilizing transpedicular thoracic screws were reviewed. After operation, screws inserted into the deformed thoracic spine were evaluated by thoracic computed axial tomography(CAT) to assess for screw position, and with follow-up to evaluate the the safety of free hand technique.3. To use magnetic resonance imaging to assess pedicle asymmetry in normal patients and patients with adolescent idiopathic scoliosis in the early stages ofscoliosis development. Recorded parameters included pedicle lengths, pedicle widths, pedicle areas, pedicle perimeters, and lamina lengths. The extent and direction of asymmetry in vertebrae from normal people and patients with adolescent idiopathic scoliosis were determined and compared.Results1. In the all pedicle screw group of posterior correction of thoracic adolescent idiopathic scoliosis, the corrective rate of major curve was 73.50 % , spontaneous corrective rate of lumbar compensated curve was 74.26%, corrective rate of trunk shift was 73.60% and loss of correction was 1.89°, which was better than control group 65.46%, 60.17%, 70.75% and 3.29° respectively. There was no statistically difference between the two groups on the restoration of saggital plane. In the 13 patients whose curve type and curve magnitude were coincidental, there were 10 patients saved 11 segments compared with control group, 3 cases' fusion levels were identical. Average saving levels were 0.85 segments.2. Six out of 326 thoracic pedicle screws evaluated by thoracic CAT scan showed medial cortical wall violation between 2.5 to 5.0 mm. There were 13 screws inserted with moderate lateral cortical perforation between 3.0 to 6.0 mm. There were no screws (out of the entire study group of 326 thoracic pedicle screws) with any neurologic, vascular and visceral complications after operations or at follow-up.3. To use magnetic resonance imaging to assess pedicle asymmetry in normal people and patients with adolescent idiopathic scoliosis in the early stages of scoliosis development. Normal people displayed significant asymmetry in neural arch length, with the left pedicle and lamina length being significantly greater. In the population of patients with AIS, the neural arches were also significantly asymmetric. In comparing the extent of asymmetry to the normal population, the patients with AIS showed greater asymmetry. However, this asymmetry did not reach significant levels. Furthermore there was no consistent distribution of this asymmetry between the convex and the concave sides of the curve. In dividing the patients with AIS into subsets, In the primary curve, the pedicle on the convex side and the lamina on the concave side were significantly longer on average thantheir counterparts, whereas in secondary curves, the pedicle on the concave side and the lamina on the convex side were significantly longer. Conclusion1. Compared with hook-screw correction group, the all pedicle screw group has better coronal correction, spontaneous compensated curve correction and loss of correction. And the complication comeing from pedicle screws fixation did not increase. All pedicle screw technique could efficiently save motion segments compared with previous corrective strategy which suggested fusing to stable vertebra applied with hybrid system, and could avoid progression of lumbar curve.2. Free hand technique is a safe method of thoracic pedicle screw placement in the treatment of AIS. But we think this method may not be the best for many surgeons. It is only fit for very experienced spinal surgeons.3. Pedicle asymmetry in normal people and patients with adolescent idiopathic scoliosis in the early stages of scoliosis development was assessed. The fact that the left pedicle and lamina were greater in length than the right pedicle and lamina in normal patients is significant and strongly suggests that the baseline used to characterize AIS vertebral morphology should be re-evaluated. The population of AIS patients also displayed significant asymmetry. However, the direction of this asymmetry was not consistent. This would suggest that the patterns of vertebral morphology in AIS might depend on the specific cause.