| Chapter1Association of rs11190870near LBX1with adolescent idiopathic scoliosis susceptibility in a Han Chinese populationObjective:To investigate whether rs11190870near LBX1correlates with the susceptibility or curve progression of adolescent idiopathic scoliosis (AIS) in a Han Chinese population.Method:A total of949AIS patients and976age-matched healthy controls were recruited. All the subjects were genotyped using the PCR-based Invader assay. Case-control study and case-only study were performed to define the contribution of rs11190870to predisposition and curve severity of AIS. Additionally, we further conducted a meta-analysis of the study findings together with those of previously reported studies.Results:A significant association of rs11190870with AIS was observed in the Han Chinese population (P=1.8×10-9; odd ratio=1.51;95%confidence interval=1.33-1.71), and AIS patients with TT genotype had a larger Cobb angle than those with TC or CC genotype (P=0.005). The meta-analysis confirmed that the positive association of this SNP with AIS in the East Asian population.Conclusion:The SNP rs11190870near LBX1is associated with both susceptibility and curve progression of AIS.Chapter2(section1) The position of the aorta changes with altered body position in single right thoracic adolescent idiopathic scoliosisObjective:To explore the differences in the position of the aorta relative to the spine in patients with single right thoracic adolescent idiopathic scoliosis (RT-AIS) in two different body positions (supine and prone).Methods:Twenty-six patients with single RT-AIS were recruited into the present study. Each patient received an axial MR scan from T5through L3in both the supine and prone positions. In the Cartesian coordinate system, the left pedicle-aorta (LtP-Ao) angle, LtP-Ao distance and vertebral rotation angle were measured from T5through L3in the axial plane MR images. The paired Sample t-test was used to compare these parameters between the two body positions.Results:The mean LtP-Ao angle and mean LtP-Ao distance differed between the body positions at each level. At the T5-T10levels, the patients in the prone position exhibited significantly smaller LtP-Ao angles (26.2°vs.38.8°; P<0.01) and distances (27.0mm vs.30.7mm; P<0.01) than those in the supine position. The vertebral rotation angle was larger in the prone position than in the supine position at periapical levels, although this difference did not reach statistical significance (P>0.05).Conclusion:The aorta shifts more anteromedially and more closely to the spine at the T5-T10levels when RT-AIS patients change from the supine to the prone position. The spinal surgeon should be aware of these altered conditions to avoid injury to the aorta during pedicle screw insertion in RT-AIS patients who are in the prone position.Chapter2(section2) The differences in evaluating the potential risks of aorta injury from pedicle screw misplacement in adolescent idiopathic scoliosis:supine versus prone MRI imagesObjective:To explore the differences in evaluating the potential risks of aorta injury (TRAI) from thoracic pedicle screw (TPS) misplacement in right thoracic adolescent idiopathic scoliosis (RT-AIS) patients between the supine and prone MRI images.Methods:This prospective study included thirty-five RT-AIS patients who underwent MRI scans in both the supine and prone positions. We evaluated on the supine and prone MRI images the aorta position relative to the scoliotic spine, and simulated placement of a left TPS with a lateral deviation different from the medium trajectory using Surgimap Spine imaging software. The maximum error of lateral direction was set to10°,20°or30°(three scenarios), and the length of the TPS was set at30mm,35mm or40mm (three scenarios). We set up a total of nine patterns of lateral pedicle screw misplacement. TRAI was defined as the virtual TPS crossing the aorta, and was calculated at each level in9scenarios. The percentages of TRAI were compared in each pattern of lateral pedicle screw misplacement and each level from T5to T12. Correlation analysis was made between the percentages of TRAI and the direction errors as well as lengths of pedicle screw. Importantly, we explore differences in evaluating TRAI from TPS misplacement between the supine and prone MRI images. Results:The percentages of warning misplacement were positive correlation with the direction errors (rsupine=0.645, rprone=0.571; P＜0.01) and lengths of pedicle screw (rsupine=0.388, rprone=0.453; P<0.01). In9scenarios, with the increment of the lengths or/and direction errors of the simulated TPS, the risks of aorta impingement were constantly elevated at all the levels. The difference of TRAI was observed between the supine versus prone MRI images at each level. Based on supine MRI images, the simulated40mm TPS at T11, T12and T5posed a higher potential risk of aorta injury (51%,40%,37%, respectively) within30°lateral direction error. Based on prone MRI images, correspondly, the simulated40mm TPS at T5, T11, T6and T12posed a higher potential risk of aorta injury (71%,66%,63%,51%, respectively) within the same lateral direction error.Conclusion:Prone positioning may increase the potential risk of aorta injury in RT-AIS patients, particularly at T5-T6and T11-T12even if a left TPS just barely touches the anteriolateral or lateral cortex of the vertebrae. Laterally misplaced TPS should be removed at these high aorta-at-risk levels.Chapter3(section1) Analysis of factors associated with postoperative shoulder balance in Lenke Type1adolescent idiopathic scoliosisObjective:To study the factors associated with postoperative shoulder balance in Lenke Type1adolescent idiopathic scoliosis (AIS) patients with preoperative right-elevated shoulder after posterior thoracic fusion.Methods:A total of34Lenke Type1AIS patients were recruited between October2006to October2008. There were8boys and26girls with an average age of15.1 years (range,12-19years). Posterior thoracic fusion was performed in all the patients. There were23cases proximally fused to T4and11cases fused to T5. Pearson’s correlation analysis was made between radiographic shoulder height (RSH) at the latest follow-up and preoperative T1tilt, clavicle angle (CA), coracoids process height (CPH), apical vertebral translation (AVT), RSH, coronal and bending proximal/main thoracic curve (PT and MT) Cobb angle, curve flexibility as well as correction ratio of the MT curve.Results:All patients presented right-elevated shoulder preoperatively, with an mean RSH of (-15.9±5.8)mm. At the latest follow-up, PT curve correction was44.3%±16.3%, and MT curve correction was70.4%±9.6%. Of the34patients with an average postoperative RSH of (0.4±7.9)mm,32patients had balanced shoulders, and only2patients had mild shoulder imbalance with left-elevated shoulder. The RSH at the latest follow-up was found to be negatively correlated with PT curve flexibility (r=-0.682, P＜0.01), but positively correlated with bending PT Cobb angle (r=0.642, P<0.01) and correction ratio of the MT curve (r=0.557, P<0.01). No significant correlations were found between RSH at the latest follow-up and preoperative Tl tilt, CA, CPH, AVT, RSH, coronal PT and MT Cobb angle, bending Cobb angle as well as flexibility of MT curve (P>0.05).Conclusion:For the Lenke Type1AIS patients with preoperative right-elevated shoulder, proximal fusion to T4or T5could improve shoulder balance significantly. However, the low PT curve flexibility and overcorrection of MT curve may be associated with postoperative shoulder imbalance in such patients.Chapter3(section2) Influence of the upper fused vertebra on postoperative shoulder balance for Lenke Type1adolescent idiopathic scoliosis patientsObjective:To analyze the influence of upper fused vertebra on postoperative shoulder balance in Lenke Type1adolescent idiopathic scoliosis (AIS) patients with preoperative leveled shoulders.Methods:A total of32Lenke Type1AIS patients with preoperative leveled shoulders were included in the study. There were6boys and26girls with an average age of14.9years old (range,13-19years). Thirty-two patients who underwent posterior thoracic fusion were divided into two groups:Group A (n=19) included those who had a proximal fusion to T3; Group2(n=13) included those who had a proximal fusion to T4. Radiographic measures for shoulder balance include radiographic shoulder height (RSH), coracoids process height (CPH), and clavicle angle (CA). Radiographic measures for global balance include proximal/main thoracic (PT or MT) curve Cobb angle, apical vertebral translation (AVT) and trunk shift. Radiographic outcomes before and after surgery were compared between two groups.Results:There was no difference between the two groups in all preoperative radiographic parameters including RSH, CPH, CA, PT or MT curve Cobb angle, curve flexibility, AVT and trunk shift (all P>0.05). There were also no postoperative differences between groups in PT or MT Cobb angle, AVT and trunk shift.(all P>0.05) At the latest follow-up, RSH, CPH and CA in group A were lower than those in group B (1.2±2.1mm vs.1.6±2.5mm,2.4±3.7mm vs.2.7±3.3mm,0.7±1.6°vs.1.2±2.3°, respectively).However, these differences did not reach statistical significance (P>0.05).Conclusion:For the Lenke Type1AIS patient with leveled shoulders, proximal fusion to T4could produce equivalent correction of scoliosis and shoulder balance to proximal fusion to T3. |
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