| Part Ⅰ Evaluation of risks of aorta impingement for right-side thoracolumbar/Iumbar scoliosis before and after posterior pedicle screw instrumentationObjective To explore the aorta movement after posterior pedicle screw instrumentation and evaluate the potential risk of the aorta injury for pedicle screw(PS)placement in right-sided thoracolumbar/Iumbar scoliosis.Methods From Feb.2009 to Feb.2013,sixteen AIS patients with a main right-sided thoracolumbar or lumbar curve,undergoing posterior pedicle screw instrumentation in our hospital,were recruited into this study.The cohort included 4 men and 12 women,with a mean age of 16.4 years(range:13-18 years),and the Cobb angles ranged from 42° to 50°(average,43.8°).They all underwent CT scans of the lower thoracic and lumbar spine before and after operation.To identify the relative positions of the aorta to vertebrae,several parameters including Aorta-vertebra angle(a),Vertebral rotation angle(b),Lefty safety distance(LSD),and Right safety distance(RSD),were measured from the CT imagines of the middle transverse planes of vertebrae from T12 to L4.We simulated placements of the PS with lengths of 35,40,and 45 mm(three scenarios)before and after operation.The aorta was considered at a potential risk of injury when the safety distance(LSD or RSD)was less than pedicle screw length.The risks of the aorta injury from T12 to L4 were calculated before and after operation.Results Before operation,the angle a increased from T12 to L4,while the angle(3 increased from T12 through L1,but deceased from L2 to L4.The longer the screw length,the larger the risk of aorta injury.Similar to preoperative one,postoperative angle a showed an increasing trend from T12 to L4.Comparing the LSD and RSD before and after operation,the only difference was noted in the LSD at T12(P=0.028).The percentages of the aorta at a potential risk of the aorta injury from PS insertion showed a similar tendency before and after operation.Conclusions Taking Aorta movement after correction into consideration,the aorta injury risks were mainly from left PS at T12 and L1 level in right-sided thoracolumbar/lumbar curves.However,the risk of aorta injury did not increase significantly,although the aorta moved due to correction.Part Ⅱ The risk of aorta impingement from pedicle screw may increase due to aorta movement during posterior instrumentation in Lenke 5C curve:a computed tomography studyObjective To investigate the aorta movement following correction surgery for patients with thoracolumbar/lumbar scoliosis,and to determine the subsequent risk of the aorta impingement for pedicle screw(PS)misplacement.Methods Thirty-six AIS patients with a main thoracolumbar or lumbar curve were included in this study.According to the direction of the main curve,the patients were divided into Group R and Group L,with Group R comprised of sixteen patients with a right-sided curve,and with Group L comprised of twenty patients with a left-sided curve.All patients underwent CT scans of the lower thoracic and lumbar spine before and after surgery.To identify the relative positions of the aorta to vertebral body,several parameters were measured from the CT imagines of the middle transverse planes of vertebrae from T11 to L4,including aorta-vertebra angle(a),vertebral rotation angle(β),lefty safety distance(LSD),and right safety distance(RSD).The risk of the aorta impingement from T11 to L4 was calculated.And intra-group comparison regarding the position of the aorta relative to vertebral body before and after correction surgery was performed accordingly.Results After surgery,the aorta moved towards vertebral body among all levels in both groups.Compared with that in Group L,the aorta in Group R was significantly closer to entry point at all levels,especially at T11.Before surgery,the aorta in Group R was at a high risk of impingement from left PS placement regardless of the diameters of the simulated screws.While in Group L,the risk of aorta impingement was mainly caused by the right placement of 45mm PS.After surgery,both groups had an increased risk of the aorta impingement from PS insertion,especially at T11.The risk of the aorta impingement from PS placement was significantly higher in Group R than that in Group L.Conclusions The risk of aorta impingement increased as the aorta shifted leftwards after correction surgery,especially in right-sided Lenke 5C curve.Thus the preoperative risk evaluation could be insufficient for clinical practice due to aorta movement following correction surgery.Surgeons should be aware of the potential risk of aorta impingement especially when placing PS in patients with right-sided curves.Part Ⅲ Halo-femoral traction following spinal release in severe and rigid scoliosis:Does longer traction duration achieve better surgical outcomes?Objective To investigate the optimal duration of Halo-femoral traction after posterior spinal release in treating severe and rigid scoliosisMethods Thirsty-four patients with severe and rigid scoliosis who underwent spinal release,halo-femoral traction and posterior correction surgery between June 2010 and December 2013 at our center were recruited in this study.According to the traction duration,patients were divided into Group 1(less than 3 weeks)and Group 2(more than 3 weeks).Group 1 was composed of 18 patients aged 22 years,5 males and 13 females,and Group 2 included 16 subjects aged 21.4 years,4 male and 12 females.The initial major curve was(121.92±14.71)°in Group 1 and(124.60±12.91)°in Group 2.The flexibility of major curve before surgery and after Halo-femoral traction was compared.The operative time,the blood loss,the blood transfusion as well as hospital stay were also compared to investigate the optimal traction duration.Results The traction duration was significantly longer in Group 2(33.5±9.6 days)than in Group 1(17.2±4.5 days)(p=0.000).No difference was found in the maximum traction weight between two groups.The flexibility of major curve was(14.1%±7.0%)before surgery,which increased to(25.7%±7.7%)after posterior osteotomy and Halo-femoral traction,showing a significant improvement by 12.0%(p<0.000)in Group 1,and increased from(13.0%±6.6%)before surgery to(25.7%±13.2%)after posterior osteotomy and Halo-femoral traction,showing an improvement of 12.0%(p<0.000)in Group 2.No significance was noted in flexibility of major curve between two groups before surgery and after posterior osteotomy and Halo-femoral traction(p=0.67,p=0.88).No significance was noted in the correction rate between Group 1(42.4%±6.6%)and Group 2(38.9%±10.3%)(p=0.290).The second-stage operative time,blood loos,blood transfusion and complication rate significantly decreased in Group 1(p=0.010;p<0.000;p=0.010;p<0.000).Conclusion For patients with severe(Cobb angle>100°)and rigid scoliosis treating with two-stage posterior surgery,less than 3 weeks of traction duration significantly improve flexibility of major curve and acquires satisfactory correction. |
