| PART ⅠCoronal decompensation after hemivertebra resection in patients with congenital scoliosisObjective:In some patients who underwent posterior-only surgery,coronal decompensation may occur postoperatively during the follow-up.However,a few of valid data involving this complication in very young patients with thoracolumbar hemivertebra(HV).The objective of this study is to investigated the incidence and risk factors of coronal decompensation in patients younger than 5 years old after posterior HV resection and short fusion.Methods:A total of 179 consecutive series of patients(younger than 5 years old)who had undergone posterior-only hemivertebra resection and short fusion from February 2006 to March 2015 were reviewed.The mea age was 38±11 months(range,20-59 months),and the mean follow-up period was 41±11 months(range,24-67 months).The minimum follow-up was 24 months.Anteroposterior X-ray radiographs were obtained preoperatively and postoperatively as well as during the follow-up.Parameters were obtained on the coronal plane and the sagittal plane.Parameters on the coronal plane included the main curve,preoperative and postoperative compensated curve,lowest instrumented vertebra tilt(LIV tilt),lowest instrumented vertebra disc angle(LIV disc angle).upmost instrumented vertebra tilt(UIV tilt),upmost instrumented vertebra disc angle(UIV disc angle),LIV translation,UIV translation and coronal balance.Parameters on the sagittal plane included segmental kyphosis,proximal junctional angle and sagittal vertical axis.Patients were divided into two groups according to the behavior of the coronal compensation:Group P(progressed,curve decompensated more than twenty degrees)and Group NP(non-progressed,well compensated curve).Independent sample t tests were used to compare demographic data,radiographic outcomes before and after surgery as well as at the latest follow-up between the two groups.Results:Coronal decompensation was found in 18 patients and they were assigned to the Group P.The remaining 161 were then constituted the Group NP.The preoperative LIV translation in Group P was significantly higher than Group NP(8.5mm±6.4mm vs.10.5mm±4.9mm,P<0.01).similarly,the postoperative LIV disc angle in Group P was also significantly higher than Group NP(7.0°±3.1°比 3.1°±3.3°,P<0.01).During the follow-up period,the LIV translation and LIV disc angle in Group P experienced continuous aggravation until the initiation of brace treatment.Receiver operating characteristic curve analysis revealed that the preoperative LIV translation≥15.1mm and postoperative LIV disc angle≥5.5°were two independent risk factors for coronal decompensation.Conclusions:The incidence of the coronal decompensation is approximately 10%for young patients who accepted the posterior-only thoracolumbar hemivertebra resection and short fusion.The independent risk factors for postoperative coronal decompensation including preoperative LIV translation(≥15.1mm)and postoperative LIV disc angle(≥5.5°)should on all accounts be carefully evaluated.PART ⅡAnatomic research of one new internal fixation on pelvisObjective:The optimal technique of spino-pelvic fixation is still being developed and redefined.However,neither the valid anatomic parameters nor the potential involvement of spinal canal for one new internal fixation on pelvis have been clearly analyzed.The aim of this study is to investigate the safety and accessibility of this new placement in normal adult pelvis by three-dimensional computed tomography(3D-CT)reconstruction.Methods:A total of 60 adults with normal pelvis were reviewed retrospectively in this study.The mean age was 41.5±10.9 years(range,22-64).Based on 3D-CT reconstruction of each pelvis,simulation of inserting the iliosacral screw and the connector was performed.And the virtual channels were identified in either side of each pelvis,the trajectory of which was characterized with the optimal width and length of the bone marrow cavity.The virtual channels that holding the greatest width and length of osseous channel was measured by rotating the 3D pelvis.Parameters of the determined channel on either side included iliosacral-screw-related and connector-related ones.The former parameters included convergent angle,caudal angle,length of iliac channel,length of sacral channel,max-length of the screw and skin distance.The later parameters included divergent angle,cephalad angle,width of the S1 pedicle,depth of insertion and skin distance.Results:There was a virtual channel going through the ilium as well as the iliosacral joint and into the sacral in each side of every pelvis.The iliosacral-screw-related parameters in males including convergent angle,caudal angle,length of iliac channel,length of sacral channel,max-length of the screw and skin distance were 61.4°±5.8°,16.5°±3.1°,(16.7±2.8)mm,(73.7±5.5)mm,(97.1±5.7)mm,(65.4±11.4)mm,respectively.In females,they were 62.2°±5.5°,16.4°±3.7°,(14.8±2.6)mm,(74.4±6.5)mm,(96.2±6.2)mm,(67.8±11.1)mm,respectively.The length of iliac channel in males was higher than that of the females.The connector-related parameters in males including divergent angle,cephalad angle,width of the S1 pedicle,depth of insertion and skin distance were 28.6°±5.9°,28.2°±5.8°,(19.1±2.7)mm,(23.3±2.3)mm and(51.7±7.6)mm,respectively.In females,they were 27.8°±5.8°,26.7°±6.1°,(15.9±2.8)mm,(20.6±2.5)mm and(57.2±8.1)mm,respectively.The width of the S1 pedicle and depth of insertion in males were higher than that of the females,while the skin distance in females was higher than that of the malesConclusions:It is safe and feasible to use this new internal fixation on pelvis.Preoperative 3D-CT reconstructions may help to determine the starting point of the connector and the precise directions of the screws individually. |
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