The Research And Clinical Significance Of Sagittal Spino-pelvic Parameters Of Adolescent Idiopathic Scoliosis

Objectives:A retrospective radiographical study investigated the relationship of pelvic and spinal sagittal parameters of AIS(adolescent idiopathic scoliosis).The orthopaedic preliminary judgmentin preoperative evaluation of AIS was acquired to provide some reference basis for surgeons.Methods:39 patients with AIS undergoing posterior pedicle screw instrumentation and fusion were studied retrospectively from July 2011 to July 2014 according to the research content and inclusion criteria.Part one:the change and clinical significance of sagittal spino-pelvic parameters of AIS.There were 39 patients,13 males and 26 females in this study.Part two: the change and clinical significance of cervical spine sagittal slignment of AIS.There were 35 patients,12 males and 23 females in this study.Part three:analysis of sagittal PI minus LL in idiopathic thoracic scoliosis.There were 34 patients,13 males and 21 females in this study.All data about sagittal profile changes were analszed.The relations between spinal-pelvic parameters in the subgroup pre-operation and post-operation were determined via correlation coefficient.Results:1.Part one:PI was strongly related to SS and LL(r>0.5)preoperatively and postoperatively.PI has a moderate relationship on preoperative PT(0.3<r<0.5),but postoperatively this relationship is strong(r>0.5).How ever,there is no significant relationship between TK and the other spino-pelvic parameters preoperatively and postoperatively.Patients were separated into hypokyphosis group(n = 21)and normokyphosis group(n = 16)according to TK(TK<20°,20°<TK<40°).We observed statistically significant changes on TK,PI,SS,PT in the hypokyphosis group.But i n the normokyphosis group,only the changes of PI,PT have statistically significance.We observed a significant increasing amount of PT in the whole group and subgroups.The parameters of LL,LL within fusion,LL below fusion were no significant changes in the subgroup according to the level of LIV(lowest instrumented vertebra)postoperatively.2.Part two: The patients were subdivided in kyphosis(CL>0°)and lordosis(CL<0°)group based on CL before operation.There were 17 AIS in lordosis group,18 in kyphosis group before operation;after operation the kyphosis group subdivision in lordosis restored(group A),kyphosis decreased(group B),and lordosis increased(group C)in lordosis group the after operation.Cervical lordosis had strongly correlation with T1 slope,C2 slope(|r|>0.5,P<0.001)preoperatively and postoperatively,but moderate correlation with TK(0.3<|r|<0.5,P<0.05).No correlation was found between CL and PI?C7 SVA had moderate correlation with CL only before operation(0.3 < |r| < 0.5,P < 0.05),but nothingwas found post-operation?Significant changes on cervical decreased kyphosis were found in the kyphosis group whose TK smaller than the lordosis group before operation,accompanied with the increased T1 slope and decreased C2 slope after operation.In the kyphosis group,there was a significant decrease of cervical kyphosis coupled to an increase of TK post-op,while others cervical sagittal alignment from kyphosis to lordosis,accompanied with a decrease of LL and C7 SVA.3.Part three:Based on PI-LL before operation subdivision in mismatched(PI-LL<-10°,n=15),matched(PI-LL=-10°~0°,n=13),and the others(PI-LL>0°,n=6),the data of former two groups about sagittal profile changes were analyzed.Significant changes were found in the mismatched group whose LL larger than the ideal predicted LL,accompanied with the decreased LL,SS and pelvic retroversion after operation.The grade of P I-LL had better improved,or restored the suitable LL.In the matched group,there w ere no statistically significant changes about PT and SS.The two groups ha d normal mean PT and SVA before and after surgery.Six cases had PI-LL mismatched in the mismatched group after operation,which had a larger proportion than the matched group(P=0.018).Conclusions:1.(1)PI has a predominant role in the determination of the magnitude of LL before or after surgery.(2)Surgery on TK and/or LL activates a series of compensatory mechanisms in the pelvis(pelvic retroversion),the primary goal of which is to maintain the balance of the spine and pelvic.(3)Preoperative evaluation in AIS could become very important in the determination of the optimal LL within fusion and LL below fusion.2.(1)Cervical sagittal alignment has an important role in the balance of the spine and pelvic.(2)A reduction in thoracic kyphosis may predispose to cervical spine decompensation into kyphotic alignment.(3)Attention to properly maintaining or restoring cervical sagittal lordosis alignment should be considered in preoperative evaluation of AIS.3.(1)Pelvic retroversion is an important compensatory mechanism in the balance of the spine and pelvic.(2)Attention to properly maintaining or restoring optimal LL should be considered in preoperative evaluation of AIS,especially for the patients whose LL mismatched with PI before operation.