A Retrospective Analysis Of Causes On Postoperative Distal Coronal Imbalance For Lenkel Adolescent Idiopathic Scoliosis

Objective:1. We took a retrospective study of the adolescent idiopathic scoliosis patients who underwent posterior-only approach orthopedic surgery in December2004to August2011to assess the trunk balance, speculated the reasons that made trunk imbalance.2. Proposed some preventive measures and treatments. Materials and Methods:Follow-up the idiopathic scoliosis patients who underwent posterior-only approach orthopedic surgery in December2004to August2011to assess the trunk balance. Exclude cases of pelvic tilt and L4tilt.All patients were operated by the same surgery team. All cases are divided into groups based on Risser level(X1)、Length of fusion segments(X2)、 Kind of internal fixation(X3)、The result of correction rate/Flexibility index(X4)、Flexibility index of distal curve(X5).Including taking the whole spine X-ray and imaging evaluation.Imaging evaluation:including preoperative full spine anterioposterior and lateral films, Bending films, immediately postoperative the whole spine anterioposterior and lateral films, the final follow up the whole spine anterioposterior and lateral films.Results:Totally98cases were evaluated and followed up duration from6to48monthes,mean26.14±9.34monthes.31boys and67girls, Age11-18years old,mean14.13±3.08years old.19cases(19.38%) lost balance immediately after operation. From these cases, there were14of self-correction.5were followed one and more years,1had no progress.4of5had distal levels added on, and then took Brace treatment. None of4got progress.12cases of immediate postoperative trunk balance, but follow-up, in a loss of balance.8cases had no progress.3of12had distal levels added on, then took Brace treatment. None of3got progress.1shift to reoperation. There were17cases (17.34%)had distal coronal imbalance.15of them showed subjective satisfaction with operation.2cases had low back pain, still showed satisfaction with postoperative appearance and quality of life. Logistic regression analysis shows:lower Risser level、shorter of fusion segments、hooks with screws fixation、 the result of correction rate/Flexibility index>1、poorer flexibility index of distal curve are risk factors of postoperative distal coronal imbalance of Lenkel adolescent idiopathic scoliosis.Conclusion:1.shorter of fusion segments、excessive thoracic curve correction and poorer flexibility index of distal curve are important reasons of postoperative distal coronal imbalance of Lenkel idiopathic scoliosis.2.For (Risser lever0-3) Lenkel adolescent idiopathic scoliosis, immature bone and larger growth potential are risk factors of postoperative coronal imbalance under the treatment of selective thoracic fusion.3.For(Risser lever0-3) Lenkel adolescent idiopathic scoliosis, an appropriate extension of the fusion segments to stable vertebra will help to avoid the occurrence of adding-on phenomenon and coronal imbalance.4.For(Risser lever4-5) Lenkel adolescent idiopathic scoliosis, the characteristics of the lumbar curve ought to be taken into account when choose selective thoracic fusion. An appropriate extension of the fusion segments will help to avoid the occurrence of adding-on phenomenon and coronal imbalance.5.Selective thoracic fusion with pedicle screws allowed better maintenance of thoracic correction and less postoperative coronal imbalance than that with hooks together with screws.6.As for postoperative imbalance of Lenkel AIS, how to choose a reasonable treatment should be based on subjective symptoms of patients and the type of imbalance.When the imbalance is clear and obvious in imaging performance but satisfactory in general appearance, surgeon should carefully evaluate the necessity and effect of reoperation. Brace treatment can effectively alleviate or terminate the distal coronal imbalance progress.