Adolescent Idiopathic Scoliosis Postoperative Spine - Pelvis Relations Discussed

ObjectivesThe purpose of the current retrospective review is to study the incidences of coronal pelvic obliquity following surgical correction of adolescent idiopathic scoliosis(AIS), and to evaluate the relation between the sagittal spine and pelvis following spinal instrumentation and fusion.Materials and MethodsMedical records and radiographs of 513 patients who underwent surgical treatment in Peking Union Medical Hospital were reviewed, and the incidence of postoperative coronal pelvic obliquity was analyzed.A cohort of 70 patients (62 females and 8 males) who have complete medical records and radiographs were recruited. Five sagittal parameters were evaluated on preoperative and postoperative standing lateral radiographs: thoracic kyphosis(TK), lumbar lordosis(LL), sacral slope (SS), pelvic tilt(PT), and pelvic incidence(PI). Pearson coefficients were used to investigate the relation between all parameters preoperatively and postoperatively.ResultsThe incidence of postoperative coronal pelvic obliquity was 2.92%, the mean draw was 7.13°±2.03°(5°-11°) .PI was a real pelvic parameter , and not significantly modified by surgery . The preoperative relation between LL and TK is significant but the postoperative relation is not significant.There are little relations between TK and pelvic parameters preoperatively and postoperatively. PI and SS were strongly correlated with LL preoperatively and postoperatively . But the relation between LL and PT was not significant postoperatively. PI was strongly related to SS and PT preoperatively and postoperatively.Conclusions1. The cause of postoperative coronal pelvic obliquity was still unclear.2. PI is recognized as a real pelvic morphological parameter, which should not be significantly modified by surgery, its preoperative evaluation could become very helpful in the determination of an perfect postoperative sagittal profile.3.The close interdependence between LL and pelvic parameters(PI,SS) preoperatively is maintained postoperatively following surgery. In the planning of surgery for AIS, it may be helpful to evaluate the sagittal pelvic parameters in addition to the spinal curves.4. There are little relations between TK and pelvic parameters preoperatively and postoperatively .The preoperative relation between LL and TK is significant but the postoperative relation is not significant. This relation must be considered in the planning of surgery for AIS.