title: Analysis of spinopelvic sagittal alignment in patients with thoracic and thoracolumbar angular kyphosis.
abstract: METHODS
  Retrospective and radiological analysis of spinopelvic sagittal alignment in Chinese patients with thoracic and thoracolumbar kyphosis.
  
  
  OBJECTIVE
  To determine the impact of thoracic and thoracolumbar kyphosis on pelvic sagittal morphology and the mechanisms of adjusting trunk sagittal balance.
  
  
  BACKGROUND
  Previous studies have reported the normative values of pelvic sagittal parameters and classification of normal patterns of sagittal curvature, but no study has analyzed the impact of thoracic and thoracolumbar kyphosis on pelvic sagittal morphology and the mechanisms of maintaining the sagittal balance.
  
  
  METHODS
  Whole spine and standing lateral radiographs of 49 Chinese patients with thoracic and thoracolumbar kyphosis were obtained before surgery, immediately after surgery, and in the final follow-up. The pelvic and spinal parameters were measured and the correlations of all parameters were analyzed. A descriptive analysis characterizing these parameters and a multivariate analysis were performed.
  
  
  RESULTS
  The patients had a mean age of 30.3 years, whereas the mean age at which the patients who developed kyphosis was 7.1 years. Preoperative pelvic incidence was significantly less than that of normal subjects, and there was no difference in the preoperative, in the immediate postoperative, and in the final follow-up radiographs. The magnitude of kyphosis and the levels involved were independent factors of pelvic incidence. Pelvis anteversion and lumbar hyperlordosis were the mechanisms of adjusting the trunk sagittal balance. Although kyphosis and sagittal imbalance was corrected by surgery, pelvic sagittal morphology remained unchanged.
  
  
  CONCLUSIONS
  Thoracic and thoracolumbar angular kyphosis occurring during the growth period will lead to abnormal pelvic morphology. The greater the kyphotic angle and lower the kyphotic levels, the greater the impact on the pelvic morphology during skeletal maturation. The mechanisms of adjusting the trunk sagittal balance not only include pelvis anteverting, but also lumbar hyperlordosis. The latter serves as the main mechanism once skeletal maturation has been established. After skeletal maturation, surgery can re-establish the spinal sagittal balance but not the pelvis morphology.
  
  
  METHODS
  3.
authors.affiliation: Orthopaedic Department of Peking University Third Hospital, No. 49 North Garden St., Beijing, China.
authors.forename: Weishi
authors.initials: W
authors.lastname: Li
authors.forename: Zhuoran
authors.initials: Z
authors.lastname: Sun
authors.forename: Zhaoqing
authors.initials: Z
authors.lastname: Guo
authors.forename: Qiang
authors.initials: Q
authors.lastname: Qi
authors.forename: Sang Do
authors.initials: SD
authors.lastname: Kim
authors.forename: Yan
authors.initials: Y
authors.lastname: Zeng
authors.forename: Chuiguo
authors.initials: C
authors.lastname: Sun
authors.forename: Zhongqiang
authors.initials: Z
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007738:Kyphosis / Q000000981:diagnostic imaging / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods; D010388:Pelvis / Q000000981:diagnostic imaging*; D011184:Postoperative Period; D057234:Preoperative Period; D011859:Radiography / Q000379:methods; D012189:Retrospective Studies; D013131:Spine / Q000000981:diagnostic imaging*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D055815:Young Adult