title: Lumbar degenerative kyphosis: radiologic analysis and classifications.
abstract: METHODS
  Retrospective study of a consecutive patient series.
  
  
  OBJECTIVE
  To review the radiographic classification of patients with sagittal imbalance due to lumbar degenerative kyphosis (LDK) and to determine correlation between thoracic and lumbar curve.
  
  
  BACKGROUND
  Lumbar degenerative kyphosis is one of the common spinal deformities in Asian countries, especially Korea and Japan. However, there have been few studies regarding the classification and treatment of this disease.
  
  
  METHODS
  Seventy-eight patients with LDK were analyzed and classified according to the standing lateral whole spine findings. Total lumbar lordosis (L1-S1), thoracic kyphosis (T5-T12), sacral slope, thoracolumbar angle (T11-L1), and sagittal vertical axis (SVA) were measured on the lateral view of the whole spine. Spinal curve deformities were classified into 2 groups according to the thoracolumbar (T-L) junction angle: flat or lordotic angle (Group 1; N = 53) and kyphotic angle (Group 2; N = 25).
  
  
  RESULTS
  In Group 1, significant correlations between the thoracic and lumbar curves (r = 0.772, P < 0.0001), and between the lumbar curve and sacral slope (r = 0.785, P < 0.0001) were observed. By this result, Group 1 was classified as sagittal thoracic compensated group. In contrast, In Group 2, no correlation was found between the thoracic and lumbar curves in the decompensated group (r = 0.179, P = 0.391), but we found a significant correlation between lordosis and sacral slope (r = 0.442, P = 0.027). By this result, Group 2 was classified as sagittal thoracic decompensated group. There was significant difference in SVA between 2 groups (P = 0.020).
  
  
  CONCLUSIONS
  The angle of the thoracolumbar junction is an important parameter in determining whether a sagittal thoracic compensatory mechanism exists in LDK. We assumed that existence of a compensatory mechanism in the proximal spine is central to the determination of the fusion levels in the treatment of LDK.
authors.affiliation: Department of Neurosurgery, Gimpo Airport Wooridul Spine Hospital, Seoul, Korea. spinejjs@yahoo.co.kr
authors.forename: Jee-Soo
authors.initials: JS
authors.lastname: Jang
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Lee
authors.forename: Jun-Hong
authors.initials: JH
authors.lastname: Min
authors.forename: Kyoung-Mi
authors.initials: KM
authors.lastname: Han
mesh_terms: D000222:Adaptation, Physiological; D000368:Aged; D001696:Biomechanical Phenomena; D006801:Humans; D007738:Kyphosis / Q000145:classification* / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008141:Lordosis / Q000145:classification / Q000000981:diagnostic imaging / Q000503:physiopathology; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000502:physiology; D008875:Middle Aged; D011187:Posture; D011859:Radiography; D012189:Retrospective Studies; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000502:physiology