title: Lumbar Lordosis Minus Thoracic Kyphosis: A Novel Regional Predictor for Sagittal Balance in Elderly Populations.
abstract: METHODS
  A retrospective study.
  
  
  OBJECTIVE
  The aim of this study is to introduce a novel regional predictor for sagittal balance in elderly populations and explore its effectiveness of evaluating sagittal balance.
  
  
  BACKGROUND
  Sagittal balance is getting increasing recognition of importance due to its significant association of health-related quality of life. However, no regional parameters could well reflect and predict the whole sagittal balance.
  
  
  METHODS
  Medical records of elderly patients in our outpatient clinic from January 2012 to January 2014 were reviewed with standing full-spine lateral radiograph. Radiological parameters were evaluated, including max thoracic kyphosis (maxTK), max lumbar lordosis (maxLL), LL minus TK(LL-TK), PI minus LL (PI-LL), sacrum slope (SS), pelvic tilt (PT), pelvic incidence (PI), and SVA (sagittal vertical axis). Correlation analysis between SVA, LL-TK, and other radiological spinopelvic parameters and was pursued. Patients were divided into two groups according to whether patients were well-aligned in sagittal plane: Group A (well-aligned, SVA ≤50  mm) and Group B (poorly aligned, SVA >50  mm), and demographic and sagittal parameters were compared. LL-TK ≥0° and PI-LL ≤13° were used as a threshold value to evaluate their effectiveness of prediction for sagittal balance.
  
  
  RESULTS
  A total of 129 patients (M: 25 and F: 104) were included in this study. SVA was significantly correlated with NRS (numeric rating scales), age, maxLL, PT, LL-TK, and PI-LL (all, P < 0.05). Age, maxTK, maxLL, SS, PT, PI, SVA, and NRS were significantly correlated with LL-TK (all P < 0.05). Significant differences were found in age, maxLL, PT, LL-TK, PI-LL, SVA, and NRS between Group A (M: 15 and F: 72) and Group B (M: 10 and F: 32) (all P < 0.05). Furthermore, both LL-TK ≥0° and PI-LL ≤13° were observed in 75 patents, among which SVA ≤50 mm was found in 67 patients (89%). Among patients whose LL-TK and PI-LL were <0° and >13°, 34 patients were poorly aligned (34/39, 87%).
  
  
  CONCLUSIONS
  LL-TK was a good regional predictor for sagittal balance in elderly population, especially combined with PI-LL.
  
  
  METHODS
  4.
authors.affiliation: *Department of Orthopaedics †Department of Laboratory Medicine, Changhai Hospital, Second Military Medical University, People's Republic of China.
authors.forename: Changwei
authors.initials: C
authors.lastname: Yang
authors.forename: Mingyuan
authors.initials: M
authors.lastname: Yang
authors.forename: Xianzhao
authors.initials: X
authors.lastname: Wei
authors.forename: Jie
authors.initials: J
authors.lastname: Shao
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Chen
authors.forename: Jian
authors.initials: J
authors.lastname: Zhao
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Zhu
authors.forename: Dawei
authors.initials: D
authors.lastname: He
authors.forename: Ming
authors.initials: M
authors.lastname: Li
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000000981:diagnostic imaging* / Q000453:epidemiology; D008141:Lordosis / Q000000981:diagnostic imaging* / Q000453:epidemiology; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D004856:Postural Balance; D011237:Predictive Value of Tests; D011859:Radiography; D012189:Retrospective Studies; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging*