title: Predictable correction of the unfused lumbar lordosis after thoracic correction and fusion in Scheuermann kyphosis.
abstract: METHODS
  A retrospective examination of preoperative and postoperative radiographs of the sagittal spine of 30 patients with Scheuermann kyphosis.
  
  
  OBJECTIVE
  To determine significant correlations between kyphosis and lordosis in Scheuermann kyphosis, determine predictability of spontaneous sagittal lordosis correction after thoracic correction and fusion, and understand better the biomechanics of the spine.
  
  
  BACKGROUND
  Previous studies described relations between kyphosis and lordosis in healthy people. To our knowledge, no relationships, have been described between kyphosis and lordosis in Scheuermann kyphosis.
  
  
  METHODS
  On radiographs, maximum kyphosis, maximum lordosis, sacral slope and L5-S1 angle were measured in the preoperative and postoperative standing lateral radiographs of the spine, and correlations were calculated.
  
  
  RESULTS
  Preoperative significant correlations were present between kyphosis and lordosis (R = 0.421; P = 0.021), and between lordosis and sacral slope (R = 0.824; P < 0001). Postoperative correlations were stronger (R = 0.591; P = 0.001 and R = 0.844; P < 0.001). The percentage of correction of kyphosis was correlated with the percentage of spontaneous decrease of lordosis (R = 0.593; P < 0.001). A negative correlation between L5-S1 angle and upper lumbar segment of lordosis was found before and after surgery.
  
  
  CONCLUSIONS
  This study shows a significant correlation between kyphosis and lordosis before and after surgery. Surgical correction of thoracic hyperkyphosis gives a predictable spontaneous decrease of lumbar lordosis. Correction of lordosis occurs mainly in the upper segment of lumbar lordosis.
authors: Department of Orthopedic Surgery, University Hospital Maastricht, Maastricht, The Netherlands.
authors: Rob C
authors: RC
authors: Jansen
authors: Lodewijk W
authors: LW
authors: van Rhijn
authors: André
authors: A
authors: van Ooij