title: Influence of age and sagittal balance of the spine on the value of the pelvic incidence.
abstract: BACKGROUND
  The pelvic incidence (PI) was recognized as the key factor of the sagittal balance of the spine. Its value was described own for each individual and unchanged during adulthood.
  
  
  OBJECTIVE
  To bring out the effect of the age and of a sagittal imbalance in the variability of the value of PI.
  
  
  METHODS
  200 subjects with chronic low back pain due to sagittal imbalance were compared to 89 normal subjects. For each groups, the cases were divided according to the age (19-40, 6-40 years, over 60 years). The PI and the sagittal positional parameters were measured on large radiographs in standardized standing position.
  
  
  RESULTS
  The correlation between age and PI was observed significant only for the >60 years cases. The mean values of PI were significantly greater for these cases.
  
  
  CONCLUSIONS
  An increase of the value of PI was attributable to a twisting mobilization within the sacroiliac joint. It results from a forward projection of the gravity due to a sagittal disturbance and a pelvic compensatory backward rotation. This twisting into the sacroiliac joint was incriminated in the origin of chronic low back pain.
  
  
  CONCLUSIONS
  The sagittal pelvi-spinal imbalance may be incriminated in the increasing of the value of PI by a painful destabilization sacro-iliac, with leads to an increasing of the value of PI.
authors: Department of Orthopaedic Surgery, University Hospital UCL Mont-Godinne, B-5530, Yvoir, Belgium, jean.legaye@uclouvain.be.
authors: Legaye
authors: L
authors: Jean
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008141:Lordosis / Q000000981:diagnostic imaging / Q000503:physiopathology; D017116:Low Back Pain / Q000503:physiopathology; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010388:Pelvis / Q000000981:diagnostic imaging*; D011859:Radiography; D012446:Sacroiliac Joint / Q000000981:diagnostic imaging / Q000503:physiopathology; D012447:Sacrum / Q000000981:diagnostic imaging* / Q000503:physiopathology; D013131:Spine / Q000000981:diagnostic imaging* / Q000503:physiopathology; D055815:Young Adult