title: Changes in the iliac crest-lumbar relationship from standing to prone.
abstract: BACKGROUND
  It is known that positioning patients on the Jackson and Andrews operative tables causes changes in lumbar lordosis and pelvic rotation. However, it is unknown if the relationship between the iliac crest and underlying lumbar levels, in particular the L4-L5 interspace, changes from standing to prone on these tables.
  
  
  OBJECTIVE
  To assess the changes in the relationship between the iliac crests and lumbar spinal levels from standing to prone on two different operative positions using the Jackson and Andrews frames.
  
  
  METHODS
  Comparative analysis of iliac crest position relative to spinal levels in the preoperative standing position and while positioned on the Jackson and Andrews frames.
  
  
  METHODS
  48 randomly selected patients who underwent spinal surgery on either the Jackson or Andrews frame.
  
  
  METHODS
  Imaging.
  
  
  METHODS
  Comparative measurements were made of the preoperative and intraoperative plain lateral lumbar radiographs. The location of the superior border of the iliac crest relative to the L4 lumbar spine level was compared between radiographs.
  
  
  RESULTS
  Preoperatively, the iliac crest aligned with L4/L4-L5 spinal level in 79.2% of the 48 patients compared with 85.5% of intraoperative cases (p=.59). Intraoperative iliac crest level aligned with the L4/L4-L5 level in 80.8% and 90.9% of the patients on the Andrews and Jackson tables respectively (p=.43). Thirty-four patients (70.8%) demonstrated no change in iliac crest alignment between intraoperative and preoperative radiographs. There was a trend for the iliac crest to shift cephalad with operative positioning.
  
  
  CONCLUSIONS
  Approximately 30% of patients demonstrated changes in the relationship between the iliac crest and lumbar levels between standing and positioning prone. The intraoperative position of the iliac crest aligned more accurately with the L4/L4-L5 spine level on the Jackson and Andrews frame compared with preoperative standing radiographs respectively. Further biomechanical studies should investigate the implication for lumbopelvic fixation.
authors.affiliation: Division of Spine Surgery, Department of Orthopaedics, University of Pennsylvania School of Medicine, 3400 Spruce Street, Philadelphia, 19104, USA. kingsleychin@hotmail.com
authors.forename: Kingsley R
authors.initials: KR
authors.lastname: Chin
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Kuntz
authors.forename: Henry H
authors.initials: HH
authors.lastname: Bohlman
authors.forename: Sanford E
authors.initials: SE
authors.lastname: Emery
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004867:Equipment Design; D005260:Female; D006801:Humans; D007085:Ilium / Q000000981:diagnostic imaging / Q000502:physiology* / Q000601:surgery; D007430:Intraoperative Care; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000502:physiology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care; D016684:Prone Position / Q000502:physiology*; D011859:Radiography; D013131:Spine / Q000601:surgery*; D013523:Surgical Equipment; D013514:Surgical Procedures, Operative / Q000379:methods*