title: Sagittal sacropelvic morphology and balance in patients with sacroiliac joint pain following lumbar fusion surgery.
abstract: OBJECTIVE
  To investigate the sagittal sacropelvic morphology and balance of the patients with SIJ pain following lumbar fusion.
  
  
  METHODS
  Among 452 patients who underwent posterior lumbar interbody fusion between June 2009 and January 2013, patients with postoperative SIJ pain, being responded to SIJ block were enrolled. For a control group, patients matched for sex, age group, the number of fused level and fusion to sacrum were randomly selected. Patients were assessed radiologic parameters including lumbar lordosis, pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS). To evaluate the sagittal sacropelvic morphology and balance, the ratio of PT/PI, SS/PI and PT/SS were analyzed.
  
  
  RESULTS
  A total of 28 patients with SIJ pain and 56 patients without SIJ pain were assessed. Postoperatively, SIJ pain group showed significantly greater PT (p=0.02) than non-SIJ pain group. Postoperatively, PT/PI and SS/PI in SIJ pain group was significantly greater and smaller than those in non-SIJ pain group respectively (p=0.03, 0.02, respectively) except for PT/SS (p=0.05). SIJ pain group did not show significant postoperative changes of PT/PI and SS/PI (p=0.09 and 0.08, respectively) while non-SIJ pain group showed significantly decrease of PT/PI (p=0.00) and increase of SS/PI (p=0.00).
  
  
  CONCLUSIONS
  This study presents different sagittal sacropelvic morphology and balance between the patients with/without SIJ pain following lumbar fusion surgery. The patients with SIJ pain showed retroversed pelvis and vertical sacrum while the patients without SIJ pain have similar morphologic features with asymptomatic populations in the literature.
authors.affiliation: Department of Neurosurgery, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea.
authors.forename: Dong-Young
authors.initials: DY
authors.lastname: Cho
authors.forename: Myung-Hoon
authors.initials: MH
authors.lastname: Shin
authors.forename: Jung-Woo
authors.initials: JW
authors.lastname: Hur
authors.forename: Kyeong-Sik
authors.initials: KS
authors.lastname: Ryu
authors.forename: Chun-Kun
authors.initials: CK
authors.lastname: Park
keywords: Lumbar fusion surgery; Lumbopelvic parameters; Sacroiliac joint pain; Sacropelvic morphology