title: Retrolisthesis as a compensatory mechanism in degenerative lumbar spine.
abstract: OBJECTIVE
  Posterior vertebral translation as a type of spondylolisthesis, retrolisthesis is observed commonly in patients with degenerative spinal problems. Nevertheless, there is insufficient literature on retrolisthesis compared to anterolisthesis. The purpose of this study is to clarify the clinical features of retrolisthesis, and its developmental mechanism associated with a compensatory role in sagittal imbalance of the lumbar spine.
  
  
  METHODS
  From 2003 to 2012, 230 Korean patients who underwent spinal surgery in our department under the impression of degenerative lumbar spinal disease were enrolled. All participants were divided into four groups : 35 patients with retrolisthesis (group R), 32 patients with simultaneous retrolisthesis and anterolisthesis (group R+A), 76 patients with anterolisthesis (group A), and 87 patients with non-translation (group N). The clinical features and the sagittal parameters related to retrolisthesis were retrospectively analyzed based on the patients' medical records.
  
  
  RESULTS
  There were different clinical features and developmental mechanisms between retrolisthesis and anterolisthesis. The location of retrolisthesis was affected by the presence of simultaneous anterolisthesis, even though it predominantly manifest in L3. The relative lower pelvic incidence, pelvic tilt, and lumbar lordosis compared to anterolisthesis were related to the generation of retrolisthesis, with the opposite observations of patients with anterolisthesis.
  
  
  CONCLUSIONS
  Retrolisthesis acts as a compensatory mechanism for moving the gravity axis posteriorly for sagittal imbalance in the lumbar spine under low pelvic incidence and insufficient intra-spinal compensation.
authors: Department of Neurosurgery, Yeungnam University College of Medicine, Daegu, Korea.
authors: Ikchan
authors: I
authors: Jeon
authors: Department of Neurosurgery, Yeungnam University College of Medicine, Daegu, Korea.
authors: Sang Woo
authors: SW
authors: Kim
keywords: Lumbar spine; Retrolisthesis; Sagittal imbalance; Spondylolisthesis