title: Effect of lumbar angular motion on central canal diameter: positional MRI study in 491 cases.
abstract: BACKGROUND
  Lumbar spinal stenosis is a common problem that is receiving attention with the advent of novel treatment procedures. Prior positional MRI studies demonstrated lumbar canal diameter changes with flexion and extension. There have not been any studies to examine the amount of spinal canal diameter change relative to the amount of angular motion. The purpose of this study was to evaluate the correlation between the lumbar canal diameter change and the angular motion quantitatively.
  
  
  METHODS
  Positional MRI (pMRI) images for 491 patients, including 310 males and 181 females (16 years-85 years of age), were obtained with the subjects in sitting flexion 40 degree, upright, and with extension of 10 degrees within a 0.6 T Positional MRI scanner. Quantitative measurements of the canal diameter and segmental angle of each level in the sagittal midline plane were obtained for each position. Then the diameter change and angular motion were examined for correlation during flexion and extension with linear regression analysis.
  
  
  RESULTS
  The lumbar segmental angles were lordotic in all positions except L1-2 in flexion. The changes of canal diameters were statistically correlated with the segmental angular motions during flexion and extension (P < 0.001). The amount of canal diameter change correlated with the amount of angular change and was expressed as a ratio.
  
  
  CONCLUSIONS
  Positional MRI demonstrated the amount of spinal canal diameter change that was statistically correlated with the segmental angular motion of the spine during flexion and extension. These results may be used to predict the extent of canal diameter change when interspinous devices or positional changes are used to treat spinal stenosis and the amount of increased canal space may be predicted with the amount of angular or positional change of the spine. This may correlate with symptomatic relief and allow for improved success in the treatment of spinal stenosis.
authors.affiliation: Department of Orthopaedic, Peking University Third Hospital, Beijing 100191, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Wei
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Wang
authors.forename: Jun
authors.initials: J
authors.lastname: Zou
authors.forename: Soon-woo
authors.initials: SW
authors.lastname: Hong
authors.forename: Haihong
authors.initials: H
authors.lastname: Zhang
authors.forename: Wubing
authors.initials: W
authors.lastname: He
authors.forename: Masashi
authors.initials: M
authors.lastname: Miyazaki
authors.forename: Sang-hun
authors.initials: SH
authors.lastname: Lee
authors.forename: Ahmet
authors.initials: A
authors.lastname: Alanay
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000033:anatomy & histology* / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology; D013115:Spinal Canal / Q000033:anatomy & histology* / Q000502:physiology; D055815:Young Adult