title: In Vivo MRI Measurement of Spinal Cord Displacement in the Thoracolumbar Region of Asymptomatic Subjects with Unilateral and Sham Straight Leg Raise Tests.
abstract: BACKGROUND
  Normal displacement of the conus medullaris with unilateral and bilateral SLR has been quantified and the "principle of linear dependence" has been described.
  
  
  OBJECTIVE
  Explore whether previously recorded movements of conus medullaris with SLRs are i) primarily due to transmission of tensile forces transmitted through the neural tissues during SLR or ii) the result of reciprocal movements between vertebrae and nerves.
  
  
  METHODS
  Controlled radiologic study.
  
  
  METHODS
  Ten asymptomatic volunteers were scanned with a 1.5T magnetic resonance (MR) scanner using T2 weighted spc 3D scanning sequences and a device that permits greater ranges of SLR. Displacement of the conus medullaris during the unilateral and sham SLR was quantified reliably with a randomized procedure. Conus displacement in response to unilateral and sham SLRs was quantified and the results compared.
  
  
  RESULTS
  The conus displaced caudally in the spinal canal by 3.54±0.87 mm (mean±SD) with unilateral (p≤.001) and proximally by 0.32±1.6 mm with sham SLR (p≤.542). Pearson correlations were higher than 0.99 for both intra- and inter-observer reliability and the observed power was 1 for unilateral SLRs and 0.054 and 0.149 for left and right sham SLR respectively.
  
  
  CONCLUSIONS
  Four relevant points emerge from the presented data: i) reciprocal movements between the spinal cord and the surrounding vertebrae are likely to occur during SLR in asymptomatic subjects, ii) conus medullaris displacement in the vertebral canal with SLR is primarily due to transmission of tensile forces through the neural tissues, iii) when tensile forces are transmitted through the neural system as in the clinical SLR, the magnitude of conus medullaris displacement prevails over the amount of bone adjustment.
authors.affiliation: Kuopio University Hospital, Department of Physical and Rehabilitation Medicine, Kuopio, Finland.|Josip Juraj Strossmayer University of Osijek, Faculty of Medicine, Orthopaedic and Rehabilitation Hospital "Prim. dr.Martin Horvat", Rovinj, Croatia.
authors.forename: M
authors.initials: M
authors.lastname: Rade
authors.affiliation: Kuopio University Hospital, Department of Radiology, Kuopio, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Könönen
authors.affiliation: Kuopio University Hospital, Department of Radiology, Kuopio, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Marttila
authors.affiliation: Kuopio University Hospital, Department of Physical and Rehabilitation Medicine, Kuopio, Finland.|Neurodynamic Solutions, Adelaide, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Shacklock
authors.affiliation: Kuopio University Hospital, Department of Radiology, Kuopio, Finland.
authors.forename: R
authors.initials: R
authors.lastname: Vanninen
authors.affiliation: Tampere University Hospital, Department of Physical and Rehabilitation Medicine, Tampere, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Kankaanpää
authors.affiliation: Kuopio University Hospital, Department of Physical and Rehabilitation Medicine, Kuopio, Finland.
authors.forename: O
authors.initials: O
authors.lastname: Airaksinen
mesh_terms: D000328:Adult; D005260:Female; D006615:Hip / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D007717:Knee / Q000000981:diagnostic imaging / Q000503:physiopathology; D007866:Leg / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D009068:Movement / Q000502:physiology; D010388:Pelvis / Q000000981:diagnostic imaging / Q000503:physiopathology; D013116:Spinal Cord / Q000000981:diagnostic imaging / Q000503:physiopathology*; D013118:Spinal Cord Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology*; D013127:Spinal Nerves / Q000000981:diagnostic imaging / Q000503:physiopathology; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology