title: Defining clinically relevant values for developmental spinal stenosis: a large-scale magnetic resonance imaging study.
abstract: METHODS
  Case-control study.
  
  
  OBJECTIVE
  The aim of this study was to define clinically relevant relative and critical (absolute) magnetic resonance imaging values of lumbar spinal stenosis in a cohort of 100 surgical cases and 100 asymptomatic controls.
  
  
  BACKGROUND
  Developmental spinal stenosis is a precipitating factor in patients presenting with lumbar canal stenosis. Yet, due to a lack of agreement on definitions and methods of assessment, as well as ethnic-specific normative values, its prevalence and significance is not known.
  
  
  METHODS
  This was a case-control study comparing 100 age and sex-matched asymptomatic, volunteers with that of 100 patients who underwent surgery for spinal stenosis. All patients were of Chinese ethnicity and their details were blinded to 2 observers. Spinal stenosis parameters were measured on the basis of axial (pedicle level) and sagittal (midsagittal) magnetic resonance images.
  
  
  RESULTS
  Anteroposterior spinal canal diameters change with levels. At each level, patients were found to have significantly narrower anteroposterior canal diameters than controls. By use of receiver operating characteristic curve, we defined developmental spinal stenosis if the anteroposterior canal diameter was at L1 <20 mm, L2 <19 mm, L3 <19 mm, L4 <17 mm, L5 <16 mm, and at S1 <16 mm on the basis of a value including 50% of controls and demonstrated best sensitivity and specificity. Furthermore, for L4, L5, and S1, critical stenosis values could be defined, below which almost all subjects needed surgery, these were L4 <14 mm, L5 <14 mm, and S1 <12 mm.
  
  
  CONCLUSIONS
  This is the largest magnetic resonance imaging-based study with standardized measurements and comparable groups to determine clinically relevant magnetic resonance imaging criteria for lumbar spinal stenosis. The findings strongly suggest that developmental stenosis plays an important role in the pathogenesis of symptomatic spinal stenosis. Critical values of stenosis below which symptoms were highly likely were defined. These will need to be validated by longitudinal studies in future. However, they may possess clinical utility in determining the appropriate levels requiring canal-widening surgery.
  
  
  METHODS
  3.
authors.affiliation: *Department of Orthopaedics & Traumatology, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China; and †Department of Orthopaedics Surgery, Nara Medical University, Kahihara, Nara, Japan.
authors.forename: Jason Pui-Yin
authors.initials: JP
authors.lastname: Cheung
authors.forename: Dino
authors.initials: D
authors.lastname: Samartzis
authors.forename: Hideki
authors.initials: H
authors.lastname: Shigematsu
authors.forename: Kenneth Man-Chee
authors.initials: KM
authors.lastname: Cheung
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D015203:Reproducibility of Results; D012447:Sacrum / Q000473:pathology; D012720:Severity of Illness Index; D013130:Spinal Stenosis / Q000473:pathology*; D013904:Thoracic Vertebrae / Q000473:pathology; D055815:Young Adult