title: Validity and reliability of the metric measurements in the assessment of lumbar spine motion in patients with ankylosing spondylitis.
abstract: METHODS
  A prospective, controlled clinical study performed in a tertiary care center.
  
  
  OBJECTIVE
  To determine reliability and validity of low-tech measurements in assessment of range of motion (ROM) of lumbar flexion in ankylosing spondylitis (AS).
  
  
  BACKGROUND
  ROM measurements of lumbar flexion in patients with AS and healthy subjects are evaluated using original Schober test (OST), modified Schober index (MSI), and modified-modified Schober test (MMST) and compared with radiography.
  
  
  METHODS
  Fifty patients with AS and 17 healthy subjects were included. A tape measure was used for measuring OST, MSI, and MMST, and goniometer was used for measuring angle of lumbar ROM on lateral radiographical views in erect position and maximal forward bending position.
  
  
  RESULTS
  Angle between L1 and S1 vertebrae displayed a change upon flexion by 18.2° ± 18.7° in AS group and 30.4° ± 11.1° in controls (P = 0.002). Angle between L3 and S1 vertebrae was detected to change upon flexion by 25.3° ± 25.4° in AS group and 46.7° ± 14.2° in controls (P = 0.0001). A weak correlation was observed between MSI, OST, and L1-S1 radiographical mobility measurements as (P = 0.018 and P = 0.063) and MSI, OST, and L3-S1 radiographical mobility measurements as (P = 0.009 and P = 0.024), respectively for AS. There were correlations between MSI, OST, and radiographical mobility measurements in patients with AS (r = 0.333, P = 0.018, and r = 0.363, P = 0.009, respectively). There was a correlation between OST and radiographical mobility measurements in controls (r = -0.504, P = 0.039). Intrarater reliability was determined to be excellent for OST, MSI, and MMST.
  
  
  CONCLUSIONS
  Despite excellent intrarater reliabilities for OST, MSI, and MMST, only a weak correlation could be established between OST, MSI, and MMST and radiographical analysis. MMST was found not to reflect lumbar spine angular motions. Although MSI reflected spinal mobility better than OST, both seemed to reflect lumbar spine angular motion poorly.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Bezmialem Vakif University, Istanbul, Turkey. aylin_rezvani@yahoo.com
authors.forename: Aylin
authors.initials: A
authors.lastname: Rezvani
authors.forename: Onder
authors.initials: O
authors.lastname: Ergin
authors.forename: Ilhan
authors.initials: I
authors.lastname: Karacan
authors.forename: Mehmet
authors.initials: M
authors.lastname: Oncu
mesh_terms: D000328:Adult; D053587:Arthrometry, Articular / Q000295:instrumentation / Q000379:methods*; D005260:Female; D057918:Fiducial Markers; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D011187:Posture; D011859:Radiography; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D012447:Sacrum / Q000000981:diagnostic imaging / Q000503:physiopathology; D012720:Severity of Illness Index; D013167:Spondylitis, Ankylosing / Q000000981:diagnostic imaging / Q000503:physiopathology*; D055815:Young Adult