title: Computational measurement of joint space width and structural parameters in normal hips.
abstract: BACKGROUND
  Joint space width (JSW) of hip joints on radiographs in normal population may vary by related factors, but previous investigations were insufficient due to limitations of sources of radiographs, inclusion of subjects with osteoarthritis, and manual measurement techniques. We investigated influential factors on JSW using semiautomatic computational software on pelvic radiographs in asymptomatic subjects without radiological osteoarthritic findings.
  
  
  METHODS
  Global and local JSW at the medial, middle, and lateral compartments, and the hip structural parameters were measured in asymptomatic, normal 150 cases (300 hips), using a customized computational software.
  
  
  RESULTS
  Reliability of measurement in global and local JSWs was high with intraobserver reproducibility (intraclass correlation coefficient) ranging from 0.957 to 0.993 and interobserver reproducibility ranging from 0.925 to 0.985. There were significant differences among three local JSWs, with the largest JSW at the lateral compartment. Global and medial local JSWs were significantly larger in the right hip, and global, medial and middle local JSWs were significantly smaller in women. Global and local JSWs were inversely correlated with CE angle and positively correlated with horizontal distance of the head center, but not correlated with body mass index in men and women. They were positively correlated with age and inversely correlated with vertical distance of the head center only in men.
  
  
  CONCLUSIONS
  There were interindividual variations of JSW in normal population, depending on sites of the weight-bearing area, side, gender, age, and hip structural parameters. For accurate diagnosis and assessment of hip osteoarthritis, consideration of those influential factors other than degenerative change is important.
authors.affiliation: Department of Orthopaedic Medical Engineering, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. nishii@ort.med.osaka-u.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Nishii
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Shiomi
authors.forename: Takashi
authors.initials: T
authors.lastname: Sakai
authors.forename: Masaki
authors.initials: M
authors.lastname: Takao
authors.forename: Hideki
authors.initials: H
authors.lastname: Yoshikawa
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Sugano
mesh_terms: D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D015588:Observer Variation; D011859:Radiography; D012016:Reference Values; D015203:Reproducibility of Results