title: Ultrasonographic measurements of joint cartilage thickness in healthy children: age- and sex-related standard reference values.
abstract: OBJECTIVE
  Loss of joint cartilage may be an early feature of chronic inflammatory joint diseases like juvenile idiopathic arthritis (JIA). Conventional radiography usually detects only late changes such as joint space narrowing and bone erosion rather than early inflammatory changes. Joint cartilage is easily visualized with high-frequency ultrasonography (US), but age- and gender-related normal standard reference values should be established before US measurement of cartilage thickness becomes standard procedure in the clinic.
  
  
  METHODS
  A cross-sectional study of bilateral grey-scale US cartilage thickness of the knee, ankle, wrist, and second metacarpophalangeal (MCP) and second proximal interphalangeal (PIP) joints was performed in 394 (215 boys/179 girls) healthy Danish Caucasian children aged between 7 and 16 years.
  
  
  RESULTS
  Cartilage thickness differed significantly between sexes (p < 0.001 for all joints), boys having thicker cartilage than girls. Cartilage thickness clearly decreased with increasing age in both sexes. A formula for calculating sex-specific cartilage thickness at different ages in childhood is suggested. No difference between the right and left side of the investigated joints was observed.
  
  
  CONCLUSIONS
  Using US, we established age- and sex-related normal reference intervals for cartilage thickness of the knee, ankle, wrist, and MCP and PIP joints in 7- to 16-year-old children, and designed a formula for calculating hyaline cartilage thickness in all age groups throughout childhood.
authors.affiliation: Department of Pediatrics, Aarhus University Hospital Skejby, Aarhus N, Denmark. spannow@ki.au.dk
authors.forename: Anne Helene
authors.initials: AH
authors.lastname: Spannow
authors.forename: Mogens
authors.initials: M
authors.lastname: Pfeiffer-Jensen
authors.forename: Niels T
authors.initials: NT
authors.lastname: Andersen
authors.forename: Troels
authors.initials: T
authors.lastname: Herlin
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Stenbøg
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002358:Cartilage, Articular / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D002648:Child; D003430:Cross-Sectional Studies; D003718:Denmark; D005260:Female; D006801:Humans; D007596:Joints / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D008297:Male; D012016:Reference Values; D014463:Ultrasonography