title: Chondrocalcinosis is common in the absence of knee involvement.
abstract: BACKGROUND
  We aimed to describe the distribution of radiographic chondrocalcinosis (CC) and to examine whether metacarpophalangeal joint (MCPJ) calcification and CC at other joints occurs in the absence of knee involvement.
  
  
  METHODS
  This was a cross-sectional study embedded in the Genetics of Osteoarthritis and Lifestyle study (GOAL). All participants (n = 3,170) had radiographs of the knees, hands, and pelvis. These were scored for radiographic changes of osteoarthritis (OA), for CC at knees, hips, symphysis pubis, and wrists, and for MCPJ calcification. The prevalence of MCPJ calcification and CC overall, at each joint, and in the presence or absence of knee involvement, was calculated.
  
  
  RESULTS
  The knee was the commonest site of CC, followed by wrists, hips, and symphysis pubis. CC was more likely to be bilateral at knees and wrists but unilateral at hips. MCPJ calcification was usually bilateral, and less common than CC at knees, hips, wrists, and symphysis pubis. Unlike that previously reported, CC commonly occurred without any knee involvement; 44.4% of wrist CC, 45.9% of hip CC, 45.5% of symphysis pubis CC, and 31.3% of MCPJ calcification occurred in patients without knee CC. Those with meniscal or hyaline articular cartilage CC had comparable ages (P = 0.21), and neither preferentially associated with fibrocartilage CC at distant joints.
  
  
  CONCLUSIONS
  CC visualized on a plain radiograph commonly occurs at other joints in the absence of radiographic knee CC. Therefore, knee radiographs alone are an insufficient screening test for CC. This has significant implications for clinical practice, for epidemiologic and genetic studies of CC, and for the definition of OA patients with coexistent crystal deposition.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Abhishek
authors.forename: Sally
authors.initials: S
authors.lastname: Doherty
authors.forename: Rose
authors.initials: R
authors.lastname: Maciewicz
authors.forename: Kenneth
authors.initials: K
authors.lastname: Muir
authors.forename: Weiya
authors.initials: W
authors.lastname: Zhang
authors.forename: Michael
authors.initials: M
authors.lastname: Doherty
mesh_terms: D000368:Aged; D002805:Chondrocalcinosis / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging*; D008297:Male; D008403:Mass Screening / Q000379:methods; D008662:Metacarpophalangeal Joint / Q000000981:diagnostic imaging; D008875:Middle Aged; D010003:Osteoarthritis / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D015995:Prevalence; D011859:Radiography; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014955:Wrist Joint / Q000000981:diagnostic imaging