title: The prevalence of femoroacetabular impingement in radiographs of asymptomatic subjects: a cross-sectional study.
abstract: BACKGROUND
  There is a lack of uniformity in the diagnostic criteria for femoroacetabular impingement (FAI), and few studies discuss the prevalence of radiographic changes in asymptomatic individuals. These factors make it difficult to establish a natural history of this disease. The aim of this study was to assess the prevalence of radiographic signs of CAM and Pincer FAI in an asymptomatic population.
  
  
  METHODS
  A cross-sectional study was performed from July 2013 to December 2013. A total of 185 subjects were analysed.
  
  
  METHODS
  no history of hip pain or orthopedic disease; and being 20-60 years old.
  
  
  METHODS
  athletically active; or patients who would not allow acquisition of appropriate radiographs for analysis. Radiographs were obtained in anteroposterior and Dünn 45° view to access: alpha angle (AA), triangular index (TI), crossover sign (CS), lateral-centre edge (LCE) angle and acetabular index (AI).
  
  
  RESULTS
  Median age was 34 years (27-49.5) and FAI was present in 53% of all subjects. 32.44% (60) was the overall CAM-type prevalence and 42.7% (79) the overall Pincer-type prevalence. Only 2 subjects presented the 3 overcoverage signs (AI, LCE and CS). An association was noted between the presence of AI &lt;0° and the LCE &gt;40° (p = 0.05).
  
  
  CONCLUSIONS
  Our study established a higher prevalence of radiographic markers of FAI in an asymptomatic population.
authors.affiliation: 2 Department of Orthopaedics, Hospital de Clínicas de Porto Alegre (HCPA), Porto Alegre, Rio Grande do Sul - Brazil.
authors.forename: Cristiano Valter
authors.initials: CV
authors.lastname: Diesel
authors.forename: Tiango Aguiar
authors.initials: TA
authors.lastname: Ribeiro
authors.forename: Rodrigo Benedet
authors.initials: RB
authors.lastname: Scheidt
authors.forename: Carlos Alberto de Souza
authors.initials: CA
authors.lastname: Macedo
authors.forename: Carlos Roberto
authors.initials: CR
authors.lastname: Galia
mesh_terms: D000328:Adult; D001938:Brazil / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D057925:Femoracetabular Impingement / Q000000981:diagnostic imaging / Q000453:epidemiology*; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011859:Radiography; D012189:Retrospective Studies; D055815:Young Adult