title: Prevalence of cam-type deformity on hip magnetic resonance imaging in young males: a cross-sectional study.
abstract: OBJECTIVE
  To determine the prevalence of cam-type deformities on hip magnetic resonance imaging (MRI) in young males.
  
  
  METHODS
  This was a population-based cross-sectional study in young asymptomatic male individuals who underwent clinical examination and completed a self-report questionnaire. A random sample of participants was invited for MRI of the hip. We graded the maximal offset at the femoral head-neck junction on radial sequences using grades from 0 to 3, where 0 = normal, 1 = possible, 2 = definite, and 3 = severe deformity. The prespecified main analyses were based on definite cam-type deformity grades 2 or 3. We estimated the prevalence of the cam-type deformity adjusted for the sampling process overall and according to the extent of internal rotation. Then we determined the location of the deformity on radial MRI sequences.
  
  
  RESULTS
  A total of 1,080 subjects were included in the study and 244 asymptomatic males with a mean age of 19.9 years attended MRI. Sixty-seven definite cam-type deformities were detected. The adjusted overall prevalence was 24% (95% confidence interval [95% CI] 19-30%). The prevalence increased with decreasing internal rotation (P < 0.001 for trend). Among those with a clinically decreased internal rotation of < 30°, the estimated prevalence was 48% (95% CI 37-59%). Sixty-one of 67 cam-type deformities were located in an anterosuperior position.
  
  
  CONCLUSIONS
  Cam-type deformities can be found on MRI in every fourth young asymptomatic male individual and in every second male with decreased internal rotation. The majority of deformities are located in an anterosuperior position.
authors.affiliation: University of Bern and Inselspital, Bern University Hospital, Bern, Switzerland. rbach@ispm.unibe.ch
authors.forename: Stephan
authors.initials: S
authors.lastname: Reichenbach
authors.forename: Peter
authors.initials: P
authors.lastname: Jüni
authors.forename: Stefan
authors.initials: S
authors.lastname: Werlen
authors.forename: Eveline
authors.initials: E
authors.lastname: Nüesch
authors.forename: Christian W
authors.initials: CW
authors.lastname: Pfirrmann
authors.forename: Sven
authors.initials: S
authors.lastname: Trelle
authors.forename: Alex
authors.initials: A
authors.lastname: Odermatt
authors.forename: Willy
authors.initials: W
authors.lastname: Hofstetter
authors.forename: Reinhold
authors.initials: R
authors.lastname: Ganz
authors.forename: Michael
authors.initials: M
authors.lastname: Leunig
mesh_terms: D000077:Acetabulum / Q000002:abnormalities* / Q000000981:diagnostic imaging; D000293:Adolescent; D001696:Biomechanical Phenomena; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005270:Femur Head / Q000002:abnormalities* / Q000000981:diagnostic imaging; D006615:Hip / Q000002:abnormalities / Q000000981:diagnostic imaging; D006621:Hip Joint / Q000002:abnormalities* / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D006801:Humans; D007592:Joint Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D011859:Radiography; D055815:Young Adult