title: Overdiagnosing of femoroacetabular impingement: correlation between clinical presentation and computed tomography in symptomatic patients.
abstract: OBJECTIVE
  To correlate the angles between the acetabulum and the proximal femur in symptomatic patients with femoroacetabular impingement (FAI), using computed tomography (CT).
  
  
  METHODS
  We retrospectively evaluated 103 hips from 103 patients, using multislice CT to measure the acetabular age, acetabular version (in its supraequatorial portion and in its middle third), femoral neck version, cervical-diaphyseal and alpha angles and the acetabular depth. For the statistical analysis, we used the Pearson correlation coefficient.
  
  
  RESULTS
  There were inverse correlations between the following angles: (1) acetabular coverage versus alpha angle (p = 0.019); (2) acetabular version (supraequatorial) versus alpha angle (p = 0.049). For patients with femoral anteversion lower than 15 degrees: (1) acetabular version (supraequatorial) versus alpha angle (p = 0.026); (2) acetabular version (middle third) versus alpha angle (p = 0.02). For patients with acetabular version (supraequatorial) lower than 10 degrees: (1) acetabular version (supraequatorial) versus alpha angle (p = 0.004); (2) acetabular version (middle third) versus alpha angle (p = 0.009).
  
  
  CONCLUSIONS
  There was a statistically significant inverse correlation between the acetabular version and alpha angles (the smaller the acetabular anteversion angle was, the larger the alpha angle was) in symptomatic patients, thus supporting the hypothesis that FAI occurs when cam and pincer findings due to acetabular retroversion are seen simultaneously, and that the latter alone does not cause FAI, which leads to overdiagnosis in these cases.
authors.affiliation: Imperial Hospital de Caridade, Florianópolis, SC, Brazil.
authors.forename: Richard Prazeres
authors.initials: RP
authors.lastname: Canella
authors.affiliation: Clínica Imagem, Florianópolis, SC, Brazil.
authors.forename: Guilherme Pradi
authors.initials: GP
authors.lastname: Adam
authors.affiliation: Hospital Governor Celso Ramos, Florianópolis, SC, Brazil.
authors.forename: Roberto André Ulhôa
authors.initials: RA
authors.lastname: de Castillo
authors.affiliation: Imperial Hospital de Caridade, Florianópolis, SC, Brazil.
authors.forename: Daniel
authors.initials: D
authors.lastname: Codonho
authors.affiliation: Centro de Pesquisas Oncológicas (CEPON), Florianópolis, SC, Brazil.
authors.forename: Gerson Gandhi
authors.initials: GG
authors.lastname: Ganev
authors.affiliation: Imperial Hospital de Caridade, Florianópolis, SC, Brazil.
authors.forename: Luiz Fernando
authors.initials: LF
authors.lastname: de Vicenzi
keywords: Femoroacetabular impingement; Hip; X-ray computed tomography