title: Evaluation of Cam-type femoroacetabular impingement by ultrasound.
abstract: OBJECTIVE
  In the diagnosis of femoroacetabular impingement (FAI), magnetic resonance imaging (MRI) and X-ray are widely accepted methods for detection. When evaluating the hip head-neck junction using MRI, oblique axial sequences are required. However, the construction and analysis of these images are restricted to specialist radiologists and surgeons in the field of hip joint MRI. This study sought to investigate whether ultrasound, a simple and inexpensive method, can be used as a reliable tool for diagnosing Cam-type FAI.
  
  
  METHODS
  Forty patients, with a mean age of 39 years (range, 18-61 years), were consecutively included in this prospective study, following a diagnosis of Cam-type FAI on an oblique axial MRI. All patients underwent ultrasound examination in the ventral longitudinal section at 20° external rotation, neutral position and 20° internal rotation. The alpha angle, anterior offset, offset-ratio, and anterior femoral distance (AFD) were measured using MRI and ultrasound.
  
  
  RESULTS
  No significant differences were detected between the alpha angle on MRI and that using ultrasound in the neutral position or in 20° internal rotation, with strong correlations observed between these parameters (r = 0.67 for neutral position, r = 0.77 for 20° internal rotation). The Pearson's correlation coefficient for the alpha angle on MRI and the ratio of AFD/anterior offset on ultrasound in internal rotation was 0.76 (p < 0.0001).
  
  
  CONCLUSIONS
  The results show strong correlations between MRI and ultrasound measurements in patients with Cam-type FAI. Consequently, ultrasound may provide a useful tool for the early diagnosis of Cam-type FAI in daily practice.
authors: Clinic for Orthopaedics / Traumatology / Sports Medicine, Klinikum Agnes Karll Laatzen / Klinikum Region Hannover, Hildesheimer Str. 158, 30880, Laatzen, Germany. solveig.lerch@krh.eu
authors: Solveig
authors: S
authors: Lerch
authors: Andreas
authors: A
authors: Kasperczyk
authors: Janne
authors: J
authors: Warnecke
authors: Thomas
authors: T
authors: Berndt
authors: Oliver
authors: O
authors: Rühmann
mesh_terms: D000293:Adolescent; D000328:Adult; D001182:Arthroscopy; D057925:Femoracetabular Impingement / Q000175:diagnosis* / Q000000981:diagnostic imaging; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D014463:Ultrasonography / Q000379:methods*; D055815:Young Adult