title: Anterior impingement test for labral lesions has high positive predictive value.
abstract: BACKGROUND
  The anterior impingement test is intended to detect anterosuperior acetabular labral lesions. In patients treated for labral lesions its sensitivity is reportedly 95% to 100%, and in a small group of patients undergoing periacetabular osteotomy, its sensitivity was 59% and specificity 100%. However, the sensitivity, specificity, positive predictive value, and negative predict value of this test to detect these labral lesions in unselected patients with hip pain are unknown.
  
  
  OBJECTIVE
  We investigated these four parameters (1) in unselected patients with hip pain, and (2) in three subgroups of patients with dysplasia, femoroacetabular impingement (FAI), and with an intact joint space.
  
  
  METHODS
  We prospectively studied 69 patients (15 men and 54 women) with a mean age of 57.2 years (range, 27-81 years). One observer performed the anterior impingement test in all patients. We determined the presence or absence of an anterosuperior labral lesion with radial MRI in 107 hips (38 patients in both hips: 14 with pain, and 24 without pain). We also investigated the parameters in the three subgroups which consisted of 60 cases of dysplasia, 27 cases of FAI, and 80 cases with intact joint space; the third subgroup partially overlapped the first and second subgroups.
  
  
  RESULTS
  The four parameters in all hips were 50.6% (45/89), 88.9% (16/18), 95.7% (45/47), and 26.7% (16/60), respectively. Parameters in the three subgroups were similar to those of all cases.
  
  
  CONCLUSIONS
  Although the sensitivity of the anterior impingement test did not reach a sufficient level for detecting anterosuperior labral lesions, we believe the high positive predictive value makes the test useful.
  
  
  METHODS
  Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.
authors: Department of Orthopedic Surgery, Kansai Rosai Hospital, 1-69 Inabasou 3 Chome, Amagasaki, Hyogo 660-8511, Japan. hana-osaka@umin.net
authors: Takehito
authors: T
authors: Hananouchi
authors: Yukihiko
authors: Y
authors: Yasui
authors: Kengo
authors: K
authors: Yamamoto
authors: Yukiyoshi
authors: Y
authors: Toritsuka
authors: Kenji
authors: K
authors: Ohzono
mesh_terms: D000077:Acetabulum / Q000002:abnormalities / Q000473:pathology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018771:Arthralgia / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D001696:Biomechanical Phenomena; D005260:Female; D057925:Femoracetabular Impingement / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D006618:Hip Dislocation, Congenital / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D006621:Hip Joint / Q000002:abnormalities / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D010808:Physical Examination; D011237:Predictive Value of Tests; D011446:Prospective Studies; D016059:Range of Motion, Articular; D012680:Sensitivity and Specificity