The Reliability and Validity of Clinical Tests Used to Assess Individuals with Potential Labral Tears of the Hip (SS-20)

Abstract

The purpose of this study was to determine the reproducibility and diagnostic accuracy of clinical tests used to examine individuals with potential labral tears of the hip. Specifically, the inter-tester reliability of the FABER, flexion-internal rotation impingement, and log roll tests as well as an assessment for greater trochanteric tenderness was examined. The diagnostic accuracy of the FABER, flexion-internal rotation impingement, flexion-external rotation tests in identifying individuals with a labral tear was also examined. We hypothesized that the four clinical tests would demonstrate moderate agreement (kappa coefficient >.40) in inter-tester reliability assessment. Additionally, we was hypothesized that the clinical tests would demonstrate sensitivity and specificity values >.5 with likelihood ratio for a positive test >1 for diagnosing a labral tear. All patients evaluated by an orthopaedic surgeon specializing in hip arthroscopy for a musculoskeletal hip problem were included in the study. These 85 subjects had a mean age of 41 (range 15-76 SD 14.9) with 40 females and 45 males. 41% of the subjects reported their symptom duration to be 1 year or less while 59% reported their symptom duration to be greater than 1 year. The results of the clinical tests performed by the orthopaedic surgeon were compared to the results obtained by a physical therapist with 15 years experience. Kappa coefficients were calculated to assess inter-tester reliability. As previously documented, the strength of agreement for kappa (κ) was interpreted as follows: ≤ 0=poor, .01-.2=slight, .21-.40 fair, .41-.60=moderate, .61-.80=substantial, .81-.1=almost perfect. The results of the clinical tests were compared to magnetic resonance arthrogram (MRA) results in identifying individuals with a labral tear. Diagnostic accuracy of the clinical test was assessed by calculating sensitivity, specificity, and likelihood ratios. As hypothesized clinical tests had better than moderate agreement with kappa values as follows: Flexion-internal rotation impingement test κ =.69, log roll test κ =.53, greater trochanteric tenderness κ =.72 and FABER test κ =. 45. Diagnostic accuracy of clinical tests in diagnosing individuals with a labral tear was as follows: Flexion-internal rotation impingement test sensitivity =.75, specificity =.07 and a positive likelihood ratio = .81; FABER sensitivity =.65, specificity =.19 and positive likelihood ratio =.80; Flexion with external rotation sensitivity =.29, specificity =.67 and positive likelihood ratio = .89. The flexion-internal rotation impingement test, log roll test and assessment for greater trochanteric tenderness seem to be reliable clinical tests. The reliability of the FABER test seems to less than the other clinical examination tests. While the flexion-internal rotation and FABER had very high sensitivity, the specificity was low. Contrary to this the flexion-external rotation test had low sensitivity but high specificity. Further studies are needed to examine the diagnostic accuracy of these tests when exam findings are clustered together. In conclusion, the results of this study will allow the clinical examination for an individual with a potential labral tear to be more meaningfully interpreted.