Combining results from hip impingement and range of motion tests can increase diagnostic accuracy in patients with FAI syndrome

Purpose Clinical examination is an important part in the diagnosis of femoroacetabular impingement (FAI) syndrome. However, knowledge on reliability and validity of clinical diagnostic tests is scarce. The aims were to evaluate the inter-rater agreement and diagnostic accuracy of clinical tests to detect patients with FAI syndrome. Methods Eighty-one patients (49% women) were recruited. Two experienced raters performed impingement and range of motion (ROM) tests. Three criteria had to be fulfilled for the diagnosis of FAI syndrome: (1) symptoms; (2) CAM and/or Pincer morphology; and (3) being responder to intra-articular block injection. For inter-rater agreement, the Cohen’s kappa statistics were used (0.41–0.60 = moderate, 0.61–0.80 = substantial agreement). For diagnostic accuracy, sensitivity, specificity, positive and negative predictive values were calculated. Results Anterior impingement test (AIMT), FADIR test and FABER test showed kappa values above 0.6. All passive hip ROM, except extension, had kappa values above 0.4. AIMT and FADIR showed the highest sensitivity, i.e., 80%, with a specificity of 26% and 25%, respectively. Passive hip ROM in internal rotation with neutral hip position had a sensitivity of 29% and a specificity of 94%. Conclusion The AIMT, FADIR and FABER tests were reliable between two experienced raters, while results from different raters for hip ROM should be interpreted with caution. The AIMT and FADIR test can only be used to rule out patients with FAI syndrome, while evaluation of ROM in internal rotation with neutral position may be more suitable to rule in patients with FAI syndrome. Level of evidence II.