Diagnostic accuracy of clinical tests for the different degrees of subacromial impingement syndrome

Background: Several tests for making the diagnosis of rotator cuff disease have been described, but their utility for diagnosing bursitis alone, partial-thickness rotator cuff tears, and full-thickness rotator cuff tears has not been studied. The hypothesis of this study was that the degree of severity of rotator cuff disease affects the diagnostic values of the commonly used clinical tests. Methods: Eight physical examination tests (the Neer impingement sign, Hawkins-Kennedy impingement sign, painful arc sign, supraspinatus muscle strength test, Speed test, cross-body adduction test, drop-arm sign, and infraspinatus muscle strength test) were evaluated to determine their diagnostic values, including likelihood ratios and post-test probabilities, for three degrees of severity in rotator cuff disease: bursitis, partial-thickness rotator cuff tears, and full-thickness rotator cuff tears. A forward stepwise logistic regression analysis was used to determine the best combination of clinical tests for predicting the various grades of impingement syndrome. Results: The sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy of the eight tests varied considerably. The combination of the Hawkins-Kennedy impingement sign, the painful arc sign, and the infraspinatus muscle test yielded the best post-test probability (95%) for any degree of impingement syndrome. The combination of the painful arc sign, drop-arm sign, and infraspinatus muscle test produced the best post-test probability (91%) for full-thickness rotator cuff tears. Conclusions: The severity of the impingement syndrome affects the diagnostic values of the commonly used clinical tests. The variable accuracy of these tests should be taken into consideration when evaluating patients with symptoms of rotator cuff disease.