Objective: To evaluate the reliability and diagnosis accuracy of 5 special tests used for the diagnosis of subacromial impingement syndrome (SAIS).
Methods: A prospective blinded cohort study was taken,in which 105 patients with shoulder pain were reviewed. All the patients took 5 special syndrome tests including Neer syndrome, Hawkins-Kennedy syndrome, painful arc empty can test and external rotation resistance test, also underwent arthroscopic surgical examination. The Nikolaus's criterion was regarded as a golden standard for SAIS. Data accuracy analysis was calculated through a receiver operating characteristic (ROC) curve, sensitivity, specificity, positive likelihood ratio (+LR) and negative likelihood ratio (-LR). The binary Logistic regression analysis was used to find out the best test combination for ruling in or out SAIS. The interrater reliability was assessed by the Kappa coefficient and percent agreement.
Results: The ROC analysis indicated a significant area under the curve (AUC) (AUC=0.62 to 0.73, P<0.05) for all tests except the Hawkins-Kennedy. Tests with a +LR greater or equal to 2.0 were the painful arc,empty can,external rotation resistance, Tests with a-LR less than 0.5 were Neer,painful are ,external rotation resistance. The regression analysis found the painful arc, empty can and external rotation resistance made the best combination for diagnosis SAIS,while the painful are and external rotation resistance made the best combination for ruling out SAIS. The difference of ROC analysis was significant with a cut-off of 3 positive tests out of 5 tests. All tests had moderate to good agreement (Kappa=0.42 to 0.71).
Conclusion: The single test of painful arc, empty can and external rotation resistance, as well as 3 or more positive tests of the 5 tests can help confirm the diagnosis of SAIS, while the single test of Neer, painful arc and external rotation resistance are help rule out the diagnisis of SAIS. The tests of painful arc, empty can and ex ternal rotation resistance are the best combination for the diagnosis of SAIS (when 2 or more are positive), while the tests of painful arc and external rotation resistance are the best combination for ruling out SAIS (when both are negative)