Original article
Reliability and Diagnostic Accuracy of 5 Physical Examination Tests and Combination of Tests for Subacromial Impingement

https://doi.org/10.1016/j.apmr.2009.05.015Get rights and content

Abstract

Michener LA, Walsworth MK, Doukas WC, Murphy KP. Reliability and diagnostic accuracy of 5 physical examination tests and combination of tests for subacromial impingement.

Objective

To investigate the reliability and diagnostic accuracy of individual tests and combination of tests for subacromial impingement syndrome (SAIS).

Design

A prospective, blinded study design.

Setting

Orthopedic surgeon shoulder clinic.

Participants

Patients with shoulder pain (n=55, mean age=40.6y).

Interventions

Patients were evaluated with 5 physical examination tests for SAIS: Neer, Hawkins-Kennedy, painful arc, empty can (Jobe), and external rotation resistance tests. Surgical diagnosis was the reference standard.

Main Outcome Measures

Diagnostic accuracy calculated with a receiver operating characteristic (ROC) curve and sensitivity, specificity, positive likelihood ratio (+LR), and negative likelihood ratio (−LR). A forward stepwise binary logistic regression analysis was used to determine the best test combination for SAIS. An ROC curve analysis was also used to determine the cut point of the number of tests discriminating between the presence and absence of SAIS. Kappa coefficients and percent agreement assessed interrater reliability.

Results

The ROC analyses revealed a significant area under the curve (AUC) (AUC=.67–.72, P<.05) for all tests, except for the Hawkins-Kennedy. The tests with a +LR greater than or equal to 2.0 were the painful arc (+LR=2.25; 95% CI, 1.33–3.81), empty can (+LR=3.90; 95% CI, 1.5–10.12), and the external rotation resistance tests (+LR=4.39; 95% CI, 1.74–11.07). Tests with −LR less than or equal to 0.50 were the painful arc (−LR=.38; 95% CI, .16–.90), external rotation resistance (−LR=.50; 95% CI, .28–.89), and Neer tests (−LR=.35; 95% CI, .12–.97). The regression analysis had no specific test combinations for confirming or ruling out SAIS. The ROC analysis was significant (AUC=.79, P=.001), with a cut point of 3 positive tests out of 5 tests. Reliability was moderate to substantial agreement (κ=.45–.67) for the painful arc, empty can, and external rotation resistance tests and fair strength of agreement (κ=.39–.40) for the Neer and Hawkins-Kennedy tests.

Conclusions

The single tests of painful arc, external rotation resistance, and Neer are useful screening tests to rule out SAIS. The single tests of painful arc, external rotation resistance, and empty can are helpful to confirm SAIS. The reliability of all tests was acceptable for clinical use. Based on reliability and diagnostic accuracy, the single tests of the painful arc, external rotation resistance, and empty can have the best overall clinical utility. The cut point of 3 or more positive of 5 tests can confirm the diagnosis of SAIS, while less than 3 positive of 5 rules out SAIS.

Section snippets

Methods

This was a prospective blinded cohort study approved by the Medical Center Investigational Review Board. Consecutive patients presenting with shoulder pain to an orthopedic surgeon's office were invited to participate in this study. To be included in this study, patients had to report shoulder pain for at least 1 week, and shoulder pain had to be their primary complaint. A total of 65 patients were invited to participate; 3 refused to participate, and 7 did not undergo the reference standard

Results

The reference standard surgical findings are summarized in table 1. The prevalence of SAIS was 29%; 16 of 55 patients were confirmed via the gold standard of surgical findings with SAIS either in isolation as the primary diagnosis or in combination with another glenohumeral joint diagnosis. The 39 subjects who did not have a confirmed diagnosis of SAIS were diagnosed via surgical findings with (in order of frequency) glenohumeral instability, glenoid labral tear, rotator cuff tear,

Discussion

To effectively treat patients with shoulder pain, they must first be accurately diagnosed. The physical examination tests used to diagnose shoulder patients should be reliable and accurate. This study has provided clinically useful information to diagnose SAIS. The interrater reliability was fair to substantial for the 5 tests. The painful arc, empty can, and external rotation resistance test individually and the test combination of any 3 positive tests out of 5 have the best ability to confirm

Conclusions

The results of this study provide new and expanded evidence as to the ability of 5 commonly used clinical tests. The single tests of painful arc, external rotation resistance test, and empty can provide the best diagnostic utility and reliability. The Neer test has clinical utility to screen for SAIS but has only fair reliability. Also of diagnostic utility is the use of the cut point of 3+/5 tests, with 3 or more tests positive of 5 useful in confirming SAIS, whereas less than 3 positive of

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