Empty can and drop arm tests for cuff rupture : Improved specificity after subacromial injection

Shoulder disorders are common in the general population : they occur in about 25 of every 1000 patients per year. A rather large majority are caused by cuff disorders. Differentiating between impingement and cuff rupture is essential to adequate treatment. Clinical tests have been developed, but their accuracy is limited. This study was performed to improve clinical accuracy by combining single tests and adding a subacromial injection. We postulated that the empty can and drop arm tests would result in higher sensitivity and specificity after subacromial injection.Method : We prospectively assessed 49 patients with the empty can and drop arm tests and used ultrasound to compare the individual and combined results.Results : The ultrasound found six cuff ruptures. Specificity improved and sensitivity decreased after subacromial injection.Conclusions : Only specificity improved after subacromial injection. Combining the test results led to an increase in both sensitivity and specificity without injection.