Diagnosis
Impingement syndrome can usually be diagnosed by history and physical exam. On physical exam, the physician may twist or elevate the patient's arm to test for reproducible pain (Neer's sign and Hawkin's sign). These tests help localize the pathology to the rotator cuff, however they are not specific for impingement. Neer's sign may also be seen with subacromial bursitis.
The physician may inject lidocaine (usually combined with a steroid) into the joint, and if there is an improved range of motion and decrease in pain, this is considered a positive "Impingement Test". It not only supports the diagnosis for impingement syndrome, but it is also therapeutic.
Plain x-rays of the shoulder can be used to detect some joint pathology and variations in the bones, including acromioclavicular arthritis, variations in the acromion, and calcification. However, x-rays do not allow visualization of soft tissue, thus hold a low diagnostic value. Ultrasonography, arthrography and MRI can be used to detect rotator cuff muscle pathology. MRI is the best imaging test prior to arthroscopic surgery. Due to lack of understanding of the pathoaetiology, and lack of diagnostic accuracy in the assessment process by many physicians, several opinions are recommended before intervention.
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