Diagnosis of Rotator Cuff Tears
This can be the most important part of the assessment and can be suggestive of a rotator cuff tear. If I can demonstrate selective restrictive movement and weakness of your shoulder, there is a high likelihood of a tear in the tendons. It is also helpful excluding a frozen shoulder.
These may give clues that there is a rotator cuff tear. It does not image the tendons at all. X-rays may demonstrate the presence of spur formation (which if large is suggestive of a tear) and help exclude arthritis.
In experienced hands, Ultrasonography (US) can non-invasively reveal tears of the rotator cuff. They also can measure accurately the size of the tear. US has the advantages of speed and safety. The disadvantage is that its accuracy is very dependent on the experience of the operator. Due to the variable experience of outside ”operators”, we often repeat the ultrasound in our clinic to confirm the findings and take our own measurements. While US in experienced hands is as accurate, and in some cases more accurate than MRI in diagnosing RC tear, it is not very good at looking at the bones or cartilage.
In some cases, injection of a local anaesthetic into the bursa under ultrasound guidance can be used to make sure that the pain is in fact coming from the shoulder, and not radiating from the neck (The impingement test).
Magnetic Resonance Imaging (MRI)
An MRI scanner is a large machine that uses magnetic waves and a computer to provide a 2 dimensional picture. The MRI Scan can be used to look at the rotator cuff tendons as well as the bones and cartilages. Rarely contrast injection (arthrogram) may be used.