How are impingement and rotator cuff tears diagnosed?

With a careful history and physical examination, impingement and rotator cuff tears can be easily diagnosed in the doctor's office. Further testing may be necessary to determine the exact nature of a rotator cuff tear.

After the evaluation of symptoms, the doctor will perform certain muscle tests to determine whether there are tears in the rotator cuff tendons and to rule out other conditions. The doctor may place the arm in positions that reproduce the described pain to confirm the diagnosis.

There are many tests that can isolate specific areas of pain and weakness to help make the diagnosis. Further evaluation may include:

• A diagnostic injection can help the doctor distinguish between impingement syndrome and a full thickness rotator cuff tear. A local anesthetic is injected into the inflamed bursae to eliminate the pain. If strength in the shoulder returns once the pain is blocked, it is likely that the weakness was due to pain and the rotator cuff tendons are not torn. A rotator cuff tear is suspected if strength does not return while the pain is blocked.
  

• X-rays can reveal signs of arthritis, fractures, and bone spurs on the acromion. They can also reveal changes in position of the humerus and scapula that may suggest a rotator cuff tear. These images are frequently negative in the early stages of injury since X-rays show bone structure but not soft tissue.
  

• An MRI (Magnetic Resonance Image) allows the physician to see muscle and other soft tissue not visible with X-ray.
  

• An arthrogram is another method used to help diagnose a rotator cuff tear. A dye is injected into the shoulder and X-rays are made. If a tear in the rotator cuff tendons exists, the dye will run through the tear and make it visible on X-ray.
  

• Ultrasound may also be used to diagnose a tear; however, results with this technology are difficult to evaluate and are very dependent on the skills of the technician and radiologist.