By: 25 October 2011

Joo Han Oh, MD, PhD, et al
The American Journal of Sports Medicine. July 2010. Vol. 38. No. 7. Pp. 1383-1388

According to researchers from Seoul, Korea, it is possible to predict pain reduction after rotator cuff repair, in what they say is the first study of its kind.

It is done by an injection of lidocaine into the subacromial space, to provide substantial pain relief when impingement is the real problem. The authors called this test the modified impingement test because of the injection of lidocaine as well.

Patients rated their pain when lifting their arms overhead before and after the injection. They were rechecked a year later after complete recovery from shoulder surgery. Surgery was done to decompress the pinched tissue and repair the torn tendon in 153 patients. All patients included had a full-thickness rotator cuff tear. The tests used to see if pain levels and function had changed included the visual analog scale (VAS), the Constant score, and the Simple Shoulder Test.

The surgeons found a definite correlation between pain relief with the subacromial injection before surgery and pain relief after surgery – the modified impingement test could accurately predict how much pain relief patients can expect after a decompression procedure and rotator cuff repair. And the test was predictive no matter what size tear was present.

The size of the tear was used to guide rehab after surgery. Patients with small tears were able to take the arm out of the abduction brace earlier (after four weeks). This compares with five weeks of immobilization for patients with medium tears and six weeks for large tears. Likewise, patients with smaller tears were allowed to move the arm sooner than patients with large or massive tears.

The authors concluded that their modified impingement test is simple, safe, and easy to do. It provides a fairly accurate estimate of how much pain relief patients can expect with rotator cuff repair surgery. It’s not a good predictor of how much change in motion or function they might expect from before to after surgery. But since pain is the primary symptom of concern, knowing pain will be relieved may be enough to satisfy patients and help them when making the decision to have surgery.