Shoulder surgery to repair a rotator cuff tear is designed to reduce pain, restore power (strength), and improve motion. Patients report that pain relief is by far the most important and best result of this procedure. Is it possible to know before surgery how much improvement in pain might be expected?
According to orthopedic surgeons from Seoul, Korea, it is possible to predict pain reduction after rotator cuff repair. And they say this is the first study of its kind! How is it done? A simple injection of a numbing agent called lidocaine is inserted into the subacromial space.
The subacromial space is the area just above the head of the humerus (upper arm bone) and below the acromion. The acromion is a curved piece of bone that comes around from the back of the shoulder blade over the humeral head.
Muscles of the rotator cuff pass underneath this arch of bone. As the arm lifts up, the damaged (torn) or weak rotator cuff can get pinched between the head of the humerus and the acromion. This condition is called impingement. It’s the pinching of the tendon that causes pain and loss of motion and function.
Injecting a numbing agent into this space would provide substantial pain relief when impingement is the real problem. The authors called this test the modified impingement test. It’s modified because instead of just assessing pain while the arm is lifted, there’s been 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. In other words, 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 (small or large).
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.