How to Diagnose ECU Tendonitis

The extensor carpi ulnaris (ECU) is a small muscle in the forearm that helps extend and adduct the hand. Extension is the action of pulling the back of your hand closer to your wrist, and adduction is bending the hand outward toward the pinkie finger. The ECU starts on the lateral epicondyle (outside edge) of the elbow, and ends on the base of the fifth finger (the top side of the pinkie). Tendonitis of the ECU is primarily caused by overuse actions, such as repetitive typing in which the pinkie is often used.

Instructions

• 1

  Ask yourself questions to help identify the cause of the problem. What increases or decreases the amount of pain? With ECU tendonitis, the pain will increase with active movement---extending and adducting the hand---and passive stretching of the muscle. Also, is there a history of overuse or injury with the hand or wrist?

• 2

  Look for anything that does not match your un-injured hand, such as swelling, redness or deformity. With ECU tendonitis, some swelling may be seen in the wrist or on the back of the hand, or there may be none at all. Notice if you are using the injured hand differently than the uninjured hand, as this may be the result or eventual cause of another injury.

• 3

  Use the fingers of your non-injured hand to press along the length of the muscle, starting on the outside edge of the elbow, and continuing down into the wrist and ending on the back of the pinkie finger. Patients with ECU tendonitis usually report increased pain when pressing on the tendon itself. You may also feel some "crunching" or swelling when this test is performed. Both of these symptoms are consistent with ECU tendonitis.

  To locate the muscle and tendon, extend only your pinkie finger while holding the other fingers and wrist still. Place the fingers of your other hand gently on the top of the injured hand's wrist (near the outside edge, roughly in line with the pinkie) and repeatedly extend the pinkie finger; you should feel the tendon moving slightly beneath your fingers.

• 4

  To test the ECU muscle specifically, place your hand palm-side down on a table or desk, with the hand off the edge. Keep the wrist straight and make a loose fist with all your fingers, but extend only the pinkie. Using the uninjured hand, press down gently on the pinkie just beyond where the finger connects to the hand. Try to resist this motion with the pinkie of the injured hand. If there is pain with this test, it is likely that the ECU is involved.

• 5

  The hand is controlled by a large number of muscles that lie close to one another, and it is difficult for those without medical experience---and sometimes even for those with experience---to correctly diagnose injuries to the wrist or hand. These tests are designed only to assist you if you suspect a tendonitis injury to this particular muscle. If the pain is severe or is accompanied by a loss of function or deformity, see a doctor for treatment.