Snapping ECU and Ulnar Sided Wrist Problems

The ECU tendon, or extensor carpi ulnaris, is one of the major wrist tendons.  It is on the ulnar side of the wrist, the same side as the small finger.  The tendon starts on the back of the forearm, but at the level of the wrist joint it is directly on the side of the joint.  There are a number of causes of ulnar sided wrist pain, and one of those are problems with the ECU tendon.  The two most common ECU tendon problems are tendonitis and tendon subluxation.

ECU tendonitis is the result of inflammation of the ECU tendon.  This condition is most common in nonathletes, and generally occurs without an obvious cause.  Sometimes patients with ECU tendonitis have symptoms that occur following a traumatic injury, such as a wrist fracture, but the most common scenario is without an obvious source.

Signs of ECU tendonitis include:

• Tenderness directly over the ECU tendon
• Swelling or fullness of the tendon sheath
• Crepitus with movement of the wrist
• Pain with resisted ulnar deviation (pointing the wrist to the pinky side)

Tests are generally performed to evaluate for other sources of wrist pain.  X-rays would be normal for most patients with tendonitis, and an MRI might show some fluid around the tendon.  Sometimes your doctor will perform a test by injecting a numbing medications (lidocaine) around the tendon to see if the pain resolves. 

Typical treatments include rest, ice application, anti-inflammatory medications, and the use of a wrist splint.  If symptoms persist after simple treatments, an injection of cortisone can be helpful.  Seldom is a surgical procedure needed for treatment of ECU tendonitis, but if symptoms persist despite appropriate management, a surgical debridement of the tendon can be considered.

Snapping ECU syndrome is a condition due to the ECU tendon sliding in and out of its groove on the side of the wrist.  Snapping ECU is more common in athletes, and generally follows a traumatic injury to the wrist.  The injury causes damage to the normal tendon sheath, and allows the tendon to slide out of its normal location.

Signs of ECU subluxation include:

• Painful snapping of the wrist with twisting movements
• Tendon snapping out of its groove with turning the hand to a palm-up position
• Tendon snaps back into place when the hand is turned palm down

Normally, the ECU tendon runs within a smooth sheath along a groove on the side of the wrist joint. It is held in this position by a ligament. Sometimes after an injury such as a wrist fracture, this tendon sheath can become unstable. If the ECU tendon is not held in place, it may 'snap' over the bone as the wrist is rotated.  Treatment may be successful by immobilizing the wrist with the tendon in proper position.  If this is not effective, treatment may require surgical reconstruction of the tendon sheath so the tendon will stay in its proper position.