Extensor Carpi Ulnaris (ECU) Subsheath Rupture Treatment

Tendons are strong, fibrous tissues that connect muscles to bones. They glide through a tunnel, or sheath, when muscles contract. The extensor carpi ulnaris (ECU) is a major tendon that connects the forearm to the wrist. Located on the ulnar side (small finger side) of the forearm, the ECU tendon runs from the elbow to the top of the ulna bone, where it’s held in place at the base of the small finger by the ECU tendon subsheath.

A sudden twisting of the wrist can cause the subsheath to rupture, allowing the tendon to snap in and out of place. This condition is sometimes referred to as “snapping wrist” because it creates a snapping or popping sensation when the wrist moves. The condition is painful and can damage the tendon over time.

Extensor carpi ulnaris injuries most commonly happen to athletes who grip and rotate sticks, rackets, clubs, or bats. Ruptures of the ECU subsheath can occur due to a sudden and forceful twisting of the wrist. They can also result from repetitive motions over a long period of time that place stress on the wrist.

ECU subsheath rupture is most common in these sports:

• Racket sports (e.g. tennis, squash, racket ball)
• Golf
• Baseball
• Hockey

Pain over the ulnar side of the wrist is a common symptom of an extensor carpi ulnaris subsheath rupture. Other common symptoms include:

• Wrist pain over the ECU tendon
• Tenderness over the ECU tendon
• Snapping or popping sensation when twisting the wrist
• Swelling
• Limited range of motion

If you have symptoms of a possible ECU subsheath rupture, you should go see your doctor as soon as possible. Your doctor will take a medical history and conduct a physical examination of your wrist. X-rays are not routinely necessary for a diagnosis, though sometimes they can be helpful to rule out other causes of ulnar-sided wrist pain. If an ECU subsheath rupture is suspected, imaging tests such as a magnetic resonance imaging test (MRI) may be ordered to view the soft tissue around the wrist.

Treatment of an extensor carpi ulnaris subsheath rupture will depend on the severity of the injury. If non-surgical treatment is indicated, your doctor will manually put the tendon back in its position and immobilize the ECU subsheath to give it time to heal. Additional common conservative treatments include:

• Rest from activities that place stress on your wrist
• Immobilizing the wrist in a splint or cast for approximately three months
• Anti-inflammatory medication
• Hand therapy with a licensed professional

Try these exercises to help address your condition:

Below is a PDF of the exercise program.

ECU Subsheath Rupture

Many cases of ECU subsheath rupture can successfully be treated without surgery. However, especially for athletes, surgery may be required to repair the sheath to hold the tendons in place if significant damage has occured. Your doctor can advise on whether surgery may be right for you.

After surgery to treat an extensor carpi ulnaris subsheath rupture, a period of immobilization for four to six weeks is typical. During this time, it is important to keep your hand elevated and your fingers moving to try to prevent stiffness and decrease swelling. Once the splint or cast is removed, a referral to a physical or hand therapist is common to help maximize wrist range of motion. Athletes usually return to play about three months following an ECU subsheath rupture.