What is Extensor Carpi Ulnaris Instability
Tendons attach muscles to bones. They also help with joint movements. When a tendon is injured or it moves out of its normal position, the joint movements can be affected.
The extensor carpi ulnaris (ECU) tendon is located on the back of the wrist, on the side that is closest to the little finger. It runs under a band of fibrous tissue (extensor retinaculum) to stabilize its position in the wrist.
This tendon helps with extending or bending back your wrist and angling your wrist toward your body. It also helps with gripping and pulling items close to your body.
Injury to the ECU may result in ECU instability and hand and wrist weakness. Damage to the retinaculum causes the ECU tendon to slip in and out of the bony groove (subluxation) that it normally lies in or to come out of the groove completely (dislocation).
What are the causes?
This condition often happens with repeated activities that require forceful rotation or extension of the wrist. Other causes of ECU instability include:
- Forced (traumatic) rotation of the wrist to a palm-up position.
- A shallow or malformed groove in the bone where the ECU normally lies.
What increases the risk?
This condition is more likely to develop in:
- People who play sports that include repeated, forceful turning up of the wrist into a palm-up position, such as tennis, golf, and weight lifting.
- People who have had a previous wrist injury.
- People who have poor wrist strength and flexibility.
- People who do not warm up properly before activities.
What are the signs or symptoms?
Symptoms of this condition include:
- Painful or painless “snapping” feeling over the back of the wrist—on the little finger side—when you rotate your wrist into the palm-up position.
- Swelling of your injured wrist.
- Pain when the injured area is touched.
- Weakness in your wrist when you turn it to the palm-up position.
How is this diagnosed?
This condition is diagnosed with a medical history and physical exam. You may also have imaging studies to confirm the diagnosis. These can include:
- Ultrasound.
- MRI.
How is this treated?
Treatment may include the use of icing and medicines to reduce pain and swelling. You may also be advised to wear a splint or brace to limit your wrist motion. In less severe cases, treatment may also include working with a physical therapist to strengthen your wrist and stabilize your ECU. In severe cases, surgery may be needed.
Follow these instructions at home:
If you have a splint or brace:
- Wear it as told by your health care provider. Remove it only as told by your health care provider.
- Loosen the splint or brace if your fingers become numb and tingle, or if they turn cold and blue.
- Keep the splint or brace clean and dry.
Managing pain, stiffness, and swelling
- If
directed, apply ice to the injured area.
- Put ice in a plastic bag.
- Place a towel between your skin and the bag.
- Leave the ice on for 20 minutes, 2–3 times per day.
- Move your fingers often to avoid stiffness and to lessen swelling.
- Raise (elevate) the injured area above the level of your heart while you are sitting or lying down.
General instructions
- Return to your normal activities as told by your health care provider. Ask your health care provider what activities are safe for you.
- Take over-the-counter and prescription medicines only as told by your health care provider.
- Keep all follow-up visits as told by your health care provider. This is important.
- Do notdrive or operate heavy machinery while taking prescription pain medicine.
Contact a health care provider if:
- Your pain, tenderness, or swelling gets worse, even if you have had treatment.
- You have numbness or tingling in your wrist, hand, or fingers on the injured side.
