What is Scapholunate Dissociation

Scapholunate dissociation is a type of wrist injury. The wrist is made up of eight bones that are arranged in two rows. In the row of bones that is near the bones of the forearm, two bones (scaphoid bone and lunate bone) are connected and held in place by a tough band of tissue (ligament).

Scapholunate dissociation means that this ligament has been torn and the bones have been separated. This injury often happens at the same time that a wrist bone is broken.

This condition can cause wrist pain and weakness.

What are the causes?

This condition is usually caused by a sudden (acute) injury, like a hard fall onto an outstretched hand. The ligament can tear if your hand bends back too far or your wrist twists forcefully.

This condition may also be caused by long-term (chronic) wear and tear on the ligament from overuse. This can happen if you repeatedly use your wrist at work or during sporting activities.

What increases the risk?

The following factors may make you more likely to develop this injury:

• Being elderly or having a higher risk of falling.
• Participating in sports that involve a high risk of falling. These sports include skating, running, and contact sports.
• Using your wrist forcefully at work or in sports.
• Having gout or rheumatoid arthritis.

What are the signs or symptoms?

Pain is the main symptom of an acute injury. You may also feel a tearing sensation and hear a pop if you fall on your hand. Other symptoms include:

• Pain when you bend your wrist, especially pain on the top of the wrist.
• Swelling.
• Tenderness when the top of your wrist is pressed.
• Weakness and stiffness.
• Bruising.
• A clicking sound when you move your wrist.

How is this diagnosed?

This condition is diagnosed based your symptoms, physical exam, and medical history, especially if you have had a recent injury. During the physical exam, your health care provider will check for tenderness over the ligament and pain when moving your wrist. You may also have imaging studies, such as:

• X-rays to check the position and space between the scaphoid and lunate bones.
• MRI to look for ligament damage.

You may also have a procedure to examine your wrist joint with a thin telescope through a small incision (arthroscopy). In some cases, the torn ligament may be repaired during arthroscopy.

How is this treated?

Treatment for this condition depends on the severity of your tear. If you have a partial tear, you may have nonsurgical treatments at first. These may include:

• Wearing a cast or splint on your wrist.
• Icing your wrist.
• Taking NSAIDs to reduce pain and inflammation.
• Starting range-of-motion and strengthening exercises (physical therapy) after your cast or splint can be removed.

You will need wrist surgery if you have a complete tear or if previous treatments have not worked.

Follow these instructions at home:

If you have a splint:

• Wear the splint as told by your health care provider. Remove it only as told by your health care provider.
• Loosen the splint if your fingers tingle, become numb, or turn cold and blue.
• Do not let your splint get wet if it is not waterproof.
• Keep the splint clean.

If you have a cast:

• Do not stick anything inside the cast to scratch your skin. Doing that increases your risk of infection.
• Check the skin around the cast every day. Tell your health care provider about any concerns.
• You may put lotion on dry skin around the edges of the cast. Do not apply lotion to the skin underneath the cast.
• Do not let your cast get wet if it is not waterproof.
• Keep the cast clean.

Managing pain, stiffness, and swelling

• If directed, apply ice to your wrist 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) your wrist above the level of your heart while you are sitting or lying down.

Activity

• Return to your normal activities as told by your health care provider. Ask your health care provider what activities are safe for you.
• Ask your health care provider when it is safe to drive if you have a cast or splint on an arm that you use for driving.
• Do exercises only as told by your health care provider or physical therapist.
• Ask your health care provider if you have any restrictions on lifting or holding anything that is heavier than a certain weight.

Driving

• Do not drive or operate heavy machinery while taking prescription pain medicine.
• Ask your health care provider when it is safe to drive if you have a cast or splint on your arm.

General instructions

• Do not put pressure on any part of the cast or splint until it is fully hardened. This may take several hours.
• Do not use any tobacco products, such as cigarettes, chewing tobacco, and e-cigarettes. Tobacco can delay bone healing. If you need help quitting, ask your health care provider.
• 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. These include visits with a physical therapist, if this applies.
• If your cast or splint is not waterproof, cover it with a watertight plastic bag when you take a bath or a shower.

Contact a health care provider if:

• Your symptoms do not get better or they get worse.
• You have pain, numbness, or coldness in your hand or fingers.
• Your cast or splint becomes loose or damaged.

Get help right away if:

• You lose feeling in your fingers or hand.
• Your fingers or fingernails turn blue or gray.