Intersection syndrome is when tendons in a person’s wrist and back of the forearm become inflamed and swollen. It is a rare form of tendonitis. People who play certain sports may be at an increased risk.

Tendons are thick cords of fibrous tissue that connect muscles and bones. Tendons cross over each other in the wrist, and some actions can make them rub against each other, causing friction. The National Center for Biotechnology Information (NCBI) explains that this friction can lead to tenosynovitis or swollen tendons.

Many tendons pass through the wrist in six anatomical tunnels called extensor tendon compartments. The NCBI notes that intersection syndrome (IS) occurs when tendons from the first compartment cross over and rub against those from the second.

This article explains what causes IS and how doctors diagnose and treat it. It also looks at home remedies and how to prevent it.

Illustration of the hand and wrist showing where tendons intersect.Share on Pinterest
Medical Illustration by Bailey Mariner

IS describes a form of tendonitis in a person’s wrist. It starts at the point where two tendons cross over or intersect. According to the NCBI, IS refers specifically to tendinitis that starts where tendons from the first and second extensor compartments overlap.

IS is a rare form of tendonitis, most commonly affecting people who repeatedly bend and straighten their wrists. Office workers or anyone else who repeatedly does repetitive motions with their wrists can develop this. However, regularly participating in sports, such as rowing, mountain biking, horseback riding, racket sports, and skiing, may make a person more susceptible to IS.

The repetitive movements cause friction at the point where two tendons that straighten or extend intersect with the fingers and thumb. The rubbing action makes the tendons swell, causing inflammation and pain.

Learn more about tendinitis here.

Most people with IS have a painful spot on the back of their wrist, stretching down a little into the back of their forearm. A 2021 paper explains that the pain is usually on the thumb side of the wrist, starting about 0.5 inches (in) below the wrist joint and extending just over 2 inches down the arm.

Many people experience a rubbing sensation when moving a wrist, there may be swelling, and the area may feel warm to the touch. Some people might find that the pain intensifies when they bend or straighten the wrist.

Others find that the wrist squeaks or makes a creaking noise when they move it. Doctors call this crepitus.

Learn more about crepitus here.

People develop IS by overusing the tendons that extend or straighten their fingers. As the tendons pass through the wrist, they overlap, and when they rub against each other, the friction causes swelling.

The NCBI says risk factors include activities that overuse the wrist, such as:

  • rowing
  • canoeing
  • weightlifting
  • racket sports, including tennis and racquetball
  • horseback riding
  • skiing
  • other repetitive movements

Learn more about wrist tendonitis here.

The Hand and Wrist Institute explains that doctors use the location of a person’s pain to help them diagnose IS.

Other forms of tendonitis, including de Quervain’s tenosynovitis, also produce pain in the back of the wrist and back of the forearm, but in slightly different places.

If they are unsure after a physical exam, doctors may recommend imaging tests, such as an ultrasound, or an MRI, to check where the inflammation starts.

Learn more about de Quervain’s tenosynovitis here.

What else could cause the symptoms?

A 2017 paper highlights the similarities between IS and de Quervain’s tenosynovitis. Both involve inflamed tendons in the wrist, with pain in the forearm, but people experience that pain in slightly different places.

Most people with de Quervain’s tenosynovitis have pain along the outside of their thumb, stretching down into the forearm. People with IS usually feel pain slightly more centrally on the wrist.

Learn more about wrist pain here.

Most doctors recommend people with IS stop doing sporting or other activities that aggravate the wrist to give the injury time to heal.

The 2017 paper explains that people may take over-the-counter (OTC) pain relief and anti-inflammatory medications to help manage their symptoms. They also recommend using ice to reduce swelling, keeping the wrist raised, and bandaging or splinting it to give it more support.

After the initial swelling has gone down, people with IS can start gently stretching and exercising their arm and hand. The idea is to gradually build up the intensity of the exercises over 4–6 weeks until the person has regained their former movement.

Researchers caution against introducing weights initially and advise people with IS to be mindful of their injury when training to avoid any relapses.

Doctors may recommend corticosteroid injections if a person does not recover using these methods. Very occasionally, doctors may suggest a person has surgery to release the tendons.

Find hands and wrist stretching exercises here.

The 2017 paper stresses the importance of doctors explaining what happens inside the wrist to the person with IS. The authors state that by understanding the mechanism of the injury, the person may be able to prevent it from happening again.

If the person’s injury developed due to taking part in a specific sport, they might need to refresh themselves about best practice techniques.

If they experience symptoms again, stopping the activity and resting their arm will prevent the injury from worsening.

Most people with IS fully recover and regain their former movement in the wrist. The NCBI says that most people recover well with conservative treatments and return to their previous levels of movement.

IS is a type of tendonitis in the wrist. It happens when people repeatedly bend and straighten their wrists, making overlapping tendons rub against each other.

The friction between the tendons causes inflammation and swelling, specifically on the back of the forearm, just below the wrist joint.

Doctors usually recommend rest, splinting or bandaging the wrist to support it, and using OTC pain and anti-inflammatory medications as the first-line treatment. If these do not work, they may prescribe corticosteroid injections or, very rarely, surgery.

Most people recover fully and can return to their former levels of activity.