The ECU (extensor carpi ulnaris) tendon is essential in stabilising the ulnar (little-finger) side of the wrist. It can be injured in active people and athletes, causing ECU tendonitis, a tear, or snapping. So what are the symptoms of ECU tendonitis, and how do we treat it?
What is the extensor carpi ulnaris tendon?
The ECU tendon arises from the ECU muscle and attaches to the outer aspect of the elbow. As the tendon reaches the wrist, it passes through a tunnel in the lower part of the ulna, held in place by a strong sheath attached to the bone.
Tension on the ECU tendon is greatest when the wrist is rotated palm-up (supination). In sports that load the wrist in supination, the tendon comes under great strain, leading to injury. Injuries to the ECU tendon include:
- ECU tendonitis
- An ECU tendon tear
- ECU snapping or subluxation
Symptoms of ECU tendonitis
Repeated movement in competitive sport irritates the ECU tendon and its sheath. The sports most associated with ECU tendon problems are golf, tennis, and contact sports such as rugby.
Pain from ECU tendonitis is felt on the ulnar (little-finger) side of the wrist. It can warm up with activity but worsen afterwards, and as it progresses, everyday tasks such as grabbing objects become painful. Other symptoms include swelling, weakness, and reduced range of motion. Any popping, snapping, or tearing sensation may indicate damage to the sheath, which can lead to ECU snapping or subluxation.
How is ECU tendonitis diagnosed?
Your doctor examines the wrist to confirm ECU tendonitis and exclude other causes of ulnar wrist pain, such as a TFCC tear, a lunotriquetral ligament injury, and distal radioulnar joint arthritis.
Typically, there’s tenderness over the ECU tendon, and extending the wrist while moving it outward causes pain. A specific test — the ECU synergy test — is highly accurate for ECU tendon problems: with the elbow bent to 90° and the forearm fully supinated, resisted thumb movement makes the ECU tendon contract and become palpable. Pain along the tendon suggests a problem with the tendon or its sheath.
Imaging helps confirm the diagnosis. An X-ray shows the position of the ulnar and radial bones. Ultrasound shows the tendon and sheath, and, by rotating the wrist during the scan, assesses the tendon’s stability. MRI also shows the tendon structure and excludes other causes of ulnar wrist pain.
Treatment of extensor carpi ulnaris tendonitis
We start with simple anti-inflammatory treatments — ice, topical and oral NSAIDs. Sometimes a wrist splint is needed to rest the tendon. Once the acute pain settles, exercise therapy is essential: simple isometric and eccentric wrist exercises, progressing as strength improves, to help the athlete gradually return to sport.
Extensor carpi ulnaris injection
A cortisone injection into the tendon sheath can help cases that don’t settle with simple treatment. We use ultrasound guidance to improve accuracy and, importantly, to avoid injecting cortisone into the tendon, which would weaken it and raise the risk of rupture.
We place a small needle into the sheath close to the ECU groove, starting with a small dose of local anaesthetic to reduce pain and open up the sheath so the cortisone can be placed accurately.
Sportspeople should be cautious with cortisone, because it can weaken and rupture tendons. Some doctors use PRP as an alternative, as the rupture risk is much lower.
Surgery
Surgery is only considered if simple treatments and an injection don’t help. Some surgeons perform a compartment release, connecting the ECU space with the neighbouring tendon compartments.
Other problems with the ECU tendon
ECU snapping or subluxation
ECU snapping occurs when the tendon sheath tears — either acutely during sport or gradually with repetitive activity. People typically report pain and swelling with a popping or clicking sensation. The tendon slips out of its groove when the wrist is rotated palm-up (supinated) and back into the groove when rotated palm-down (pronated). Ultrasound often shows the tendon moving out of the groove as the wrist rotates.
For ECU snapping from an acute injury, we immobilise the wrist and forearm in a cast for a few months. Surgery may be needed to reposition the tendon if casting doesn’t work.
Frequently asked questions about extensor carpi ulnaris tendonitis
How long does ECU tendonitis take to heal?
There’s no set timeframe, but like other tendonitis, ECU tendonitis can take 3–6 months to settle. Load modification and progressive strengthening speed recovery, while returning to heavy wrist load too soon prolongs it.
How do you tell ECU tendonitis from a TFCC tear?
Both cause ulnar-sided wrist pain and can coexist. The ECU synergy test and careful examination help distinguish them, and imaging — especially ultrasound and MRI — confirms whether the pain is coming from the ECU tendon, the TFCC (wrist cartilage), or the joint.
What is ECU snapping?
It’s when the ECU tendon slips out of its groove as the wrist rotates, usually because the sheath holding it is torn. It causes a popping or clicking sensation on the little-finger side of the wrist and is confirmed by watching the tendon move on ultrasound during wrist rotation.
Where is the extensor carpi ulnaris tendon located?
At the back and ulnar (little-finger) side of the wrist. The tendon attaches to the base of the 5th (little-finger) metacarpal.
Can ECU tendonitis occur in non-athletes?
Not usually. But people with inflammatory arthritis can develop ECU tendon swelling even without sport, and sometimes ECU tendonitis is the first sign of an inflammatory arthritis, so it’s worth bearing in mind where there’s no sporting cause.
Can you avoid surgery for ECU tendonitis?
Usually, yes. Most cases settle with rest, splinting, anti-inflammatories, and rehabilitation, sometimes with a guided injection. Surgery is reserved for cases that fail all these, or for ECU snapping that doesn’t respond to casting.
Final word from Sport Doctor London about ECU tendonitis
ECU tendonitis is common in sports such as golf, tennis, and rugby, and causes pain on the ulnar side of the wrist. Because several other conditions cause ulnar wrist pain, an accurate diagnosis matters. See a sports doctor who can diagnose and manage your wrist pain.
If you have ulnar-sided wrist pain, Dr Masci can assess you in London, including ultrasound and, where needed, an ultrasound-guided injection in the clinic. Contact the team here or call +44 (0) 203 488 0350.
Leave A Comment