Extensor Carpi Ulnaris (ECU) Tendonitis

Inflammation of the ECU tendon is a common condition affecting the little finger side of the wrist. The tendonitis (also termed tenosynovitis) can occur in any person and pain is often aggravated by wrist motion and lifting. Wrist swelling is sometimes seen.

Symptomatic ECU tendonitis is a cause of ulnar-sided wrist pain, with ulnar or ulnaris relating to the little finger side of your wrist. It is named after the ulna bone of the forearm.

There are other causes of wrist pain in the region of the ECU tendon and a thorough assessment will help to identify the cause.

Do you experience pain on the little finger side of your wrist (at the back)?

  • ECU tendonitis is inflammation (and thickening) of the ‘extensor carpi ulnaris’ tendon as it passes beneath a narrow tunnel on the little finger side of your wrist. A size mismatch between the tendon and the tunnel causes pain and mobility issues (the tendon becomes too swollen for the tunnel). Occasionally the inflammation can be associated with a split in the substance of the tendon or a tear in the tunnel with instability of the tendon .

  • The cause of ECU tendonitis remains unknown for most people. Overuse or repetitive movements with sports like tennis or golf or an injury of the wrist can all predispose to this condition.

  • Some of the potential symptoms of ECU tendonitis are listed below.

    Typically present:

    • Pain along the little finger side of your wrist and neighbouring forearm. 

    • Pain that is made worse with most wrist movement.

    • Tenderness when pressing along the site of pain.

    Sometimes present:

    • Swelling at the site of pain.

    • Clicking, snapping or a scratching feeling at the site of pain.

  • It is important to correctly diagnose ECU tendonitis and exclude other causes of wrist pain, such as wrist arthritis, ulnocarpal abutment syndrome and triangular fibrocartilage (TFCC) tears.

    The diagnosis is usually made on the history (your symptoms) and clinical examination. Assessment with an ultrasound scan is sometimes required if the diagnosis is unclear or if a steroid injection is proposed as a treatment. An MRI scan may occasionally be performed.

    • Non-surgical treatment options include simple painkillers, massage with topical anti-inflammatory gel and hand therapy for exercises and splintage. An injection of steroid (e.g. cortisone) at the site of the tunnel in your wrist is sometimes used for intrusive symptoms that are not settling.

    • Surgical treatment is rarely required for ECU tendonitis but debridement (excision of inflamed tissue) can be performed in severe and refractory cases not responding to other treatments. Traumatic and unstable ECU tendonitis is sometimes treated with surgery to stabilise the tendon.

    Matthew offers all the above treatments. He can refer you for hand therapy, splintage and ultrasound assessment (with or without steroid injection) if required.

The information contained on this page is for guidance only and should not be considered a substitute for medical assessment and advice by a suitably trained doctor or clinician. External links have been provided for your information and convenience and we are not responsible for their content or accuracy.