Rupture of the extensor pollicis longus (EPL) tendon will prevent full straightening (extension) of the terminal or end joint of the thumb (called the interphalangeal joint or IPJ). The EPL tendon runs across the dorsum (back) of the wrist and connects the thumb to the EPL muscle in the forearm. The tendon runs in a short and tight tunnel at the back of the wrist where it is susceptible to the effects of distal radius (wrist) fractures.

Wrist (distal radius) fractures treated in a cast without surgery are at risk of EPL tendon rupture. The EPL tendon passes through a short tight tunnel at the dorsum (back) of the wrist where it is susceptible to local irritation from a distal radius fracture. The exact cause of rupture in such patients is not fully understood, but reduced EPL tendon blood supply and nutrition within the tunnel (due to increased pressure) is a likely factor.

The EPL tendon is usually unaffected by more severe wrist fractures or those treated with an operation.

Other rarer causes of EPL tendon rupture include wrist osteoarthritis, inflammatory arthritis (like rheumatoid), previous tendon injury (causing weakness), and rupture from metal plates or screws placed into the wrist by a surgeon.

Some of the potential symptoms of EPL tendon rupture are listed below.

Typically present:

• Sudden inability to fully straighten the thumb (especially at the terminal or end joint).

• Inability to lift the thumb from off a table when the hand is placed flat (a movement called retropulsion).

Sometimes present:

• Pain, swelling or bruising along the tendon or wrist.

• Sudden “ping” at the time of tendon rupture.

Pain, if present, does not usually last beyond the first few days or weeks.

It is important to correctly diagnose thumb extensor (EPL) tendon rupture and exclude other causes of thumb dysfunction, such as trigger thumb.

The diagnosis is usually made on the history (your symptoms) and clinical examination. Plain radiographs (X-rays) and an ultrasound scan are commonly performed.

Some people will manage well with thumb extensor (EPL) tendon rupture and choose not to pursue any treatment.

• Non-surgical treatment will not restore the movement lost from EPL tendon rupture. Options include simple painkillers, massage with topical anti-inflammatory gel and hand therapy for exercises and a thumb splint.

• Surgical treatment options include tendon transfer (to help restore thumb movement) or fusion of the terminal or end joint of the thumb (to stabilise in a functional position). Direct repair of the frayed tendon ends is not usually possible.

  Tendon transfer: this common reconstructive technique reroutes a nearby tendon and attaches it to the ruptured end of the EPL tendon. The tendon transfer uses an extensor tendon from the index finger (called the extensor indicis proprius or EIP) and is performed through three separate skin incisions (one at the wrist, one at the base of the index finger, and one near the thumb base). 

  There are usually two extensor tendons that straighten the index finger and rerouting the EIP tendon to the thumb is usually very well tolerated.

  Protection of the tendon transfer with a thumb splint (and exercises guided by a hand therapist) is required for at least 6 weeks.

  Fusion: this option fixes the terminal thumb joint (called the interphalangeal or IP joint) in a straight position. All movement at the fused joint is removed. Fusion can help to stabilise the thumb for pinch grip, especially in those with a highly mobile IP joint and/or in those who want to avoid tendon transfer. Fusion removes the opposing joint surfaces (including the cartilage) and is achieved using a screw or wires.

  Following surgery, bony fusion will take at least six weeks. During this time the thumb is protected and immobilised in a splint.

  Although fusion surgery avoids the more prolonged rehabilitation (guided by a hand therapist) that is required following tendon transfer, it removes all movement from the IP joint.

Matthew offers all the above treatments. He can refer you for hand therapy if required.

EPL tendon surgery is often performed under local anaesthesia. Matthew typically uses the WALANT anaesthetic technique which avoids the use of an arm tourniquet (avoiding tourniquet pain). Click here for an overview of the different types of anaesthesia and the general risks of hand surgery.

The specific risks associated with tendon transfer for thumb extensor (EPL) tendon rupture will be discussed if surgery is an option, but includes stiffness, scar issues, numbness and (occasionally) the inability to independently point with the index finger.

You can read more detailed information about thumb extensor (EPL) tendon rupture on the Lothian Hand Unit website.

The British Society for Surgery of the Hand (BSSH) has an informative webpage on thumb extensor (EPL) tendon rupture, which can be downloaded as a patient information leaflet PDF.