Flexor Tendon Injury

What to do right away

1. Press firmly on the wound with a clean cloth for 10 minutes to stop bleeding.
2. Rinse the wound with clean running water and cover it with a clean dressing.
3. Raise the hand above heart level.
4. Remove rings before the finger swells.
5. Do not try to test the finger repeatedly if you suspect a cut tendon, as forceful bending can pull the tendon ends further apart.
6. Get seen the same day at an ER or urgent care. Tell the clinician exactly how the injury happened.

Even small cuts can divide tendons and nerves that lie just under the skin, so do not judge seriousness by the size of the wound.

How flexor tendons work

Two flexor tendons run to each finger:

• FDP (flexor digitorum profundus): bends the fingertip (distal joint)
• FDS (flexor digitorum superficialis): bends the middle joint

The thumb has one, FPL (flexor pollicis longus). These tendons glide through tight tunnels held down by pulleys. Injuries in the area between the palm crease and the middle of the finger were historically called "no man's land" because repair there is technically demanding and scarring is common.

Causes

• Cuts: kitchen knives, broken glass, tools. The most common cause.
• Jersey finger: forceful straightening of a bent finger, typically the ring finger catching on an opponent's jersey in football or rugby, pulls the FDP tendon off its bone attachment.
• Crush injuries.
• Rupture of weakened tendons in rheumatoid arthritis or from bone spurs after wrist fractures.

Symptoms

• inability to bend one or both finger joints
• the injured finger resting straighter than its neighbors when the hand is relaxed (loss of the normal "cascade")
• pain and tenderness along the palm side
• swelling and bruising
• numbness or tingling on one side of the finger, if a digital nerve is cut (digital nerve injury)
• in jersey finger, a tender lump in the palm or finger where the retracted tendon has ended up

Diagnosis

A clinician will examine the hand's resting position and test each joint separately: holding the middle joint straight and asking you to bend the tip tests FDP; holding the other fingers straight and bending the middle joint tests FDS. Sensation and circulation are checked. X-rays look for a finger fracture, glass fragments, or a bone fragment pulled off with the tendon. Ultrasound or MRI can help locate retracted tendon ends. Often the final assessment is done during surgical exploration.

Treatment

Surgery

Flexor tendons cannot reconnect themselves. A hand surgeon sews the ends together with strong stitches, usually within a few days of injury. Repair becomes harder after about 2 to 3 weeks because the muscle shortens and the tendon scars. Delayed injuries may need a tendon graft. Associated nerve and artery injuries are repaired at the same operation.

Jersey finger is ideally repaired within 7 to 10 days, reattaching the tendon to bone.

Hand therapy

Rehabilitation is as important as surgery:

• a protective splint holding the wrist and fingers bent, worn for about 6 weeks
• early, controlled movement exercises, often starting within days, to prevent the tendon sticking to surrounding tissue
• gradually increasing active movement from about 4 to 6 weeks
• strengthening from about 8 to 12 weeks
• return to heavy use and contact sports usually around 3 months

Following the therapy program exactly is critical. Using the hand too soon can rupture the repair, and too little movement causes stiffness.

Complications

• Re-rupture of the repair, often from accidental gripping
• Adhesions: the tendon sticks to scar tissue, limiting movement; may need surgery (tenolysis)
• Stiff joints and contractures, sometimes with triggering similar to trigger finger
• Persistent numbness if a nerve was injured
• Infection

Outlook

Most people regain useful movement and grip, although full normal movement is not always achieved, especially with injuries in the finger. Results are best with early repair, an experienced hand surgeon and committed hand therapy. See also tendon injury for tendon injuries elsewhere and extensor tendon injury for tendons on the back of the hand.

Frequently asked questions

What are the signs of a cut flexor tendon?

The main sign is being unable to bend a finger joint after a cut on the palm side of the hand or finger. The finger may rest straighter than the others. Numbness on one side of the finger suggests a nerve is also cut.

Can a flexor tendon heal without surgery?

No. A completely cut or torn flexor tendon cannot rejoin by itself because the ends pull apart. Surgery is needed to restore the ability to bend the finger. Partial cuts of less than about half the tendon width may be treated without repair.

How long does flexor tendon repair take to heal?

The repair takes about 12 weeks to become strong. You will usually wear a splint for about 6 weeks, do hand therapy for 3 months or longer, and return to heavy work or contact sport around 3 months after surgery.

What is jersey finger?

Jersey finger is an injury where the tendon that bends the fingertip is torn from the bone, usually when a finger catches on an opponent's jersey. The fingertip cannot bend. It needs surgical repair, ideally within about a week.