Tendon Laceration (Cut Tendon)

First aid for a cut that may involve a tendon

1. Apply firm pressure with a clean cloth to stop bleeding, and raise the hand above heart level.
2. Rinse the wound gently with clean running water.
3. Cover with a clean dressing.
4. Do not test the finger repeatedly by forcing it to move; a partly cut tendon can tear completely.
5. Keep the hand still, ideally in a sling, and seek medical care the same day.
6. Bring the object that caused the cut if it is relevant (for example, glass), as small fragments may remain.

Anatomy: flexor and extensor tendons

On the palm side, nerves and arteries run right next to the flexor tendons, so digital nerve injuries often occur at the same time. See flexor tendon injury and extensor tendon injury.

Symptoms

• inability to bend or straighten one or more joints
• a finger held in an abnormal position at rest (for example, one finger staying straight while the others curl slightly)
• pain on attempting movement
• weakness of grip or push-off
• numbness or tingling if a nerve is also cut
• a small entry wound that looks minor compared with the function lost

A partial tendon cut may still allow movement but with pain and weakness, and can rupture later.

Diagnosis

A clinician will:

• ask how the injury happened and the hand position at the time (tendons can retract, so the cut in the tendon may not line up with the skin wound)
• check how each joint bends and straightens, both actively and against resistance
• watch the resting posture of the fingers (the cascade) and squeeze the forearm to see if fingers move passively (tenodesis test)
• test sensation on both sides of each finger and check circulation
• explore the wound under local anesthetic in good light when appropriate
• order X-rays for glass, metal fragments or fractures, and ultrasound or MRI if the diagnosis is unclear

Treatment

Surgery

Most complete tendon cuts, and partial cuts involving more than about half the tendon, need repair by a hand surgeon:

• Timing: flexor tendons are ideally repaired within days, often within the first week. Delays allow the tendon ends to retract and scar, making repair harder or requiring a tendon graft.
• Procedure: under regional or general anesthesia, the surgeon finds and stitches the tendon ends together, repairs any nerves or arteries, and closes the wound.
• Extensor tendons on the back of the hand can sometimes be repaired in the emergency department; some, such as mallet finger, are treated with splinting alone.

Wound care and infection prevention

Cleaning, antibiotics when indicated (especially bites and contaminated wounds), and tetanus vaccination if not up to date.

Rehabilitation

Hand therapy is as important as surgery:

• a custom splint protects the repair for about 4 to 6 weeks
• carefully controlled early movement exercises, started within days, prevent the tendon from sticking to surrounding tissue
• strengthening begins around 8 to 12 weeks
• heavy lifting and gripping are usually avoided until about 12 weeks

Complications

• Rupture of the repair, most often from using the hand too early
• Adhesions: scar tissue that limits tendon gliding and causes stiffness; sometimes needs surgery (tenolysis)
• Joint stiffness
• Infection
• Persistent numbness from nerve injury
• Reduced grip strength

Recovery and outlook

Tendons heal slowly. Most people regain good function, though some stiffness or weakness can persist, especially after flexor tendon injuries in the fingers (the area historically called "no man's land"). Following hand therapy instructions closely is the most important factor in a good outcome. Return to light activities usually takes 8 to 12 weeks, and full strength 3 to 6 months or longer.

Frequently asked questions

How do I know if I cut a tendon?

The main sign is being unable to bend or straighten a finger, thumb or joint normally after a cut, or a finger resting in an unusual position. Pain on movement, weakness and numbness can also occur. Any of these after a cut need same-day assessment.

Can a cut tendon heal without surgery?

Small partial cuts may heal with splinting. Most complete cuts, especially of flexor tendons in the fingers, do not heal properly on their own because the ends pull apart. Surgery within days gives the best results.

How long does it take to recover from tendon repair?

The tendon takes about 12 weeks to heal strongly enough for normal use. Splints are worn for 4 to 6 weeks, followed by therapy. Full recovery of movement and grip strength can take 3 to 6 months or longer.

What happens if a cut tendon is not repaired?

An unrepaired tendon usually leaves permanent loss of movement and weakness. Over time, the tendon ends retract and the muscle shortens, so later repair often needs more complex surgery such as a tendon graft, with less predictable results.