Flexor vs Extensor Tendon Lacerations of the Finger

As a plastic surgeon at Oregon Cosmetic and Reconstructive Clinic, I have seen patients after a finger cut who are surprised by how much function they’ve lost. At first, the injury may look small. However, if a tendon is involved, the impact can be significant.

To understand why, it helps to know the difference between flexor and extensor tendons — and why timing matters so much for repair.

How Tendons Allow the Finger to Move

Tendons act like strong cords that connect muscle to bone. In the hand, these tendons cross joints and allow the fingers to move smoothly.

The muscles that power finger motion live in the forearm. When those muscles contract, they pull on the tendons. As a result, the finger moves at the joint.

Because of this setup, a cut tendon cannot heal on its own in the correct position. Instead, it often pulls away from the injury site.

What Are Flexor Tendons?

Flexor tendons allow you to bend your fingers and make a fist. This motion is essential for grip, strength, and everyday tasks like holding a cup or turning a key.

In fact, most of what we do with our hands depends on flexion.

When a flexor tendon is cut:

• You may not be able to bend the finger
• Grip strength drops quickly
• Fine motor tasks become difficult or impossible

Because these tendons naturally pull back toward the forearm, early repair is especially important.

What Are Extensor Tendons?

Extensor tendons allow you to straighten the finger. While this motion may seem less powerful, it plays an important role.

Extension helps:

• Move one finger out of the way of another
• Place your hand into a pocket
• Release objects smoothly

When an extensor tendon is cut:

• The finger may droop or lag
• You may not fully straighten the finger
• Coordination between fingers can feel off

Why Timing Matters After a Tendon Laceration

One key concept I explain to patients is muscle memory and tendon pull.

Muscles naturally shorten when they are no longer connected to bone. Because of this, surgeons usually recommend repairing a cut tendon within about two weeks of injury.

If repair is delayed:

• The tendon ends retract
• Surgery becomes more complex
• Results may be less predictable

Early treatment helps restore normal length, tension, and movement.

How Tendon Repair Surgery Works

Tendon repair requires careful, precise surgery.

During the procedure:

• I open the finger (and sometimes the hand)
• I locate both ends of the cut tendon
• I repair the tendon using strong sutures

After surgery, protection is just as important as the repair itself.

Recovery: Protection and Guided Motion

Once the tendon is repaired, healing is only beginning.

Most patients will:

• Wear a splint for about 6 weeks
• Start protected motion early
• Work closely with a hand therapist

This guided movement helps the tendon heal while reducing stiffness and scar tissue. Over time, strength and coordination gradually return.

When to Seek Care

If you have a finger cut and notice trouble bending or straightening the finger, it’s important to seek care promptly. Early evaluation can make a meaningful difference in both surgery and recovery.

At Oregon Cosmetic and Reconstructive Clinic, I focus on restoring function while supporting patients through every step of healing.

Learn more about hand trauma treatment with Dr. Jenq, or book an evaluation.

Frequently asked questions

What is the difference between flexor and extensor tendons?

Flexor tendons let you bend your fingers and make a fist, which you need for grip and most everyday tasks. Extensor tendons let you straighten the fingers, move one finger out of the way of another and release objects smoothly.

Can a cut tendon heal on its own?

Not in the correct position. The muscles that move the fingers are in the forearm, and when a tendon is cut they pull the ends away from the injury, so the tendon usually needs to be repaired surgically.

How soon should a cut tendon be repaired?

Surgeons usually recommend repair within about two weeks of the injury. If repair is delayed, the tendon ends retract, surgery becomes more complex and results may be less predictable.

What is recovery like after tendon repair?

Most patients wear a splint for about 6 weeks, start protected motion early and work closely with a hand therapist. This guided movement helps the tendon heal while reducing stiffness and scar tissue.