Extensor Tendon Injury

Urgent care recommended

Extensor tendon section requires rapid surgical repair to avoid tendon retraction and optimize recovery.

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What is an extensor tendon?

The extensor apparatus allows fingers and wrist to extend (straighten). It consists of two systems: a tendon system and a retinacular system (ligaments that hold tendons in place). Located on the back of the hand and fingers, just under the skin, extensor tendons are more superficial than flexors and therefore more exposed to trauma (wounds, cuts).

How does an extensor apparatus injury present?

After a wound on the back of the hand or finger, the patient notices inability or difficulty extending the injured finger. Injuries are classified into 9 zones, each requiring specific treatment.

Some presentations are characteristic:

• Mallet finger: Inability to extend the last finger phalanx, following tendon section or avulsion at its distal insertion.
• Boutonnière deformity: Flexion of the proximal interphalangeal joint (PIP) with hyperextension of the distal joint (DIP), indicating rupture of the central extensor band.

Warning signs

Wound on back of hand, finger or wrist
Inability to actively extend finger or wrist
Finger dropping in flexion ("mallet finger" or "boutonnière")
Characteristic deformity according to affected zone

⚠️ Special attention to bite wounds in zone 5 (MP joint): Major infection risk requiring urgent surgical lavage!

How is an extensor tendon section treated?

Treatment depends on the affected zone:

Mallet finger

A splint maintaining the fingertip in extension, worn continuously for 6 to 8 weeks, is often sufficient. Surgery may be necessary in some cases (associated fracture, splint failure).

Injuries in zones 3 to 9

Surgical suture is generally necessary. The intervention is performed under regional anesthesia, most often outpatient.

⚠️ Special attention must be paid to bite wounds in zone 5 (back of metacarpophalangeal joint): Infection risk is major and requires urgent surgical lavage and antibiotic therapy.

What happens after the intervention?

Splint immobilization is implemented, followed by progressive rehabilitation. Controlled early mobilization is essential to prevent adhesions while protecting the repair.

Is extensor tendon surgery risk-free?

No, of course not. As with any surgery, complications can occur:

Adhesions

Main complication, they particularly limit finger flexion. Prevention relies on controlled early mobilization.

Secondary ruptures

They limit active extension and may require surgical revision if significant.

Infection

Major risk in case of bite, requiring urgent surgical lavage and antibiotic therapy.

Other complications

Healing difficulties, stiffness, algodystrophy.

What is the prognosis?

Prognosis is generally good in most cases, provided appropriate treatment and rigorous rehabilitation. Results are overall better than for flexor tendons.