Finger Flexor Tendon Injury: Symptoms, Surgery, and Rehabilitation | Guide | Artur Soczka, MD, PhD

Why flexor tendons matter

Flexor tendons enable finger flexion and precise hand movements — gripping, pinching, typing, and playing instruments. Damage causes immediate loss of finger function and significantly impairs the entire hand. Even a seemingly minor injury can have a major functional impact.

How flexor tendon injuries occur

The most common cause is a laceration from a sharp object — a knife, glass, or metal. Less commonly: crush injury, burns, or sports trauma. The skin wound is often small, while the underlying structural damage is far more serious.

Avulsion injuries: jersey finger

Flexor tendon injuries can also occur without any skin break. An avulsion injury results from sudden forceful tension that tears the tendon from its bony attachment.

This can happen during everyday activities — for example, a sudden forceful finger flexion while gripping an object. In sport, the classic mechanism is "jersey finger": an athlete grabs an opponent's shirt and the ring finger flexor digitorum profundus (FDP) tendon is avulsed, causing inability to flex the distal interphalangeal joint.

Spaghetti wrist injury

A small laceration at the wrist can cause extensive deep structural damage — simultaneous injury to multiple flexor tendons, nerves, and blood vessels. Known as "spaghetti wrist injury" in medical literature, it requires urgent surgical intervention. A small-looking wound should never be dismissed.

Typical symptoms

• inability to actively flex a finger,
• weakened grip,
• wound on the finger or palm,
• pain on attempted finger movement.

Numbness or altered sensation may also indicate concurrent nerve injury.

Why timing is critical

After laceration, the tendon retracts toward the forearm. The sooner surgical repair is performed, the easier it is to locate and repair the tendon ends — and the better the functional outcome. Delayed treatment makes reconstruction significantly harder and worsens the prognosis.

The most common mistake

Dismissing a small wound on the palm or finger. If a finger does not flex normally after a cut, urgent specialist evaluation is essential.

Diagnosis

Diagnosis is based on careful clinical examination, assessing each flexor tendon individually. Ultrasound may be used to confirm tendon continuity and localise the retracted end.

Surgical treatment

Lacerated flexor tendons require microsurgical repair. In complex injuries, concurrent repair of damaged nerves or blood vessels may be necessary. Precise surgical technique is essential for subsequent finger mobility.

Rehabilitation — the key to recovery

Post-operative hand therapy must be precisely timed: loading too early risks suture failure; starting movement too late leads to adhesion formation. Specialist therapy has a major impact on the final outcome and should be undertaken with an experienced hand therapist.

When to seek urgent care

Seek urgent evaluation after hand injury if:

• a finger does not actively flex,
• a wound is present on the hand or finger,
• grip is weakened or fingers are numb.

Do not wait for the wound to heal — inability to flex a finger is an urgent warning sign. Early intervention significantly improves the chance of full recovery.

Related content and next steps

• Doctor profile: Artur Soczka, MD, PhD
• Related service: Hand Surgery
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