Flexor Tendon Injury
Damage to the tendons that bend the fingers and thumb
Quick Facts
- Type: Hand and wrist tendon injury
- Location: Palm side of the hand, fingers, and wrist
- Common cause: Deep cuts; forceful gripping injuries
- Treatment: Usually surgical repair plus hand therapy
Overview
Flexor tendons are the cords on the palm side of the hand that connect the forearm muscles to the finger and thumb bones. When the muscles contract, these tendons pull the fingers into a bent position, allowing you to grip and grasp. The tendons run through narrow tunnels (tendon sheaths) and lie close to nerves and blood vessels, so an injury here can affect several structures at once.
A flexor tendon injury most often happens when a deep cut crosses the palm or the palm side of a finger and severs the tendon. It can also occur when a fingertip is forcibly straightened while the muscle is gripping hard, which can pull the tendon off the bone, an injury known as jersey finger. Because a cut tendon does not heal back together on its own and the ends tend to pull apart, flexor tendon injuries usually require surgery followed by carefully supervised hand therapy to recover good movement.
Symptoms
The main sign of a flexor tendon injury is being unable to bend one or more finger joints. Symptoms often appear right after a cut or forceful gripping injury.
- Inability to bend a finger or thumb at one or more joints
- Pain when trying to flex the finger against resistance
- A cut or wound on the palm side of the hand or finger
- Tenderness and swelling along the finger
- Numbness in the finger if a nearby nerve is also cut
An injured finger often rests in a slightly straighter position than its neighbors because the pulling action of the tendon is lost. Loss of sensation is an important warning sign that a digital nerve may also be involved.
Causes
Flexor tendon injuries usually result from trauma to the palm side of the hand:
- Deep cuts: Knives, glass, sharp metal, and similar objects can slice through the tendon, sometimes along with nerves and arteries.
- Sports avulsion (jersey finger): Grabbing an opponent's jersey or another object while the finger is forced straight can rip the tendon off the bone, often at the ring finger.
- Crush and saw injuries: Industrial accidents and power tools can tear or sever tendons.
- Disease-related rupture: Conditions such as rheumatoid arthritis can weaken a tendon so it ruptures with little force.
Risk Factors
- Work involving knives, glass, or power tools
- Contact and grip-intensive sports such as football and rugby
- Rheumatoid arthritis or other inflammatory joint disease
- Previous hand injury
- Activities with a high risk of deep palm or finger lacerations
Diagnosis
A clinician diagnoses a flexor tendon injury by testing the hand and examining any wound. Each finger has two flexor tendons, and they are tested separately to find out which is involved.
- Physical examination: Asking the person to bend each finger joint individually and testing grip and sensation.
- Sensation testing: Checking feeling in the finger, since cut tendons often accompany cut nerves.
- X-rays: Looking for a fracture or a small bone fragment avulsed with the tendon.
- Wound exploration: Direct inspection of the tendon, often in the operating room, to assess the extent of the tear.
Treatment
Most flexor tendon injuries need surgery because the cut ends pull apart and will not rejoin on their own. The goal is to repair the tendon and restore smooth gliding through its sheath.
- Surgical repair: A hand surgeon stitches the tendon ends together, ideally within a couple of weeks of injury, and repairs any cut nerves or vessels.
- Wound care: Lacerations are cleaned, and antibiotics may be given to reduce infection risk.
- Hand therapy: A structured program of protected movement begins soon after surgery to prevent the tendon from sticking down and to rebuild motion and strength.
- Splinting: A custom splint protects the repair during early healing.
Recovery takes time and effort; full strength and motion may not return for two to three months or more, and following the therapy plan closely is essential to a good result.
Prevention
- Use cut-resistant gloves and safe technique with knives and power tools
- Keep guards in place on saws and machinery
- Handle glass and sharp metal carefully
- Seek prompt care for any deep palm or finger wound
- Manage underlying conditions such as rheumatoid arthritis that weaken tendons
When to See a Doctor
Seek prompt medical care if you cannot bend a finger after a cut or injury, if a finger goes numb, or if a deep wound crosses the palm side of the hand or fingers. Go to urgent or emergency care for a wound that will not stop bleeding, a finger that looks pale or cold (which can mean a cut artery), or signs of infection such as spreading redness, pus, or fever. Early evaluation matters because flexor tendon repairs work best when done soon after the injury.
Frequently Asked Questions
Do flexor tendon injuries need surgery?
Most do. Because the cut ends of a flexor tendon retract and will not heal back together on their own, surgical repair is usually required. Surgery is most successful when performed within a couple of weeks of the injury, so prompt evaluation is important.
What is jersey finger?
Jersey finger is a flexor tendon injury in which the tendon is pulled off the fingertip bone, often when a player grabs an opponent's jersey and the finger is forced straight while gripping. It most commonly affects the ring finger and usually needs surgical repair.
How long is recovery after flexor tendon repair?
Healing takes time. The tendon needs several weeks to bond, and a guided hand therapy program follows to rebuild motion and strength. Most people regain useful function over two to three months, though full recovery can take longer.
Why is hand therapy so important after this injury?
After repair, a flexor tendon can stick to surrounding tissue and become stiff. Carefully timed, protected movement guided by a hand therapist keeps the tendon gliding while it heals, which is essential to regain finger bending. Skipping therapy often leads to a poor result.
Can a flexor tendon injury be an emergency?
It can be. A deep palm or finger wound may also cut nerves and arteries. Seek urgent care if bleeding will not stop, the finger is numb, or the finger looks pale or cold, since these point to nerve or blood vessel injury that needs prompt treatment.
References
- American Society for Surgery of the Hand (ASSH). Flexor Tendon Injuries.
- American Academy of Orthopaedic Surgeons (AAOS). Hand and finger injuries.
- MedlinePlus, U.S. National Library of Medicine. Tendon injury.
- OrthoInfo, American Academy of Orthopaedic Surgeons.