Flexor Tendon Injury

What is a Flexor Tendon Injury?

A flexor tendon injury occurs within the area of the palm side of the hand or forearm. By medical definition, flexion means to bend; therefore, with a flexor injury, it is the flexor muscles and tendons that when injured prevents us from bending our wrist or fingers. So, what does this mean?

Our hands are complex in design; we have many bones, ligaments, muscles, tendons, and nerves that make up the structure and function of our hands. All structures are intricately designed to coordinate together to provide sensation and movement of our hands and fingers.

We have approximately 29 bones and ligaments in each of our hands. The bones provide structure while the ligaments attached to bone to bone to form a joint. Ligaments are tough fibrous tissue that keeps the bones stabilized, or together, throughout the movement.

Within the hand, the palm area of our hand has five metacarpal bones extending to the 1st joint of each finger, or what is known as our knuckles. Each finger has three phalanx (finger) bones except the thumb only has two phalanx bones. The metacarpophalangeal joint (MCP) is considered our knuckle bones. The next joint is the proximal interphalangeal joint (PIP). The most distal joint is called the distal interphalangeal joint (DIP).

Our thumbs are designed a little differently. At the base of the wrist and thumb is the carpometacarpal joint (CMC). The next joint is the “knuckle” of our thumb which is called the metacarpophalangeal joint (MP). And finally, the interphalangeal joint (IP) is the tip of the thumb joint.

Understanding the names of the joints within our hands is important as all medical providers use these terms to describe and navigate the hand. It also is important to know each joint and phalanx has ligaments keeping them stable as well as tendons to assist with movements.

Tendons act like a pulley system attaching the muscle to a bone. Most of our hand movements come from muscles within forearms, not within the hand itself. Collectively the muscles and tendons work together to allow for flexion (bending) or extension (straightening) movements of our wrists or fingers.

Specifically related to the flexors of our hands, this allows us to pinch, grasp, or make a fist with our hands. We have five major muscles and tendons within each of our forearms and hands that help us with flexion movements. The five muscles are:

  • Flexor Digitorum Profundus (FDP)-flexes the DIP joint; assist with flexing the PIP and MCP
  • Flexor Digitorum Superficialis (FDS)-flexes the PIP joint; assists with flexing the MCP
  • Flexor Pollicis Longus (FPL)-within the carpal tunnel area
  • Flexor Carpi Radialis (FCR)-flexes the wrist
  • Flexor Carpi Ulnaris (FCU)-flexes the wrist

In addition to bones, ligaments, muscles, and tendons, nerves also play an important role in the movement of our hands. Nerves are the pathway of how the brain communicates with the rest of the body. We have many nerves within our hands; however, there are three primary nerves-ulnar, radial, and median nerves.

Each nerve innervates with a specific part of the hand assisting with movement and sensation. The radial nerve assists with the extension of the wrist and fingers. The ulnar and median nerves assist with the flexion movements of the hand and fingers. The ulnar nerve controls the palm, little, and ring fingers whereas the median nerve controls the palm, thumb, 1st and 2nd fingers.

What causes a flexor tendon injury?

Often a flexor tendon injury is caused by a laceration or cut. With a cut to a tendon, there typically is damage to surrounding tissues as well, like the muscles, ligaments or nerves. With a severe cut to a flexor tendon, you may lose the ability to flex the wrist, finger, or joint; however, with a partial cut, you may still have some ability to flex, but it is limited.

In rare situations, a tendon may rupture, or pull away from the bone, which is rare, but if it does happen, you will lose the ability to flex where the tendon avulsion occurred (wrist, finger, joint). One example of this is called the “Jersey Fingers,” which is when there is too much force during flexion that the strained tendon pulls away from the bone. Which commonly occurs in sports like football when grabbing a sports jersey. When a finger gets caught up and twisted into the jersey, the forces of pulling away between the two players is so great; it causes the tendon to tear.

Symptoms of Flexor Tendon Injury

Whether you cut yourself or a traumatic event occurred to the volar (palm) side of your arm or hand, if a flexor tendon was affected, you may experience the following symptoms:

  • Inability to flex the finger (depends on where the injury occurred)
  • Loss of sensation (if nerve was affected)
  • Open wound, bleeding
  • Pain with bending
  • Tenderness

How is a flexor tendon diagnosed?

Most flexor tendon injuries are due to lacerations or trauma; therefore, if you suspect an injury because you cannot flex (bend) a finger, or fingers, it is always best to take precaution and visit a health care provider immediately.

In the most severe cases, a physician will need to assess if there is more damage than just the tendon. With a laceration, there is likely to be nerve, artery, or even ligament damage as well. If you are not bleeding profusely, your physician will ask you to bend your fingers and make a clawed fist, which is the easiest way to determine if you there is any flexor tendon injury.

Treatment of Flexor Tendon Injury

Not all flexor tendon injuries need surgery, but most do. If you are having difficulty, or simply cannot, flex a finger after an injury, it is recommended you seek medical attention. If you have a minor injury, a physical therapist specializing in the hand can see you without a physician’s order; however, if you have cut yourself with a severe open wound and possible severe damage, seek immediate medical attention from your doctor.

With minor injury cases, your physical or occupational therapist (PT or OT) will customize a splint to immobilize the finger(s) preventing you from using the tendon. This immobilization will allow time for the tendon to heal. Once the healing has occurred, which takes several weeks, a progressive strengthens, and range of motion regimen is started.

With most flexor tendon injuries, surgery is indicated. Before determining if you are a surgical candidate, your physician will thoroughly assess the injury. The unfortunate part of this injury, despite being surgically repaired, most do not regain full range of motion back.

The factors that play into a full recovery include:

  • Injury to a nerve
  • The length of time from the injury to surgery
  • How much structural damage was done (e.g. full or partial cut)
  • Prone to developing scar tissue
  • Lack of participation in rehabilitation post-surgery

Keep in mind tendon flexor injuries are serious. Most need surgical intervention, and most take months to heal. Unfortunately, with this type of injury, there is no short-cut. Get the medical help you need and complete the full course of care to improve your odds for a full recovery.

Next Steps

As a consumer of health care, you have a choice in finding the right provider for you. If this is a non-emergency injury, do your homework and search for a health care provider with excellent outcomes, great customer reviews, and can provide you the care you need for a reasonable cost.

Most states have direct access to a physical therapist, meaning you can go directly to a physical therapist without a physician order. To determine if your state has direct access, please visit the American Physical Therapy Association’s website Physical Therapy Direct Access By State.

If you are a surgical candidate, once you’ve had surgery, it is recommended you do your homework then to find the highest qualified hand PT or OT in your area. You can find a highly qualified PT or OT in your area by clicking on Find A Clinic. This link will help you find a PT or OT that has top national rankings for treating hand injuries.

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