Flexor Tendon Injuries

What is the Flexor Tendon?

Tendons are the bands of fibrous connective tissue that connect muscles to bone. Tendons aid in the movement of the fingers, hand and all other body parts.

Two types of tendons are present in the hand- extensor tendons and flexor tendons. Extensor tendons are on the top of the hand and help straighten the fingers. In contrast, flexor tendons are on the palm side of the hand and bend the fingers.

How are the Flexor Tendons Injured?

Deep cuts on the undersurface of the wrist, hand, or fingers can cut and injure the tendon and make it unable to bend one or more joints in a finger. When a tendon is cut, it acts like a rubber band, where the cut ends are pulled away from each other.

Flexor tendon tears may be partial or complete. If tendons are completely cut through, the finger joints will not bend on their own at all.

Impact of Flexor Tendon Injuries

A flexor tendon injury can cause various problems depending on its severity. A minor injury causes pain and inflammation, while a complete tear or cut of the tendon can render you unable to bend your finger. If untreated, these injuries can lead to long-term disability, including stiffness, pain, and loss of function. They can also cause other problems, such as a "trigger finger", where the finger gets stuck in a bent position.

Who is Most at Risk for Flexor Tendon Injuries?

Anyone can experience a flexor tendon injury, but certain people are at higher risk. These include:

• Athletes who use their hands and wrists intensively (e.g., baseball players, rock climbers, gymnasts) are at risk.
• Workers with jobs that involve repetitive hand and wrist motions or handling sharp objects.
• People with rheumatoid arthritis
  

Causes of Flexor Tendon Injuries

Any cut or laceration to the forearm, hand, or fingers can cause a flexor tendon injury. Other possible causes include:

• Damage to the tendon from a sports injury, often associated with football, rugby, and wrestling
• Stretching of the tendon where the tendon is pulled off the bone
• Jersey finger: When a player's finger catches on another player’s jersey or clothing
• Rheumatoid arthritis
• Adventurous activities such as rock climbing

What are the Symptoms of Flexor Tendon Injuries?

Symptoms of flexor tendon injuries can include:

• Pain: Pain can be present when bending or straightening the finger.
• Inability to bend finger or thumb: This is a common symptom of a serious tendon injury.
• Swelling: Swelling in the area around the injury is common.
• Tenderness: The area might be sensitive to touch.
• A gap or depression in the tendon: In severe cases, there might be an obvious physical defect where the tendon is damaged.
• Bruising: Bruising may appear around the area.

If you suspect a flexor tendon injury, seek medical attention immediately. Prompt treatment can increase the chances of regaining the full function of the affected finger or hand.

Types of Flexor Tendon Injuries

Flexor tendon injuries generally fall into a few categories:

• Lacerations or cuts: This is where the tendon has been severed or partially severed due to a sharp object.
• Strains and tears: These are often the result of overuse or sudden, extreme force. Strains are minor injuries that only stretch the tendon, while tears can be partial (only part of the tendon is damaged) or complete (the tendon is severed).
• Tendonitis: This inflammatory condition results from overuse and causes pain and limited mobility.
• Avulsions: In this injury, the tendon has been pulled away from the bone. This often happens in sports or high-impact activities.

Zones of Flexor Tendon Injuries

Flexor tendon injuries are often classified into five zones based on the location of the injury in relation to the fingers and wrist:

• Zone I: Injury involves the distal part of the finger.
• Zone II: Known as "no man's land," injuries here affect the area from the middle of the finger to the distal palmar crease.
• Zone III: This zone covers the palm area.
• Zone IV: Involves the carpal tunnel.
• Zone V: Injuries here are proximal to the carpal tunnel at the wrist and forearm level.

How are Flexor Tendon Injuries Diagnosed?

Diagnosis of a flexor tendon injury typically involves a detailed medical history and physical examination. Your doctor will look for typical signs such as an inability to bend the finger, pain, and swelling. They may also perform specific hand movements to test for tendon function.

Imaging tests such as X-rays, MRI or ultrasound can also be used to confirm the diagnosis and determine the extent of the injury.

How can Flexor Tendon Injuries be Treated?

Minor Injuries

Rest, ice, compression, and elevation (RICE) can be used for minor strains and inflammation. Over-the-counter anti-inflammatory medication may also be recommended.

Moderate to Severe Injuries

Surgery is often needed to repair a completely severed or torn tendon. A ruptured tendon cannot heal without surgery because the cut ends usually pull away from each other.

There are many options to repair a cut tendon; the type of repair depends on the type of cut. The procedure aims to restore the normal function of the joints and surrounding tissues following a tendon laceration.

Flexor tendon repair can be performed under local or general anaesthesia. The surgeon makes an incision on the skin over the injured tendon. The damaged ends of the tendon are brought together and stitched together. If the tendon injury is severe, a graft may be required. A graft is a tendon derived from other body parts, such as a foot or toe. After repairing the tendon, the incisions are closed with sutures and a dressing is placed over the surgical site. Your surgeon will place your hand in a protective splint to restrict movements.

You will be advised to start hand therapy following surgery. This is to improve the movement of the finger. Follow your surgeon’s and hand therapist’s instructions for a successful recovery.

Possible surgery complications include pain, bleeding, infection, stiffness, rupture of the repair, and damage to the surrounding nerves or blood vessels. A second surgery may be needed to release any excess scar tissue that interferes with finger movement.

What if Flexor Tendon Injuries are Untreated?

If a flexor tendon injury is left untreated, it can result in long-term complications, including chronic pain, inability to flex the affected finger(s), and loss of function. It can also lead to stiffness, scar tissue formation, and the development of deformities. Thus, early treatment is crucial to ensure the best possible recovery and restore hand function.