Flexor Tendon Injuries

Tendons are cord-like structures that connect muscles to bone. In the hand, the flexor tendon attaches muscles in the forearm to the bones in the fingers. When the muscles contract, tendons bend the fingers.

Each finger has two flexor tendons – one bends the middle joint, the other bends both the middle and fingertip joints. The thumb has one flexor tendon to bend the tip.

Causes of Flexor Tendon Injuries

The most common cause of a flexor tendon injury is a deep cut to the palm or the finger(s). When cut, the tendon acts like a rubber band, and the end pulls away from one another. When this happens it becomes impossible to bend your finger(s).

If a tendon is partially cut, the finger may still bend a little. This usually painful and difficult.

The finger nerves are close to the tendons, and a deep cut may injure them as well. This will cause numbness on one or both sides of the affected finger. 

Sometimes, the flexor tendon may tear or pull away from the bone. In sports, a player may grab another’s jersey, the finger may get caught in the fabric causing the flexor tendon to tear. This injury is called a “jersey finger”. People with advanced rheumatoid arthritis may experience a spontaneous flexor tendon rupture.

Signs and symptoms of an Flexor Tendon Injuries may include:
  • Inability to bend the finger normally
  • Pain when bending
  • Minor swelling in the injured area
  • Tenderness on underside of the finger
  • Open wound or cut on the palm side of the hand or finger

Certified hand therapists can custom fit a splint which, depending on the severity of the injury, may be used without surgery, or following surgery to allow the tendon to repair to fully heal.
At your first hand therapy appointment, your therapist will remove your post-op dressing and make a custom splint. This splint will be worn full-time for six weeks.


Tendons will not heal unless the two ends are closely touching. The only effective treatment for a flexor tendon injury is to surgically repair the tendon(s) by sewing the cut ends together. Your hand surgeon will locate the ends of the tendon and stitch them back together. If the nerve has also been cut, it will be repaired at the same time.

Hand Therapy

Certified Hand Therapists work closely with doctors to create a customized therapy and rehabilitation program to restore function. Your therapist will
also instruct you in a very strict home exercise program, teach you scar management techniques, and help you progress through the post-operative rehabilitation protocol ordered by your hand surgeon. Most people need 1-2 hand therapy appointments per week for 8-12 weeks.
Consistent follow-through with your home exercise program is a vital part of your recovery process and will help ensure the best possible outcomes. Your full recovery and safe return to your activities depends on how carefully you follow your therapy instructions.

Diagram of Flexor Tendons in hand, TRIA Orthopaedic Center/Acute Injur Clinic

The tendons of the hand run from the flexor muscles in the elbow and forearm to the bones of the fingers

Flexor Tendon in hand, TRIA Orthopaedic Center/Acute Injur Clinic
When flexor tendons are completely cut the finger cannot be bent
Flexor Tendon Injury, hand injury, TRIA Orthopaedic Center/Acute Injury Clinic
After surgery the area of the injured tendon must be protected from movement

Courtesy of American Society for Surgery of the Hand