Tendons are tissues that connect muscles to bone so that joints can bend or straighten. The flexor muscles that move your fingers and thumb are located in your forearm, above your wrist. Long tendons extend from the flexor muscles through the wrist and attach to the small bones of your fingers and thumb.
Each finger has two tendons; the thumb has one tendon. The tendons run along the palm side of the fingers and are very close to the surface of the skin, particularly where the skin folds as you bend your fingers. The longer tendon (flexor digitorum profundus or FDP) attaches to the last bone of the finger and bends the tip; the shorter tendon (flexor digitorum sublimis or FDS) bends the middle joint of the finger.
If you tear (rupture) or cut (sever) the tendon anywhere along its route, at the wrist, in the palm of the hand, or along the finger, you may be unable to bend your finger. If you injure the FDS tendon, you may still be able to bend the finger, but not completely, and bending the finger will be painful.
Tendons are stretched tightly as they connect the muscle to the bone. If the tendon tears, the end connected to the muscle will be pulled back in toward the palm. Because the tendon can’t heal unless the ends are touching, a severed tendon must be sewn back together again (a surgical repair).
Types of injuries
Most often the flexor tendons are damaged by a cut. Because the nerves to the fingers are also very close to the tendons, a cut may damage them as well, resulting in a feeling of numbness on one or both sides of the finger.
Athletic injuries are also common, usually in football, wrestling or rugby. One player grabs another’s jersey, and a finger (usually the ring finger) gets caught and pulled. This type of injury is so common, it even has a name: “jersey finger.” You can also strain or rupture the tendon while rock climbing.
People with rheumatoid arthritis may experience a spontaneous rupture of the flexor tendons. You may notice that the finger no longer bends, but cannot recall when you lost the ability to bend it.
Signs and symptoms
- An inability to bend one or more joints of the finger
- Pain when you bend your finger
- An open injury, such as a cut, on the palm side of the hand, particularly in the joint area where the skin folds as the finger bends
- Mild swelling over the joint closest to your fingertip
- Tenderness along the finger on the palm side of the hand
Diagnosing your injury
See your physician whenever you injure your fingers, especially if you “jam” the finger and notice that you cannot bend or straighten the tip. For immediate first aid, apply ice and compression to slow the flow of blood to the damaged site.
Your doctor will ask you to bend and straighten the fingers and may apply resistance to test the strength of the fingers. Your doctor may also test the sensation and blood flow to your fingers to see if any nerves or blood vessels were also injured. You may need to get an X-ray to see if there is any damage to the bone; if you have an open wound, you may need a tetanus shot or antibiotics.
Your doctor may first clean and treat any superficial wounds and put your hand in a splint. Flexor tendon injuries require surgical repair and it’s best to have the surgery as soon as possible after the injury. The hand surgeon will sew the tendon together using special stitches on both the inside and outside of the tendon. However, it can take up to two months before the repair is healed and strong enough to use your hand without protection. It may take another month or so before you can use your hand with any force.
In the meantime, you will need to wear a splint and see a physical therapist. The therapist will give you special exercises to perform. Follow your doctor’s and your therapist’s instructions carefully to ensure the best possible result.
Even after surgery, you may experience some stiffness in your finger. However, it will be considerably less than if you did not have the surgery.
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