When muscles contract, tendons pull on the bones, allowing movement to occur. In the hand, the muscles that move the fingers and thumb are found in the forearm. Tendons run from the forearm's muscles through the wrist and into the hand, where they attach to the small bones of the fingers and thumb. The hand has tendons on both its top and bottom (palm). The ones on top, the extensor tendons, straighten the fingers. The ones on the bottom, the flexor tendons, bend the fingers. Each finger has two flexor tendons; the thumb has one. Because they are stretched tightly as they connect muscle to bone, tears or cuts to flexor tendons can cause them to completely separate, making it impossible to bend the affected fingers.
Signs of a Flexor Tendon Tear
A flexor tendon tear can be caused by a deep cut to the palm side of the fingers, wrist, hand or forearm. It can also be the result of a sports-related injury. Certain sports, including wrestling, football and rock-climbing, can force the tendon to rip away from the bone. Signs of a flexor tendon tear or cut include the following:
- Inability to bend one or more finger or thumb joints
- Pain when bending the finger or thumb
- Fingertip numbness
- Cut/injury on the hand's palm side (usually near bend in finger/thumb)
- Finger tenderness on the hand's palm side
There are also health conditions that weaken flexor tendons, making them more likely to tear. A person with only a partial tear to a flexor tendon may still be able to bend the affected finger, albeit not completely.
Treatment for a Flexor Tendon Tear
Only a partially torn flexor tendon, in which the ends of the tendon are still touching, can heal on its own; a splint is worn to promote healing. For complete tears, surgery, in which the torn ends of the tendon are sewn together, is required. A splint is worn after surgery, sometimes for up to two months, in order for the wrist to heal properly. In both cases, physical therapy is prescribed in order keep the hand functioning properly.