Extensor Tendon Injuries


Extensor tendons are just under the skin. They lie next to the bone on the back of the hands and fingers and straighten the wrist, fingers and thumb (Figure 1). They can be injured by a minor cut or jamming a finger, which may cause the thin tendons to rip from their attachment to bone. If not treated, it may be hard to straighten one or more joints. 

Common Extensor Tendon Injuries

  • Mallet Finger refers to a drooping end-joint of a finger. This happens when an extensor tendon has been cut or torn from the bone (Figure 2). It is common when a ball or other object strikes the tip of the finger or thumb and forcibly bends it.
  • Boutonni√®re Deformity describes the bent-down (flexed) position of the middle joint of the finger. Boutonniere can happen from a cut or tear of the extensor tendon (Figure 3).
  • Cuts on the back of the hand can injure the extensor tendons. This can make it difficult to straighten your fingers.