Mallet finger is a condition where the end of the finger is bent and does not straighten. It occurs when the extensor tendon on the back of the finger is damaged. The finger joint is a hinge-joint that allows bending and straightening of the fingers. Each finger is composed of 3 phalanges bones, joined by 2 interphalangeal joints (IP joints). The joint near the base of the finger is called the proximal IP joint or PIP joint, and the joint near the tip of the finger is called the distal IP joint or DIP joint.