Hinge joints are joints that can only move in one direction, such as the elbow, knuckle and knee joints in the body are hinge joints.
Hinge joints can only do flexion and extension and cannot rotate, i.e., they only allow limited movement back and forth.
For example, the joints at the elbow only allow the forearm to bend forward, not backward; the joints at the knuckles of the fingers only allow the fingers to bend toward the palm of the hand, not toward the back of the hand; and the joints at the knee only allow the calf to bend backward, not forward.
The hinge joints in the human body connect the two bones closely together with the help of muscles and ligaments, so that they work perfectly with each other to accomplish some flexion and extension movements to help us carry out our daily life and work.