When it comes to efficient, pain-free running, success hinges on the knee ... Young says a twisted knee can feel like a persistent sharp pain which occurs a day or two after the initial injury ...

Movement of the hinge joints of the knees, shoulders, ankles, fingers, and toes is essential for all daily functions, from activities of daily living like bathing, getting dressed, and eating ...

You’ve had an idea. You could use a hinge? Well, it will move in the right way… Sometimes people need replacement body parts too. Like false teeth… or artificial knees - even arms and legs.