Why does inner knee pain occur when bending the knee?

When you bend your knee, several parts—like cartilage, ligaments, and nerves—work together. Studies show that doing lots of bending can lead to tiny injuries or lesions in the knee joint. Over time, these small injuries may build up, especially if you often perform activities that put extra pressure on your knee. This can lead to arthritis, where the cartilage (the soft cushion in your joint) wears down, causing pain. One study noted that frequent bending might be linked with small spots of damage seen on imaging. Another possible cause is saphenous neuritis, which is when the saphenous nerve on the inner side of the knee gets irritated. This irritation can also feel painful when bending the knee. So, both the wearing out of the joint tissues (as seen in osteoarthritis) and nerve irritation can lead to inner knee pain when you bend your knee.