150 + types arthriti. There are over 150 types of arthritis so these differ and these symptoms can be different. The symptoms come from swelling, inside the knee, rubbing of bones and cartilage, inflammatory crystals, torn menisci, joint mice (debris) etc. Each person is different and your evaluation will look at these things to try to help make the diagnosis and develop your therapy program.
See below. When joints become inflamed from arthritis, the nerves that supply the joints become sensitized by the inflammation. These nerves send pain signals to the spinal cord and brain and you experience pain. Most treatments for arthritis seek to decrease the inflammation which in turn calms the nerves down.