A neuroma in the ball of the foot area is more commonly described as a callus that has developed around a nerve between two metatarsal bones. This comes from an improper movement in the foot as you go through your gait cycle. It can be caused by shoes that are too tight in the ball of the foot area but this is not always the case. If the heel bone is hyper mobile and allows the medial (main) arch and the transverse (metatarsal) arch to collapse during the gait cycle, it can cause sheering in the forefoot area while you are standing and while walking. This sheering (rubbing) can cause at least two metatarsal bones to rub together creating the callus around the nerves that are between the bones. Once the callus develops, it becomes hard and presses on the nerve causing it to hurt.
The knee is the largest joint in the body. The upper and lower bones of the knee are separated by two discs (menisci). The upper leg bone (femur) and the lower leg bones (tibia and fibula) are connected by ligaments, tendons, and muscles. The surface of the bones inside the knee joint is covered by articular cartilage, which absorbs shock and provides a smooth, gliding surface for joint movement.