Solid feet are also called flat feet, which are most commonly caused by congenital or hereditary factors; there are also some people with this condition because of fractures in the feet later in life. There are several disadvantages as follows: 1. It can reduce the athletic ability, because the arch of the foot disappears, running or bouncing loses the elasticity of the arch, and the athletic ability of running and bouncing is a little worse than normal. 2. It can cause pain in the foot, commonly known as aseptic inflammation, because the long time imbalance of the force on the foot can easily cause the tarsal bone of the foot or the plantar fascia of the foot to be damaged by frequent strain. 3. Chronic aseptic inflammation may cause valgus deformity of the ankle joint.