Arthritis (in a nutshell) is inflammation and swelling of the cartilage and lining of the joints, generally associated with increase in the fluid in the joints. There are 33 joints in each foot, and can be affected by arthritis.
Put simply, a podiatrist is an allied health professional who diagnose and treat conditions of the foot, ankle, and related structures of the leg. Why do we call podiatrists the first responders for vascular disease? Because first symptoms appear in your feet.