Over the three years before I had the other hip
replaced, I developed problems in
my left foot, opposite knee, and lower back.
Having said that, RA can have many different triggers. A common infection can trigger the immune system to start attacking the body - no one knows why. Stress or an injury, basically anything that prompts an immune system response can potentially trigger RA or another autoimmune disease. It can run in families, or appear apparently out of nowhere.