Short answers, pulled from the story.
Arthritis is a general medical term for a disorder in which the smooth cartilage lining a joint is lost, leaving bone to grind on bone during movement. It causes joint pain, stiffness, and often redness, warmth, swelling, and decreased range of motion. The word comes from arthr-, meaning joint, and -itis, meaning inflammation.
Osteoarthritis is the most common form, affecting more than 3.8 percent of people, usually in weight-bearing joints such as the hips and knees. Rheumatoid arthritis is the second most common, affecting about 0.24 percent of people, and is an autoimmune disorder that often affects the hands and feet. Other types include gout, lupus, and septic arthritis.
Osteoarthritis results from cartilage breakdown due to wear and tear, with increased age being the strongest predictor, and its pain starts with activity before becoming constant. Rheumatoid arthritis is an autoimmune disorder in which the immune system attacks the joint lining, is symmetrical on both sides of the body, and is generally worse in the morning with stiffness lasting over 30 minutes. Rheumatoid arthritis usually onsets earlier in life, commonly affecting people aged 20 and above.
There is no known cure, but treatment includes resting the joint, heating or icing, weight loss, and exercise, which can be more effective than medication for knee osteoarthritis. Medications range from acetaminophen for osteoarthritis to NSAIDs and disease-modifying antirheumatic drugs for inflammatory types. Severe cases may require joint replacement surgery, known as arthroplasty, which can last 15 to 30 years.
More than 20 percent of people in the United States have a type of arthritis, and a CDC survey using 2013 to 2015 data found 54.4 million adults, or 22.7 percent, with doctor-diagnosed arthritis. It is the most common cause of disability in the United States, with a total estimated cost close to $100 billion, almost half of it from lost earnings.
Evidence of arthritis has been found in dinosaurs, and the first known traces of human arthritis date back as far as 4500 BC, including in the mummy Ötzi from around 3000 BC. In 1703, William Musgrave published De arthritide symptomatica, and Augustin Jacob Landré-Beauvais was the first to describe rheumatoid arthritis. John Charnley completed the first total hip replacement in England to treat arthritis in the 1960s.