Risk Factors for Arthritis. Age > 40 years Women > men ObesityPrevious joint injuryEthnic background. Osteoarthritis. Your mother, who is overweight, has pain in both knees whenever she walks too far. Her knees are stiff in the morning and hurt before it rains. The pain gets better when she rests or takes acetaminophen, ibuprofen, or naprosyn over the counter. Her knees are big, bony, and sometimes swollen, but don't get red or warm..