It is called osteoarthritis. Osteoarthritis is the most common form of arthritis. It occurs when the protective cartilage on the ends of your bones deteriorates. over time. Symptoms include pain, tenderness, stiffness of joints, inflexibility and grating in joints. Statistics show that as of 2012, osteoarthritis affected 52.5 million people in the United States and approximately 50% of whom were 65 years or older.