Osteoarthritis is the most common form of arthritis. It typically affects the hands, knees and hips. According to the study, the progressive condition currently affects 15 percent of the global population over 30. The study found that between 1990 and 2020, cases of osteoarthritis rose to 595 million from 256 million globally, an increase of 132 percent. In Canada, the issues went up from 1.8 million to 4.1 million over the same period, according to the study's author.