Two key caveats: 40% of people said their arthritis got better with the placebo treatment, while 70% got better with the radiation. Yes, that's clearly a difference, but it also means that 40% of people don't need to expose themselves to the side effects of radiation in order to get relief from their arthritis. Second, the realy number of people who don't need radiation is actually higher, because this study limited the use of NSAIDs like ibuprofen (Advil) or naproxen, which would probably have helped a lot of the other people. Granted, for people who can't take NSAIDs because of kidney disease or something, maybe this will be an option in the future, but I really want to see the long-term safety data before I go irradiating everyone's knees.