This is my non-scientific or medical opinion, but what i have seen with people with arthritis is that it comes in different form likes you mentioned. I think like most diseases there is environmental and genetic aspects as to what could predispose you to having it later in life, both seem to have similar treatment which does not remove it. Think of it like any other major injury, you are never going to un-herniate a disk in your spine, you can only manage the effects and through proper planning could minimize how often pain is felt and your chance to get another one. If i recall correct from high school health is that arthritis caused by environmental aspects is due to repetitive stress injuries that damage cartilage wearing it away and that the pain comes from bone on bone contact, a similar thing would happen if it was genetics or disease except it is due to no fault of your own or a combo of both. The treatment for most forms(again non medical) is to keep the joint moving through a healthy range or motion and that limiting ROM could cause more damage, i think how it would be addressed it moving through what the patient would be comfortable and slowly increasing the ROM to what can be done pain free. Basically if the patient could only flex their finger 70 degrees without pain, but 80 degrees would cause the patient a ton of pain the goal would be to build tolerance and capacity between those ranges in hopes that the upper threshold of pain would be increased to say 85 degrees and working up from there.