This is a quick but informative video which I found on YouTube about one of the myths what causes OA. It answers the question:
Is Cracking Your Knuckles One of the Causes OA?
As the video explains it is only gas inside the joint that pops (similar to opening a fizzy drink) that makes the popping noise and that knuckle cracking was not one of the causes of OA. There was a big study done recently which confirmed this opinion.
However I admit to finding this surprising. As the video says chronic cracking does cause damage to the ligaments and makes the joint hyper-mobile (or lax and loose) which weakens the joint. This is effectively a repetitive stress injury and research shows this is one of the causes of OA as I discuss here.
So even though there may not be research specific that cracking knuckles I do suggest it is NOT a healthy thing to do!