There is no evidence in the literature that consistently points to "cracking joints" being a cause of degenerative joint disease of any kind. In fact, the hypothesis that the sound came from rapidly generated bubbles of CO2 gas is still under scrutiny.
However cracking joints is a by-product of joint manipulation, and sometimes joint manipulation can exacerbate existing joint conditions. For example the major concern with chiropractic manipulation of the spine for lower back pain is that while it provides good short-term symptomatic relief, standard medical school of thought warns against it as it seems to worsen osteophyte development in the long term.
