The "cracking" is caused by synovial fluid. Google it. It's the equivalent of cracking your knuckles.
I also have arthritis, but no need for replacement. (The success record is poor, anyway). I take glucosamine with chondriton every day. It may take several weeks, and the benefit is gradual. If you stop taking it, the pains return and you have to build it up again.
The usu dose is 1500/1200 3x/day. It's expensive, but you can almost always find a 2-fer. For some reason, I prefer Osteo-BiFlex. You can get extra strength tablets that you only need to take once or twice a day.