I'll give you my 2 cents as a therapist but ultimately this decision will be up to your orthopedist and therapist. Because you are replacing the joint, once you rehab both of them you should be good to go with lifting. The reason you are bone on bone is because you have wore down the meniscus to nothing. This joint replacement replaces the ends of each bone and the meniscus. Basically, you can't hurt it outside of direct trauma or repetitive trauma. You will be advised to not do high impact activity anymore such as running.
Obviously, you are risking wearing out the replacement sooner depending on the material used (although most surgeons claim they last a lifetime now) if you go back to heavy lifting but you shouldn't have restrictions. I would still inquire about this information from your orthopedist. Good luck.