My wife had a single knee replacement in November 2017. Walking was nigh on impossible up to then, and she had developed a noticeable limp over the years before the replacement. Since then walking is almost pain free, although prolonged hard surfaces can be tiring, and the limp has all but disappeared. She continues to do exercises daily, after the physio ended, but has never gained the full 90 degree bend so steep stairs can be slow. As others have commented while you retain your original kneecap you are advised not to kneel and many find this painful. However we know of others who after the initial painful bit post-op who still climb ladders and have a cracking golf swing! It will take grit and determination on your behalf, but most likely to be well worth the obtained comfort and new-found mobility, and many years happy exploring in the caravan! The very best of luck to you!