An elevated CRP level can indicate infection but it may just as easily indicate excessive swelling and inflammation. So don't panic until you've seen the doctor. He may want to do some additional tests such as a nuclear bone scan and if there are any signs in that, progress on to aspirate some fluid from your knee and send that to the lab for analysis. You really won't know for sure until then because neither of the first two give definitive results right off. And if the surgeon says it does, then he's guessing!