Orthopedic surgeons aren't certified in any of the individual surgical techniques that they do. When new methods come out, each surgeon must get the training and practice needed before operating on patients.
Right now researchers suggest the new minimally-invasive (MI) method of joint replacement should only be done by some surgeons. They should have a high-volume arthroplasty practice. This means they do a lot of joint replacements.
The best results reported have come from high-volume total joint centers. Not all patients are selected for this procedure. Surgeons who choose patients carefully tend to have better results. Some might say it's more important that the patients are "certified" than the surgeons.
Your best bet is to find a center that focuses just on joint replacement. Ask how many minimally-invasive knee replacements the surgeon has done before making your final choice.