I have read 3 recent medical journal papers that say their clinic is now sometimes prescribing braces if you have slight uncorrected knee malalignment that affects your bad compartment. i.e., if your bad compartment is medial, and you are a little bowlegged (genu varum) like me, then it really is probably best that you wear a brace when going on long walks, jogging, sports, etc. In fact, a paper by Steadman (mfx inventor) seemed to suggest that they are now prescribing braces to all patients for sports, regardless of knee alignment. (Cartilage. 1(2) pp 78-86, 2010). The author of one of the other papers informed me that the usually have the patient start using a brace 3-4 months postop, once the quads are built up again to their original size. Although I've heard from one person on kneeguru that she was put in an unloader brace right when she began weightbearing...I guess there's not a consensus yet?
However, I think most doctors don't prescribe for most mfx patients, so you should ask your dr to check your alignment (via long limb x-ray or goniometer), and push for getting a brace if malaligned, like I had to. (When I brought it up, my Dr just said 'well, when i prescribed them before, almost all patients end up not wearing it because they don't like it.' Um, excuse me? I expect to at least be told about the benefits and offered the choice, thanks very much. And maybe the problem is also that you're prescribing crappy brands/models--which seems to be the case after doing some reading on this forum.) Or, if you want one even without malalignment, just bring it up and tell ur Doc that steadman is prescribing braces for everyone now. Don't feel bad about being demanding with your Doctor, they are working for you, it is your body and, if you are able and willing to become informed, you should have a say in the decision-making process. Really talk about it with them and ask them to justify their opinions / treatments.
You have to realize that an unloader brace will take some of the forces that would be absorbed by your bad compartment, and transfer those forces to your good compartment. So if you're going to do high-impact sports, your good side will get more wear than it would doing the same activity with a perfect knee. You'll have to decide if that extra potential wear to your good compartment is really worth it to you vis a vis your sport activity, as it could potentially lead to arthritis (or acute injury) in your good compartment. As for me, I think preserving my knee repair as long as possible is most important, and I'll be happy with long walks and riding my bike and swimming. Surgery (recovery) was a big pain in the A, and I'd like to avoid having to go thru it again, as long as possible at least.