Having just turned 38 in July, I am now just past 2 years since I had MFX on both knees (lateral femoral condyles on each). I've read the success rate for MFX is about 50%, and I would say that is pretty close the case with me. My left knee has responded exceptionally well (pain almost entirely gone) whereas my right knee is only mildly better. I have now returned to playing basketball on a somewhat regular basis. I manage my pain and swelling through the use of Advil and lots of ice.
However, I will say another thing that seems to help me immensely is the continued and ongoing strengthening of the muscles which surround and support my knee(s). Quads, hamstrings, calves, glutes, as well as core exercises, all play a part in not only supporting your joints but also maintaining proper body mechanics. Looking back to when my knee issues first began (around age 30) I realize muscle imbalance was probably to blame (I returned to sports after a 3 month layoff after breaking my left foot with no rehab). Once the bone in my foot was deemed healed, I was quick to get back into sports (basketball and softball). In a hurry to get my conditioning back, I just jumped back into playing as often as I could without strengthening the muscle groups I mentioned above. As a result, my joints took a pounding as the muscles were not yet firing properly to absorb much of the shock as they are intended to. But I ignored the pain and "toughed it out". Blah, blah, blah, now while also trying to avoid/delay knee replacement my OS says I will eventually need, I continue strength training exercises which, for me, help decrease the pain and improve movement. In fact, there was a point 3-4 months post left knee surgery, where I was still experiencing pain equal to or worse than I had before the surgery. I feared it was a complete failure, but I began strength training and within a week noticed vast improvement and has only improved. My right knee felt really good for a while but my stubbornness to continue playing sports has caused this one to regress somewhat.
Good luck to you.