What condition are they treating, and what else is part of the rehab program?
Isolating the VMO has proven difficult to do, and there is a lot of research to back that up. While the VMO is a part of helping medial tracking issues, my point is simply that there are other things going on. The VMO issues are also usually part of overall quadriceps weakness, and you skiing could help to address that.
The knee is a 'dumb' hinge if you will, and many of it's problems come from the highly mobile joints right above and below it- the ankle and hip. You have to address what else is going on contributing to the condition other than just one hard to isolate, not very big muscle. That was all I'm saying. I'm pretty sick of seeing some rehab programs just addressing the VMO like was prevalent in the past without looking at the bigger picture. It's not enough in it's self.
Your doc is probably great. I don't know anything about your knees, and I'm not going to second guess her. I am sure she was doing other things to address your knee as well. My point was only that the VMO in it's self is generally not enough to get anything done to address tracking issues. Google it if you don't believe me.