I had the same thing abot 6 years ago, I was wfp then and on the tools every day so was very worried, although not as worrried as I would have been back in the dark, old fashioned, black and white days of ladders.

I took the doc's advice and did everything he said and I was back at work fairly soon after, steady at first but very quickly back up to speed.
It was about 2 years to full recovery for me. by that I mean it took that long to not even notice it, for a long time it was noticeble weaker than the other knee but never to the extend of being a problem.
if you follow the dcoctors advice I am sure all will go well.
Good Luck.