Push/ Pull a prowler. Not sure how your knees wold respond but people even do it for rehab purposes, myself included and works like magic. Perhaps over time you can go heavier and i believe you can build serious muscle & endurance.
Be a deadlift focuser.
Don't get stuck on the doc's opinions as well, people do come through things. Light squats, even bodyweight is a good idea to start. Also give Band TKE Extensions a try, they did wonders for me too.