My legs were highly muscular when I had the injury. The surgery was in late 2013. The problem is I failed to do the physiotherapy that was suggested, the amount of muscle difference that I had to build up was huge. I built up the leg to certain amount and just made do with it because I was young and careless at the time. Now it's 2017, I ran a lot the past few weeks and my knee feels weak and not so supportive. Can I pick up by doing gym workouts and try to build back mass to match legs.