Replying to Broken Leg rehab

I got a compound fracture about 7 weeks ago and the doc says I should be able to ski in around 2 weeks. However he was saying that I should be careful of injuring my acl because of muscle atrophy. If you have experience with breaking your leg is there anything I can do beside physical therapy to help strengthen my acl back to its norm. Also how worried should I be about injuring my acl I figured I would take it easy for like 2 weeks back on snow and then start going back to normal.

Thanks