I snapped ACL and badly tore medial ligaments (in knee) around 5 years ago.(Sailing injury)
Had ACL replaced (eventually) and medial "tidied up" (as surgeon called it) Initial poor recovery with no sailing for approx 18 months.
Gradually got back to full use with loads of cycling. (Took at least 3 years from operation to get to surgeon`s quoted 80%. Now reckon its as strong as before injury.(Its better than other knee now)
I think my long recovery was probably to do with age.(Not that old but was 47 when injured) and I had a couple of falls on knee after surgery.
Its great now ; aches after hard useage but even restarted snowboarding.
Good luck. Buy a bike. (Exercises knee without impact. Be patient. It will recover !!!)
If it needs surgery get it done sooner rather than later. (Footballers get it done same week as injury !!! ,(if its needed) mine was 5 months after !!!) (Was told physio would work !!!)