What are some problems associated for not getting treated for torn acl?

Many problems. Hi, aside from the problems that have been addressed with regards to worsening knee disease, consider what other health problems may arise. Specifically, if your knee is painful, you may end up favoring your knee and causing problems in other joints and muscles from altered biomechanics. Also, a big problem could be worsened overall health from relative inactivity. See your doctor and good luck.
Instability. Repeated instability episodes can cause further cartilage or meniscal injury in the knee.