I done my ligaments 25 years ago when I had a promising football career ahead of me they tried to build up all the muscles around the knee to take the part of the ligament but it didn't work . So I had to go under the knife to have the ligament reattached now back then it was a huge operation and I was in plaster for 6 months . But today I believe the same op is key hole . If it is totally detached you may need to have an op but as the posts above say a scan is the best way to find out the damage . On an up note although is was the end of top class football I did get back to playing at a decent level , and I cycle with no problems . Hope it's not to serious