Had one. It's not fun. Incidentally, as I understand it, DBo didn't tear his ACL, which is the back ligament in the middle of the knee. Boston tore the patellar TENDON which is different from the ligament in that it's partially vascularized (gets blood and in turn can heal itself in many cases). A ligament gets no blood. It can't heal itself, so if you partially tear it, you just deal with the part that's left for good. If you completely tear the ACL, you need to go in and replace it (reattach etc.). Some people don't repair it and can build the muscles around it so much that they are strong enough to compensate, but this is unlikely and IMO unwise. The surgery that Chester will have is grueling. And the Rehab is even worse, but it is possible to completely rebuild the strength there.