Rob Van Dam underwent reconstructive knee surgery on January 27th. The procedure was done by Dr. James Andrews in Birmingham Alabama.
The surgery repaired a torn ACL, and RVD is expected to miss about six months.
Interesting, the surgery comes at a time when RVD was reportedly out of favor with WWE management because he skipped the Smackdown tour to Iraq. Rather than being able to punish RVD with a reduced push, some believe he chose to have major surgery now rather than later.
HHH has been vocal in recent media appearances pointing out that RVD had something missing to become a main eventer, so perhaps that is how WWE is exacting punishment on Van Dam.
credit: Dave Meltzer Wrestling Observer Newsletter