That wrap thing is probably just to stabilize it. IN the interview, Venus said they used ice. Plus "... ice, more ice, ice, ice, more and followed that up with ice." She laughed when she said it, but yougot the feeling this wasn't her favorite part of the Open.
The knee rap thing is to neutralize the pain. Its made of synthetic material that heats up the knee or the sertain place where you put it. Rememebr last year hingis has that long sleeve/short sleeve top on. That was for her serve, and mainly every hit to keep her swinging arm warmed up so she could hit more accurately and a bit more stonger. Ddint work that well though!