I would agree that it need not be mentioned, and that you can be wearing during the procedure.

Just today I had a consult w/ a surgeon about some surgery on one of my ears ... I told him I wore, and that I assumed I should not on the day of surgery. He told me it would be no problem ... only asking if the hair by my ear was my own ... which it is. So even in that close proximity to the hair, the surgeon wasn't fazed. Knee surgery should be a complete non-issue.

FWIW,
~FB