If you are injured so badly that medical staff will see your knickers when you go to hospital, the last thing they look at is the state of them. I've had to cut a few pairs off and was more worried about getting sued for damaging personal property without permission. SO as my mum was a nurse too can't understand why she always told us that too.
You may well soil yourself with shock so sod the new knickers.
Personally I couldn't care less cause I'm a boarder so I'll probably be the one running you down Hee hee