Sit-ups...in bed?

[MissLiss4u]

Okay, so we all know I have a bad knee. And I have to be very careful with what I do. I bought some weights that I can use with my arms...but I want to work my gut/butt and legs too. So... I can't do normal sit-ups on the ground, but while I was laying in bed last night I wondered if I where to sit on the edge of my bed with my feet hanging off at the knees, lay down and sit up, could that work too? Even if I had to do twice as many to equal one sit up, could it work?

I don't know much about all this stuff, so your imput would be awesome! Thank you!

[liv]

Can you do crunches? Usually one lay on a mat with bent knees and then lift head and shoulder blades up off the ground while crunching stomach muscles.
Most people who do situps do not target stomach much but use mostly the hip so sit-ups are often rather useless as abs exercise.