You ever had that and the knee arthroscopy to remove them?
How did it go?
How was recovery?
depends on what has to be cut to get to the object. Most foreign objects are pieces of bone that pulled off the bone from a ligament injury, Body then calcifies over it to smooth it out. Normally knee clean out is cutting away/smoothing out the arthritis/cartridge, removing bone spurs, tighening or releasing ligaments etc.
here is a skittle sized peice of bone taken out if my ankle, it was probably originally a piece of bone that came off the big bone when I sprained/tore a ligament