as for suitable risk assesment on knee pads , i can tell you that i have never been comfortable wearing them as it causes me low back pain, reasons is that it alters my stance when kneeing , i know it may only be by 25-50mm from the floor but causes more problems with me, no one is the same and if you have never used them and dont have a problem then it should not be forced on to you by anyone,
I think its a issue for my doctor now and maybe legal,