Knee replacement surgery

I really think I need knee replacement surgery,  My knees are getting worse by the day and I can barely make it down my stairs most days.  I have had to cancel dates before because I couldn't walk down the stairs.  All I did yesterday was lay in bed with my leg stretch out it feel good just to relax and not have to be on them.  I am just afaird that at the age of 24 they will find me too young for a replacement.  I have to do something I am getting to the point i can't hardly walk.   I can't get my rhemy to do x-rays or mris for my knees so I am going to call around today and see if someone can look at them for me.