@DianaJ ... I can certainly understand your concerns based on what you've been reading and hearing about the Aesculap implant. I really want to caution you about trying to do a lot of internet research on something like this as there is so much misinformation out there!
The Aesculap knee implant is a good one and it has been successfully used in many, many patients. There have been no recalls of their products. What you will see if you do internet research is a bunch of official looking informational websites that are produced by law firms in an effort to get clients who are having problems with their knees. You need to put your trust in medical professionals and not lawyers.
While I'm sure your allergist means well, I'm not sure where he or she is getting the information that having a TKR revision causes infection, shortening of the leg, and a very difficult recovery. There is, of course, the normal risk (very low) of infection as there is with any invasive procedure. A revision does not shorten your leg. And recovery is pretty much the same as with a primary TKR. We see a lot of revision patients here on BoneSmart for various reasons and the things you are fearful of just don't happen.
What is important if your current implant is loose is that you have it revised. Your knee will not get better and, in fact, will likely worsen. It is possible to do additional bone damage if you try to walk around on an implant that is moving around. That can make revision surgery more complex when you finally decide to have one done.
I suggest that you get at least two more opinions on your knee from experienced revision surgeons. Here are a couple of surgeons you might consider:
Dr. Michael S. Bradford, MD
Nevada Orthopedic and Spine Center
Las Vegas, NV
702-258-3773
Dr. Russell T. Nevins, MD
Desert Orthopedic Center
Las Vegas, NV
702-731-4088
I would be curious to know who your current surgeon is if you wouldn't mind sharing that information. Whoever you talk to, be sure to ask how many revisions they perform each year. You want experience. Ask about the different implant options and your concerns about the bone cement sensitivity.
You don't need to rush into having additional surgery. But it is important to get opinions by medical professionals who know how to help you.
If you want to read about other BoneSmarties who have dealt with metal allergies,
here is a search of the forum using "Metal Allergy" that gives you a list of threads.