Hi @mima25au and welcome. You'll see that I moved your post to a similar discussion so that you can connect with members with similar situations.
When you say he may have to remove the whole thing, do you mean your leg? Have you sought out a second opinion?

If it's not an infection, what? I'm sure you were checked for bone cancer.
Did you have a blood test before surgery to check for allergies to the implant components? Medicare pays over for the $10,000.00 of dollars for the implant surgery but not for the $600.00 blood test for the metals and bone cement. Who make up rules like this? If you are allergic you must have the implant removed because not only will it raise inflamation in the implant area, but raise the histamines thoughout your body thus raising inflamation leading to other diseases like eczema and various other auto immune diseases.
Talk to your orthopedic surgeon and an allergist about this idea as being a cause.
If the ortho disputes metal allergies I will gladly send you a copy of my blood report from a lab in IL which identified my metal allergies and rated each based on teh severity, 2 were moderate and 3 were mild. I was not allergic to titanium, but my ortho said even titanium is not pure, it has traces of these others metals in them and thus I would have an allergic reaction.