Collapsed knee replacement

[mifta]

I went to the hospital today with my mum and we were told her knee replacement that she had 4 years ago (and has been in constant pain with since!) has collapsed and she needs to have much more extensive replacement to fix it. We were also told that if an infection is found in her knee they will remove the old replacement and some of the bone, and leave it for 6 to 12 weeks, without a knee, to clear infection and then put in a new knee in. Has anyone had this done? If so, what does it entail? Will she have to remain in hospital or will it be splinted in some way and she can then come home? I know we should have asked the doctor but we were all a bit in shock.
Many thanks in advance.