Torn MCL five weeks after knee replacement

I have a unique situation as I had liposarcoma ( cancer) in my surgical leg twenty years ago so my knee replacement was risky as I Have damage to my bones because of radiation and also have osteoporosis in the bones. I am missing two hamstrings and have a weak quad muscle. Five weeks after surgery, I found out I had torn my MCL and now am wearing a hinged brace to see if the MCl might heal properly. If the MCL doesn’t heal properly, I wonder what might come next? I also have a bowed out surgical leg again as I did before the surgery. Immediately after the surgery the leg was straight.

Is another surgery the only answer or is that too risky considering my leg? The surgeon has brought up the idea of amputation which I might consider. But what about the problems that come with amputation?

Any experiences like this? What to do?

Thanks