melted screw?

i had acl surgery 3 years ago. all was fine and dandy til about 6 months after i had my son. then my knee started to give out on me again. i saw the dr, he said that the cadaver ligament that had been placed in my knee had most likely been a tad too big, and had been stretched too much, and that i needed a new one. i decided to wait til my son was done breastfeeding to do the surgery. the dr said this would be fine, and to be careful.

6 months later, i notice sever knee pain over the series of a week or so. i was sitting down one night, and i felt a large bump on the bone in my knee. it alarmed me, so i went to see my dr. (he was not the dr who performed my surgery)

the dr did an x ray, and told me that the dr who had done my acl surgery had used plastic screws to hold everything in place.
these screws were supposedly supposed to pretty much disslove into a tissue like substance.

the bump on my bone that i felt was one of the screws coming back out of the hole it went into, melted. my current dr is telling me that i now have to have surgery to remove the screw, and replace it. 6 months later, my acl repair can be done.

am i crazy to think its crazy that mu dr said that plastic is melting out of my knee? help!