Jeffery, if the plastic spacer is broken, parts of it should show on X-Ray. They have a line in them that is radio-opaque.
The spacer in my PKR broke suddenly. Half of it shot out the front of my knee and the other half went towards the back.
At revision surgery, my surgeon was able to retrieve the part from the front of the knee, but the part at the back had embedded and encapsulated itself in the soft tissues at the back of the knee - the "tiger country" where surgeons try not to go, unless it's absolutely necessary. So, there it sits, not causing me any problems. It shows up on every X-Ray that is taken of my knee.
I think it's important to determine if your spacer is broken. If it is, the implants in your femur and tibia will be rubbing on each other and you could get small parts of them wearing off and getting in your knee compartment.
At my revision surgery, it was discovered that small metal filings from the implants had turned the soft tissues black and the fluid in my knee was bright green.
It might be possible for you to just have the spacer replaced.