gogogogdm,
It is possible for the holes left behind by the screw removal to cause stress risers, thus making it easier to fracture through them. But, if that did occur you would have had the acute pain from a fracture directly at the screw location. You would have known it if you broke the tibia again. Plus, the treatment for it would be an IM nail, which was already in place. After 8 months, any new fractures should have also healed by now. And again, the pain would have pain around the screw sites, not the midshaft.
The use of titamium was selected for orthopedic implants, not because it is some space age metal, it has actually been around for a long time, but because its bending modulus is almost identical to that of bone.
When the screws were removed, the nail went from a stress shielding to a stress sharing construct. As such, the fracture site is now having more stress go through it than before.
You also have to remember that when you break a bone, not just the bone is injured. All of the soft tissues around the bone are also hurt. The periosteum is ripped apart, the muscles are torn from their attachmets, the fascia, ligaments, tendons, blood vessel, and nerves are all stretched and twisted in the injury. All this soft tissue injury has to heal and it heals with scar tissue. Scar does not stretch as well as regular tissue. So, around the fracture site, there is a lot of healed soft tissues, which could be causing some of the discomfort also.
As to removing the IM nail for occasional pain, is controversal. If hardware is causing problems, if it is proud, broken, rubbing, etc then its removal usually takes care of the problem. But, to remove hardware that is buried in the bone, well, the outcomes are not as reliable.
To remove the nail, the original incision at the knee has to be reopened. Removal is easier than putting it in of course. But, the knee has to be violated again.
But, you should be able to walk immediately after the procedure, taking it easy for a week or so, till the surgical wound heals.
Will it take your pain away, maybe, maybe not. A big thing to make sure of, before removing the rod, is that the tibia fracture is absoluately, completely healed. Once that nail is no longer there, the tibia is going to have to be taking all of the stresses. And pain at a fracture site, not coming from the soft tissues, is worrisome for at least a partial nonunion. Something is causing the pain and it is often too easy to blame the big piece of metal seen on x-ray.
This is one of those decision you will have to make, depending upon how much the pain bothers you and if you want to go through another major operation.
You will find patients that thought removal of the hardware was the best thing they did and others that say they should have just left it in, that they are worse off afterwards.
Being 60 is not as important as your overall general health. If you have diabetes, significant heart problems, etc then surgery would, of course, be more dangerous. But, if you are healthy, don't smoke, limit alcohol intake, then your age is not a really big factor.
You should discuss all of yours questions and concerns with your surgeon. Then, once you have all the information, make an informed decision. Good luck.