@onwillowbay You have been going through a lot. It is very painful to have a leg fracture and have to bear weight on it; even during the recovery phase after you've been 6 weeks in a cast, it still hurts a lot to try to bear weight. You are dealing with swelling, aching and throbbing, and muscles that are too weak and the tendons and ligaments get stressed and complain. I had a bad fracture of my ankle of the tibia and fibula that was compound, dislocated and was a bad sprain of the tendons and ligaments during the injury. Obviously something was missed if you are waking up from a knee replacement with a fractured tibia or if that fracture could have happened when you started to bear weight on it. I agree with Amanda that a second opinion would be a good idea.

The pain from breaking my ankle was far worse and for a lot longer than the pain I had from cervical spine surgery. Hardware and implants may cause cause pain too or immune responses from foreign materials in your body. That doesn't happen to everyone, but it can happen. I had titanium hardware on my ankle, and 6 months after the fixation surgery that placed them, I was getting pain and chronic hives. I had to stay on antihistamines all the time because when that wore off, the hives came right back with a vengeance. I had to wait at least a year to have the hardware removed and I still have weakness and some pain. When I do too much or walk too much on uneven ground, my ankle fatigues and starts to hurt and I have to get off if it and I am 2 years past the injury.

I think the recovery from fractures is much longer than we think it is supposed to be, and recovery is in baby steps and you can't rush it. Your body is doing a lot to try to heal itself and rebuild bone. If you suspect an immune problem, there is a lab in Chicago that does a blood test for reactions to orthopedic implant materials called Orthopedic Analysis that you can find at https://www.orthopedicanalysis.com/. There is treatment for immune responses and you can find information at this environmental medicine practice in Texas. https://www.ehcd.com/

I know 6 weeks time sounds like a long time to wait to see your doctor again, but that is kind of standard in healing bone because healing is beginning on the cellular level, but it takes longer to start to deposit minerals like calcium to harden the bone. It forms first as cartilage and converts to bone. With my spinal fusion, it took 3 months until there was visual evidence of bone deposition and when there was no movement of the fused area with flexion of my neck on an X-ray where they measure it on the computer screen. This was evidence that the fusion had begun and that would continue over the next couple years to add more bone and strength. As far as imaging goes, MRIs show not only bone, but soft tissues like cartilage, ligaments, nerves, blood vessels, etc. Bone shows up well on X-ray because of the density of the tissue due to mineral deposition. I haven't had a knee replacement, so I don't know that recovery. Your doctor should be answering questions about why this happened, but it is possible that they do not know that answer. You do need information as to what is best and advice on how you can help improve your healing from this point forward.