>>12480796>metal grafted to bone?MD here, have some experience with orthopedic complications.
In many cases there's no problem with these implants, they are banged into the the center of the femur and get stuck there, some models are attached with cement. All fine.
Complications that can happen is that the bone reacts to the artificial materials and start to get resorbed. Bone is a living tissue and if it breaks down faster than it is formed then, well, the prostethic implants is no longer attached and you have a problem. For weight bearing metals in the body there's also metal fatigue. Unlike bone the metal implant is not being reshaped so after 20 years of walking on it the metal simply breaks in two, this is why hip replacements aren't a problem to do in say 70 year olds who are likely to be dead by the time the implant fails, but much worse to be done in 40 year olds who will need an implant revision of a metallic device that was cemented into their femur before the end of their life, now getting that shit out is a major problem.
Other options for thing like skull replacement that don't need to bear loads can be bioglass and whatnot, problem there is again bone resorpotion and fibrous reaction of the meninges and whatnot, I'm not experienced with that so I'm a bit thin on details.
For implants/electrodes that need to communicate with nerves the main problem is the fibrosis. Body packs the implant into connective tissue which means the signal to and from nerves drop off, making the implant less effective and eventually useless. And the connective tissue may bind to the surrounding living tissue making it nontrivial to remove the implant to put a new one in its place.
tl:dr: Body changes tissue in contact with implant, making it lose good contact and signal conduction, replacing implant means carving out something surrounded by a rigid scar, not easy anywhere but a hell to do near a brain or nerves.
