nerve fatigue after surgical implants

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A friend who had surgery to mend a congenital heart defect over five years ago claims it still bugs her to feel "jutting edges of steel that was supposedly used to tie her sternum back together", presumably when she moves or positions herself wrong. Is this possible, and if so how? I always thought a nerve or brain region being stimulated by something constant like the presence of surgical implants would fatigue quickly and block out the stimulus. Even if the stuff does shift around inside her and vary the sensation somewhat, wouldn't that feeling merge into the background of all other sensations caused by movement and go unnoticed after five years of exposure?

My friend says she has no idea how what she describes is possible...so I turn to you...

[SandyHook]

I broke my leg in 1987 and ended up having a pin put in. Every once in a while I'm aware that there's something in there. It doesn't hurt or limit my use of the leg. It's like having something in your pocket, you just know it's there. Like you I thought this was something that would go away. But it happens much less now then, say, 10 years ago.