I have to say that I was a bit suspicious when there was never a case of one having broken. If there is no known failure mode then either there haven’t been enough of them installed for long enough to find out what the failure mode is, or someone is covering it up (Bill Gates == #1 suspect always). Knowing that an animal the size of a 4 door sedan can do it under specific circumstances actually makes me feel better about having one implanted, since I can’t stand any animal larger than me that can’t do algebra[1] and thus will not be around them.
[1] If a non-human animal can do math I will give it a pass because that is pretty exceptional.