prosthetic had been acting wiggly

[KLPNO]

Hi everyone
I'd like to ask a question about the meaning of the phrase 'to act wiggly' in the following passage.

But his prosthetic had been acting wiggly, and the docs didn't want to risk him taking a suborbital journey, so he didn't go. That decision saved his life.

Does the phrase 'his prosthetic had been acting wiggly' mean 'his prosthetic wasn't reliable'? And is 'prosthetic' the same as prosthesis?

[Conchita]

Yes, this is how I understand it too, KPLNO.

[KLPNO]

Thank you very much, Conchita.