Roche limit
The orbit of Adrastea lies inside Jupiter's synchronous orbit radius (as does Metis's), and as a result, tidal forces are slowly causing its orbit to decay so that it will one day impact Jupiter. If its density is similar to Amalthea's then its orbit would actually lie within the fluid Roche limit. However, since it is not breaking up, it must still lie outside its rigid Roche limit.