ethel rider , 87 , dropped from her bed at half acre care home in radcliffe .
was left cowering on the floor for 40 minutes and sustained pelvic fracture .
carers lauren gillies , 25 , and susan logan , 59 , covered up the incident .
they have now been jailed for six months each for concocting story .
ambulance finally called only when another carer saw her howling in pain .