Adam Clarke on Genesis 32:25

The hollow of Jacob's thigh was out of joint - What this implies is difficult to find out; it is not likely that it was complete luxation of the thigh bone. It may mean no more than he received a stroke on the groin, not a touch; for the Hebrew word נגע naga often signifies to smite with violence, which stroke, even if comparatively slight, would effectually disable him for a time, and cause him to halt for many hours, if not for several days. I might add that in this place - the groin, a blow might be of fatal consequence; but as the angel gave it only as a proof of his power, and to show that he could not prevail because he would not, hence the blow was only disabling, without being dangerous; and he was probably cured by the time the sun arose.