Elpenor steps on the crack of Zeus enlightenment of Athena and breaks his back not his mother's matriarches Circe's back.

Elpenor who was the youngest member of Ulysses crew was the one who drank and broke his back on Circe's island. He represented a newer yet more uncontrolled Greek that was not indicative of the Greeks represented by Ulysses.
If one observes in each tale the Greeks who represented the virtue embodied by Ulysses do not coincide with the folly of the Greeks he tries to lead to virtue and peaceful alliance. The Greeks represented by Ulysses are peaceful , bearing new sailing tech and those who create alliances. In Circe's story There are the virtuous Greeks embodied in the idea of Ulysses, the average less virtuous ones who turn to pigs and those yet rip, who become drunk with the wisdom and power of the matriarchal society represented by Circe who break their backs to catch up and in doing so, and yes catching up, die out as a separate Greek from Ulysses and are in fact buried as a dead paradigm on Circe's island. If this is true and Ulysses tail encompasses the enlightenment the Greeks go through as they grow into a people representative of the virtue encompassed by Ulysses he will end up journeying alone , representing all Greeks as the embodied paradigm of his being.
As this is the case one can safely say this interpretation holds strength based on the tales of the Odyssey thus far exposed and interpreted.

Ulysses returns to Circe's island and hurries Elpenor and marks the end of the Greek who broke his back to become one with the wisdom that intoxicated and enticed them to be as virtuous as the paradigm of Ulysses entailed.

More next week
Peace