Prosthetic/orthosis spring layer(s) with composite rivet(s)

A composite prosthetic foot comprising:

• a first spring layer, the first spring layer comprising a cantilevered upper portion and a lower portion;
• and
• a second spring layer coupled to the first spring layer,
• wherein the first spring layer is coupled to the second spring layer with a twisted carbon fiber rivet, the rivet comprising a first layer of unidirectional fiber or multidirectional fiber or both, the first layer having a twist present in it, the twist of the first layer imparted by the first layer having been twisted about a longitudinal reference line of the rivet,
• wherein the second spring layer is a sole plate.

A prosthetic foot comprising:

• a J-shaped keel, the keel comprising a cantilevered upper portion and a split pronged lower portion;
• a first sole plate coupled to a first prong of the split pronged lower portion;
• a second sole plate coupled to a second prong of the splint pronged lower portion,
• wherein the first sole plate is spaced apart from the second sole plate along an entire side adjacent to the second sole plate.