The invention relates to an exoskeleton sub-assembly (30) comprising: —a leg part (32) to be attached to a leg of a user, and —a foot part (33) to be attached to a shoe of the user； the leg part (32) comprises a tibial segment (321) extending below the knee, along the tibia of the user, when the leg part (32) is attached to the leg, and the tibial segment (321) comprises a first component (325), a second component (326) connected to the foot part (33), and a first joint (327) connecting the second component (326) to the first component (325), the first joint (327) permitting a rotation of the second component (326) with respect to the first component (325) caused by an internal or external rotation of the user's foot with respect to the leg.
