A special feature of the Revo 2-D hip joints is the 7+7 degree positioning of the movement axis.
The first joint angle, seen from the front, is slanted 7 degrees from the vertical in order to permit pelvic rotation. This rotation represents movement of the trunk in relation to the lower extremity, which allows the legs to remain aligned in the chosen walking direction.
The second 7-degree angle, viewed from above, is slanted inwardly and anteriorly. It allows the joint axis to be anteriorly offset and prevents pinching during sitting.