A "kicker" is a term for a diagonal brace to a stud wall (pony wall more than likely), where the stud wall is framed above a concrete wall. The concrete wall retains earth and does not have lateral support via a floor diaphragm at the top. This kicker serves to transfer the lateral pressure from the soil to the floor diaphragm above. The kicker does not have to frame to the top of the concrete, but may intersect the studwall at a position between the top of the concrete wall and floor diaphragm.
The "Knuckle joint" I refer to is the joint(at the sill plate) between the top of the concrete wall and the pony wall. This joint has no fixity to resist the soil load, so it is treated as a pinned joint. This condition is not critical for yielding walls, but can be critical for non-yielding, or basement walls that are not full height. That is why I refer to the condition as a "Knuckle Joint".
Sorry if I mislead anyone here.
Mike McCann
McCann Engineering