Interesting... Do you have a link?
No link on hand. But I know the difference between an HA block and/or a JAW IMPLANT made from an HA block vs a type of 'goop' (HA paste or HA granules) that is spread over the surface of the bone. The OP was clearly referring to an 'elbow shape' and an HA BLOCK and not the stuff that is spread onto the bone surface that is associated with a lot of inflammation.
HA can come in a BLOCK that can be carved. HA can come in the form of a ready made implant. HA can come in the form of PARTICULATE MATTER (granules) that can be mixed up as a paste like substance to spread over the bone. HA particles can also be found in filler material (like Radiesse) used as soft tissue filler where the aim of it is for the particles to kick up inflammation to surround the particles which, in turn, kicks up the soft tissue augmentation ('favorable fibrosis).
Gunson uses HA granules which he mixes with some substance in the blood and uses it to overlay onto an area. That stuff kicks up a lot of inflammation. Also, HA BLOCKS (to be carved) are used in LARGE CCW down grafts or any significant downgraft.