Originally Posted by
summit
Just to clarify:
Grade I is a partial rupture (sprain) of the AC while a
Grade II is generally a full rupture of the AC with usually a partial for the CCs.
Generally the definition of the grades varies because of differences in human anatomy which some relying on the CC distance increase relative to the other side either in raw mm distances or percentages (assuming it is not otherwise injured) and/or the displacement of the base of the distal clavicle relative to the "top" of the acromion process for II v III v V. The CC distance vs the anatomical clavicle-AC line is a useful consideration for people with naturally "compact" CC distances. These variations in "how to grade" vs human anatomical are how I was diagnosed with everything from a I+ to a V-.
