Hi,,,, yes,  I know a great deal about joints swellings but then I have RA.
I do not know what kind of arthritis your have or what you take for it.   I
do not know what kind of doctor you use that loves big words that end up
being a lack of information.   Good luck with it though.
Harv

hey f

i wasn't diagnosed because of it, but as a still's disease RA, i do have
associated inflammation of clavicle, sternum, and ribs

for those that don't know where we're talking about sternoclavicular joint
is that meeting point of the clavicle - the [collar]bone that goes from the
front of the shoulder area over on a downward diagonal to the
sternum/breastbone. this bones primary purpose it to provide additional
shoulder support

the joint that 'f' is referring to is that which joins the sternum, see:

http://yahooligans.yahoo.com/reference/gray/illustrations/figure?id=325

this one shows the entire bone structure: http://tinyurl.com/an7df

note that there is a disc between them, cartilage, and the whole thing is
covered by a large ligament.

if you rule out traumatic injury - this would be not be uncommon given your
age http://www.wheelessonline.com/ortho/sternoclavicular_joint_injury],

then immune response inflammation will/can cause significant discomfort,
and if unchecked erosion damage, including disruption of the synovial
membranes