How????

I've got this funny "clicky" joint on the middle finger of my right hand - come about following all the manual work on the shed.
I suspect it is arthritis-like.
The governor was kind enough to get this gel stuff, but how does a great big moecule like glucosamine get through skin ( which is water tight) a bit of flesh, a capsule of cartilage and into the joint?
Hey ho - as Aladdin said "just rub it and see".
BTW the plastic molars are not bad, shame there were no trick or treaters last night, I could have scared 'em witless......