Not yet investigated
What we have so far
Not a lubricant that sits there — it is squeezed out of the cartilage under load, which is why joints that never move stiffen and joints that move stay wet.
This star is on the map because the show intends to take the question apart properly — the trials, how it is actually tested, whether the thing sold is the thing studied. That work is not done yet, and nothing here should be read as a conclusion. When the investigation is published it will appear on this page.