I've had a handful of successes in these patients. Typically in younger patients who are dancers/gymnasts and don't actually have Baastrups but just hyperextend and irritate things. One patient I will never forget - early on in my career - stylet came out of the needle and fluid started dripping out. I almost S*** myself thinking I wet-tapped her. Turns out it was synovial fluid (she had a slight spondy - posterior ligamentous complex inflammatory syndrome).
I place the needle into the bursa, inject 0.5-1cc of steroid/lido, retract til I'm in the ligament and then inject the rest.
I just bill a TPI + fluoro. Not sure if it gets paid.