I have chronic neck problems, and the jerky rides really bother me too. Besides the obvious, I would tell you thatExpedition Everest was much better in the very front and 7DMT is the SMOOTHEST roller coaster-type ride I’ve ever been on.
Off the top of my head here’s what I think:
At MK I would avoid: Space Mountain, Big Thunder Mountain, Tea cups, Barnstormer
At Epcot I would avoid: Test Track, Mission Space
At HS avoid: RRC, HTT, and TSMM. I don’t know yet about SDD and AS2
At AK avoid: EE (unless you want to try the front), Dinosaur, Primeval Whirl
He should be good for most everything else. There is still so much to do!!
I have occasional back issues, but mine are more muscular than osteo. These are my recommendations. Any of the coasters could be an issue; SM is by far the worst - I would defi avoid that one. RRC is also pretty rough. EE has a good deal of vibrations, but no real hard jerks. Dinosaur is one of the roughest in WDW (but I love it too much to skip it.) I don’t think TSMM should be a problem; it jostles s bit, but it’s pretty smooth. I’m surprised that people are saying TT; it’s never impressed as being “jerky” (but I don’t ride all that often as I just don’t really like it all that much). Teacups are notorious for inducing nausea, but they don’t really put much strain on your back. All of the “dark” rides should be fine. I hate to m nation it because it’s one of my favor rides in WDW, but KS drives over some areas of rough terrain, so it does jostle you around a bit.
Toy Story jerks quite badly when it first starts up from the loading area. After that the starts and stops are much smoother. So once I am in the car to ride TS I brace myself until we are moving, and then I am fine for the rest of the ride.