Sorry, it's not one with the middle ball, but I have totally happy with my Sanwa trackballs (I have both the wired and wireless models).
They are credible replacements for my discontinued and beloved Logitech TrackMan MarbleBall devices.
Note that your thumb is actually the strongest digit on your hand. If your thumb can't take it, use a mouse.
Sanwa is not a recognized brand name in the USA but they have been around for 50+ years.