Maybe "channel" isn't the correct term - the top of the back and arms had "puffs" (?). Like tying twine around a sausage. Sort of. Looked crappy under the slip, anyway.

And we're still friends. Don't know what she did with the Sure-Fit... haven't asked, not sure I want to...

PS: I am exceptionally fortunate that I did not inherit my mom's arthritis - her knees and back are toast.