Oh it's worse than that: those hollow semicircular legs buckle and the top arms crack at the hinge and fall off. Ours is somewhat shorter than it used to be, with fewer arms!
I wonder what you have. Rohan "Stronghold Winter" are not lightly insulated and have to be changed for ordinary trousers pretty soon on entering a heated building!
We must have been lucky with ours then, as it must be 6 or so years old, and my parents is something like 15 years old, and has travelled all the way to Spain from the UK, over to Mauritius, then back to Spain!
They did need to buy a new cover, but I think they simply lost the one one.
I saw they have a new design one I think, that has much shorter legs, so perhaps that is why.
The troosers I have, are in all likelihood 'old man' trousers, but they seem to me to be fit for purpose:
Donald's Trooooosers