It happened to me on the 4th of April, 2016!
I was on the third step from the top when the Werner 356 I was on collapsed -- on hard, dry, level grade with spreaders extended, locked, and, even "challenged" as I'm a retired nuclear power guy and safety is always paramount. Didn't know the dubious history of this product until after my fall.
Wound up with a broken arm that appears to be about an inch closer to the wrist than your break, with the characteristic "S" curve, along with, bruised ribs and ego.
Almost 40 years working safely with ladders and not one problem until last month. Fortunately, my fracture reduced and the hard cast came off yesterday -- no need for surgery but I won't be playing the guitar for some time.
I'd be interested about what an independent testing lab would have to say about this:
https://onedrive.live.com/redir?resid=BD16F9E0A9B8940C!1280&authkey=!AHjvEc24E8vKgL4&ithint=folder%2cJPG
I wish you a speedy and complete recovery!