Mystery solved.

It's somewhat embarrassing.

The knackered rib was caused by.......

A wide screen tv. "Dray" said yon Bear, cleaning the tv stand "Have you moved the tv?"

Do I look like Arnold whatsisname? Heck I do. It's big, flat and weighs a ton. Mr. Potato man more like.

But there, in the dust (ahem!) were signs the swivel stand had moved at least 4 inches. The TV is at the side of a door. Suspicious, She had me stand at the side, and sure enough, the top corner of the television matched exactly where the rib is.

I wobble. That's not a complaint. Fact of our life. Sometimes, walking down a corridor - I have a 15 foot hallway - it's just easier to bounce off the walls on the way down. It looks like I bounced a bit too soon, and crunched.

We haven't worked out yet how the heck I didn't feel it at the time, or how no-one noticed.

Bear is now Sherlock Bear :)