Who is this saint?

I took this picture while on holiday in France a couple of months ago.




It's a statue in the church of St Peter in Caen, so possibly it is St Peter and those are keys that he's holding. But what I want to know is, Why does he have his arm in a sling? And is it actually St Peter or someone else?

I've Googled all the obvious combinations of Saint, Sling, Broken arm. And read all the web sites for the church in English and French.

And no, I did look for a sign on the statue while I was there and couldn't see one at the time. There must be a story in that sling.