The Official Online RBS 6 Nations Store is open. The store has everything you need to get behind your team during the RBS 6 Nations, plus the store is now fully stocked with a much wider range of rugby merchandise.
The 29-year-old escaped a fracture but still faces around three weeks on the sidelines before he can contemplate a return.
Horgan will definitely miss Leinster’s Magners League clash with Ulster on Boxing Day.
Leinster coach Michael Cheika said: "It isn’t a fracture, which is good, but sometimes cartilage damage - if that is the final diagnosis - that can just be the same distance in time.
"So we’ll be looking to re-assess him in a few weeks."