Astana team leader Johan Bruyneel says on his Twitter feed that it was a clean fracture without complications. He adds that the seven-time Tour de France champion should make a fast recovery.
Armstrong crashed Monday during a pileup in the first stage of the Vuelta of Castilla and Leon race. He was taken to the hospital by ambulance.
The 37-year-old Texan is making a comeback to cycling and is riding with the Astana team as he prepares for another possible shot at a Tour de France title. He had not raced in Spain for five years.