Valls will undergo surgery to fix the break.
Hansen finished a record 18 straight Grand Tours when he ended the Tour de France in Paris this year in 113th place despite suffering from a bad case of saddle sores. The Australian had initially not been selected to the Lotto Soudal team for the Vuelta.
Hansen broke the record for consecutive Grand Tour finishes after completing the 2015 Vuelta a España. He has also won two Grand Tour stages, one in the Giro d'Italia in 2013 and one in the 2014 Vuelta.
Valls joins Jürgen Roelandts and Frederik Frison on the sidelines for the remainder of the season. Roelandts had hip surgery after dropping out of RideLondon, and Frison has been suffering from glandular fever. Louis Vervaeke is also out of competition recovering from fatigue.