"Further examination in the hospital revealed that he also suffered a pulmonary contusion and pneumothorax," said his team Visma-Lease a Bike.
The Danish rider was taken to hospital after the incident on Thursday in the fourth stage of the race in northern Spain and diagnosed with a broken collarbone and several broken ribs.
"He is stable and had a good night. He remains in hospital," added Visma.
The mass crash occurred with around 35 kilometres to go in the run from Etxarri Aranatz to Legutio.
Various other big names were involved in the crash including Remco Evenepoel, who suffered a broken collarbone, and Primoz Roglic, who abandoned the race but did not sustain any fractures.
Last week Visma rider Wout van Aert suffered similar injuries in another bad crash at the Tour of Flanders one-day race.
Roglic, who also fell on Wednesday in stage three but quickly recovered, was leading the overall standings from Evenepoel by seven seconds at the start of racing on Thursday.
With many star names out of the race, Mattias Skjelmose is the new general classification leader, four seconds ahead of Juan Ayuso.
Friday's fifth and penultimate stage is a 175.9km ride north from Vitoria-Gasteiz to Amorebieta-Etxano.
