De Plus crashed during the opening stage in Barcelona on Saturday and scans revealed he had suffered a fractured hip.
"He underwent a range of imaging on an injury sustained to his right hip, which showed a non-displaced fracture," Ineos Grenadiers said in a statement.
"A treatment plan for Laurens is currently being finalised and we look forward to him making a full and speedy recovery."
The absence of Belgian De Plus is a blow to Ineos Grenadiers general classification contender Geraint Thomas (37) as he would have been a domestique in the many mountain stages to come.
Ineos Grenadiers placed eighth in the team time trial, 20 seconds off the pace of stage winners DSM-Firmenich, although other fancied teams also struggled in the conditions with Jumbo Visma - including co-favourites Jonas Vingegaard (26) and Primoz Roglic (33) - only 11th quickest at 32 seconds.