Theuns crashed during a high speed decent and suffered a compressed fracture of the T12 vertebra.
"I was feeling good in the TT, having a good tempo, and my legs felt good. I was planning to ease back more at the end because I had made a good tempo until then," Theuns said.
"I came into a downhill corner at around kilometer 23 and the wind grabbed my wheel and I had to correct a little and went off the road. I thought I had it, but then hit a tree trunk on the ground and went over my bike and landed quite hard. I directly felt that my back was not okay."
The team said that further tests revealed the compression fracture was unstable and Theuns will have to undergo surgery.
The fractured bone requires stabilization through surgery due to the high risk for neurological complications.
"I feel very disappointed because I was feeling good and was going okay and now suddenly everything comes to a stop," Theuns said.
"The pain is not bad, but I am forced to not move my body and its very uncomfortable. I am nervous about the operation.