The Omega Pharma-QuickStep rider came off his bike on a slippery descent, with teammate Tom Boonen also coming to grief. Boonen was able to continue however, Terpstra was forced to abandon.
"It was in a corner it was raining and slippery," Terpstra said in a team press release. "They crashed in front of us. I tried to brake but I went straight. I jumped on the bike again but after five minutes I had to stop. There was too much pain. I'm really sad. "
The 28-year-old Dutch national champion was taken to hospital in Jelenia Gora where he was given stitches in his left knee, while x-rays were taken of his injured shoulder.
Initial imaging did not reveal any fractures however he will undergo further examination today in Belgium for a second opinion.
"... the muscles are damaged," Terpstra told De Telegraaf.
"Hopefully that is all and can I just train. Yes, at this moment I am quite afraid I might miss the Olympics."
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The Dwars door Vlaanderen-Waregem winner was the first rider selected on the Dutch team in late April.
