Denton suffered a similar injury 12 months ago in the final game of the previous season which ruled him out of Scotland's summer tour.
And although Denton has now completed the necessary protocols and is deemed fit, Cotter admits he will not be taking any risks.
"He's cleared to start training with us and he'll be followed throughout the prep and pre-season," said Cotter.
"We want to be as careful as we can. He wants to be playing with us. He's back on track, done everything and he's ready to go. We know the potential he has, he's a very good rugby player and we want to put him through the preparation.
"I think it's fair to him and fair to the team because he offers a lot. We're firing ahead with everything. It'll be a robust pre-season."
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