The 19-year old midfielder has undergone successful microfracture surgery on his right knee at Salt Lake Regional Medical Center.
Allen will miss the rest of the 2014 campaign but Dr Andrew Cooper, who performed the operation, expects him to make a complete recovery.
"I'm pleased to say that Jordan's surgery went very well this morning," Cooper said.
"While he has a lengthy rehab process ahead of him, we fully expect Jordan to make a complete physical recovery in time to return to the field next preseason."
Allen joined RSL as a Homegrown Player in December and has appeared in two MLS matches in 2014.
For breaking stories and all the great banter like us on Facebook: facebook.com/tribalfootball