Portsmouth missing three players for visit of Rotherham United
The defender was absent as Danny Cowley's side lost 1-0 at Cheltenham Town on Saturday and is not expected to feature against the Millers.
Cowley is hopeful the injury is not long-term but admits it is hard to put a timescale on his absence.
"Denver has picked up a neural issue in his back. We don’t anticipate it being long-term, but it is frustrating because obviously we would like to have played him," said the former Huddersfield Town boss.
"The back injuries are a challenge really in being able to put a time frame on it.
"Sometimes, the soft tissue injuries, you get a scan and they are pretty clear. You can kind of put a time scale to it, but this is a neural issue so you have to just see how it settles down.
"He’s got anti-inflammatories, we are to mobilise the nerve without stretching the nerve because the stretching of the nerve can create irritation."
Portsmouth duo Reeco Hackett (knee) and Kieron Freeman (ankle) are both sidelined for the season and will not play a part tonight.
Cowley has identified areas his side can exploit against Rotherham tonight but admits it will be a tough test for Portsmouth against one of the division's promotion-chasing sides.
"They are a team that have been relentlessly consistent this season. They have lived at the top of what is a very, very tough division. They’ve just won the Papa John’s Trophy," he added.
"They’ve got physical power, they’ve got athleticism, one of the fittest teams in the division. They create a sustained pressure in the way they like to play, they like to create waves after waves of attack.
"You have to be big enough and good enough to stand up to that and then ultimately, find your ways of exploiting them. We know how they defend, they have a man-to-man style and you have to be good enough to play out of their pressure and then exploit the space they leave."