Sam Smith was absent from the matchday squad for the victory over Kim Hellberg’s side.
The striker sustained a knee injury in the latter stages of Wrexham’s 1-0 loss to Sheffield United at Bramall Lane on Friday night.
Prior to the win against Middlesbrough, Parkinson confirmed the 28-year-old was set for a spell on the sidelines.
In the aftermath of the contest, the manager revealed Smith is set to undergo surgery next week and will be sidelined for the remainder of the campaign.
“Unfortunately with Sam, he’s done his cruciate,” Parkinson added.
“He’s going to be out for nine months and faces the operation next Wednesday.”
Wrexham have been dealt numerous injury issues this season, with Josh Windass, Nathan Broadhead, Liberato Cacace and Callum O’Hare among those currently sidelined.
But Parkinson said he would not accept players feeling sorry for themselves, something he felt may have been the case at Sheffield United last time out.
“We’ve had injuries in other years, we’ve had setbacks, we’ve always dug deep,” Parkinson said.
“I felt at Sheffield United we looked like a team that had almost taken one blow too many, but I’m not accepting that.”