Wickham was injured just a few minutes into his full debut against Cheltenham in the Carabao Cup, having previously made one substitute appearance in the Championship.
He was caught from behind by a challenge when his leg was fully stretched, causing damage to the higher part of the hamstring in his right leg.
The 28-year-old former Crystal Palace, Sunderland and Ipswich centre-forward saw a specialist earlier in the week who confirmed that an operation was required.
He's now had surgery, Wickham posting a message on social media platform Instagram to say it had gone well and the road to recovery had started.
Wickham is on a four-month contract at North End, having trained with them as a trialist for a nearly a month in a bid to earn a deal.
He was released by Crystal Palace in the summer and PNE signed him outside the transfer window as a free agent.
On the injury front, Andrew Hughes' toe injury will be assessed to see whether he has a chance of making the game at Queens Park Rangers on Saturday.
Hughes damaged his toe at Birmingham last weekend and needed a painkilling injection at half-time to get him through the second half.
The defender has since had the toe stitched and he's been on antibiotics.
He missed the midweek draw with Stoke City as a result.
PNE head coach Frankie McAvoy said: "We are hoping we can get Hughesy back in.
"It is a nasty toe injury to be honest, we are hopeful but need to wait and see."
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