Thompson blow for Gers
By Graeme Bailey
Last Updated: 01/01/70 1:00am
The Scotland star picked up the initial injury against Everton in pre-season and then he aggravated it against Dunfermline earlier this month.
"It's a blow because he has been playing well," said Gers boss Alex McLeish.
"He has cemented his place in the squad.
"I'm really sorry that he is missing when his form was really good.
"Going under the knife means he's going to be out for a couple of months, maybe more."
With injuries robbing him of both Thompson and Ronald de Boer, McLeish has added Chris Burke and Andy Dowie to his squad.