"We'll need to know whether that's going to need a pin, but he'll miss a few weeks with that."
Sidebottom's injury took the gloss off a superb performance from Collingwood, just four days after Lachlan Keeffe and Josh Thomas were provisionally suspended for testing positive for a performance-enhancing drug.
Collingwood destroyed the Lions in the first three quarters to lead by as many as 53 points, and despite the Lions' late surge, Buckley was full of praise for his men.
"We basically dominated the game for the best part of three quarters," he said.
"We gave the opposition a sniff because we didn't finish a couple of chances at the end of the third quarter and gave ourselves a bit of a scare.
"But I thought the leadership and pluck in that last eight minutes to hold the game and do what we needed to do was pretty good."
Buckley said skipper Scott Pendlebury, defender Alan Toovey and ex-Cat Travis Varcoe were among the experienced heads that kept composed under pressure.
He said despite the players overcoming a tumultuous week off the field to get the four premiership points, the impact of the drugs situation was far from over.
"It takes some time for that shock to settle in," Buckley said.
"I wouldn't think it would be truly absorbed yet by the players.
"Their immediate reaction is to feel for their teammates, to support them. The club's immediate reaction is to provide support for those two players and the players and staff of the footy club and we'll continue to do that.
"It's not going to be done in a week, it's not going to be done in two weeks. It will transpire as the season progresses.
"I've spoken to the players but I have deliberately not asked about specific events because I'm not sure where that takes the investigation."
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