GEELONG defender Lachie Henderson is in doubt for the start of the home and away season and might not return from injury until as late as round four, according to Cats coach Chris Scott.

Henderson had surgery on his right knee at the end of last season. Upon his return to training, he couldn't shake persistent pain in the joint, so underwent another operation shortly before Christmas.

Scott told AFL.com.au Henderson's injury was not serious, but his rehabilitation had proven slower than expected.

"I think it's fair to say he's in doubt for round one. We all get nervous when we start approaching round one. It can feel like the finish line to some extent when the reality is obviously that it's a long season and round one is no more important than round eight or round 18," Scott said.

"We'd love to have Lachie in our team, but if we don't we think we've got pretty good cover for those taller defenders.

"At the moment, my best estimate is (he'll return) somewhere between the week before round one and round four, or somewhere around there.

"Importantly, it's not something we think is going to limit him through the season. It's just a matter of getting it completely right and that just takes a bit of time at this stage.

"It's not a serious issue and it's one that the surgeons and the doctors say should resolve itself, but for Lachie it's just really frustrating at the moment because it's a bit slower than expected."

The Cats' other major injury concern ahead of round one is Scott Selwood, who had surgery on his right ankle in late January to remove a bone fragment.

Scott said Selwood's operation had been successful and should help the midfielder get on top of the ankle problems that had plagued him since 2014, his second last season at West Coast.

But the Cats coach acknowledged Selwood also faced a delayed start to the premiership season.

"The feedback is really positive in that there was a specific issue that they were able to fix," Scott said of Selwood's operation.

"Sometimes those procedures can be a bit ambiguous and you can come out sort of not knowing really whether it's going to definitively help the problem.

"This involved a bone fragment that they were able to take out. It was a bit slower because it wasn't floating and they had to dig it out of the joint a little bit more.

"Again, he'll be slow but we're really confident that he'll be actually better in two months' time than he was late last season."