The 33-year-old New Zealand international missed the end of last season to undergo the serious procedure.
“Unfortunately we lost Ryan towards the end of last season, he had quite a major operation on his knee,” Kean said to Sky Sports.
“He’s taking part in some of the sessions but talking to our medical team, they’re confident he’ll be fit for the start of the season which is tremendous.
“We’ve got a senior group that’s very important to us and I’m confident he’ll be fit for the start of the season.”
Blackburn survived relegation last season but boss Kean maintains that the wealth of experience Nelsen has could fill the void left by Phil Jones, who has left for Manchester United.
The Scot insists that whilst Manchester City are splashing out millions of pounds on rejuvenating their squad, Blackburn will work on the youth players and continue cherish the seniors.
“Different teams have got different models,” he added.
“Manchester City want to spend, they want to achieve and go very quickly. We’re going to do it slightly differently.
“We’ve got the senior players like Michel Salgado, Paul Robinson, Ryan Nelsen – we’ve got a senior group and then we’re going to continue to improve the young players.
“It’s a case of each to their own.”
Read more from the original source:
‘It will be tremendous to have him back’ – Blackburn Rovers boss Steve Kean thriled with Ryan Nelsen’s recovery