Kyrie does not have knee problems like Chris Paul.
The only major knee surgery Kyrie had was when he got injured in the 2015 Finals.
Last season's knee surgery was a follow up to that 2015 surgery.
Other than that, Kyrie's only other major injury was back in college when missed the majority of the college season due to a toe injury.
So it's not true that Kyrie is not durable.
Ainge would've traded Kyrie, at the trade deadline, if the Celts had no plans of giving him a max contract after this season.
What Ainge and the Celts are envisioning is a tandem of Kyrie and AD for many years to come.
Not counting this year Kyrie has played and most likely started 441 out of 558 games (six full length seasons 6 x 82 plus 1 lock out season of 66 games) which is 0.7903 or roughly 79% and is equivalent to 64.8 games in an 82 game season.
Again not counting this season, Chris Paul: 892/1050, 0.8495 or 69.66 games in an 82 games season.
So Paul actually has a better games played percentage or whatever you want to call it.
Now most people would classify Chris Paul as prone to injury.