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.