Ive had three cartlidge trims on right knee and crutiate ligament rupture.also one trim on left knee .I keep going but sometimes think until when.If my knee is hurting tend to do some cycling,as for long term who knows.
There doesnt seem to be many runners that dont have some injury ,but like you say we just run through it.
Im forty and not ready to stop yet,keeps my sanity as well as the weight off.
Not much help but thats my experience ,hope its some help.....