"They smoothed over some of the cartilage and cleaned out the knee. The Surgeon, Rhys Williams, was very positive and I hope to be back earlier than expected probably in late September or early October."
Should Rush return to action by October he could form part of the squad that will travel to Italy to face Calvisano in round 1 of the Heineken Cup.
The following week will see Rush's side face Gloucester in the big-money match up at the Millennium Stadium in round 2.
A return to rugby for Rush would be welcome news for Blues boss Dai Young. The on-field presence of the former All Black bow row helped the Cardiff team to their first quarter-final since regionalisation in 2003.
"We won't rush him back," said Young. "Player welfare is hugely important. He's had the operation and the specialist was really pleased with it.
"It's now just a matter of his rehabilitation and when we feel he's ready. "I think he's going to be out for at least six weeks. The prognosis is he's back sometime in September."