The 25-year-old versatile back, who joined Edinburgh in 2004, sustained the knee damage in a pre-season friendly against Sale back in August.
But after going under the knife, Cairns faces an extended spell on the sidelines that will come as a blow to Michael Bradley's men who have made an inconsistent start to their RaboDirect PRO12 season.
And with Cairns, who was only cut from Scotland's World Cup squad before the final 30 were announced, out of action their chances of turning things round have certainly not been helped.
Furthermore the English-born back's plans to add to his seven caps for his country have also been hampered as the surgery will only grant him minimal time to recover and prove his fitness ahead of next year's RBS 6 Nations.
An Edinburgh Rugby spokesperson said: "Ben Cairns, will be unavailable for selection for at least 12 weeks following arthroscopic surgery on the knee he injured in the club's pre-season friendly against Sale Sharks on Friday 19 August.
"The time taken has allowed a full assessment of Ben's knee with the outcome of the investigative 'key-hole' surgery a positive one, in that it revealed minimal damage to Ben's anterior cruciate ligament (ACL), which would have required a more invasive operation and a longer period out of action.
"During this time, Ben will be reassessed regularly at the Spire Murrayfield Hospital and receive continuous rehabilitative support from the expert medical team at Edinburgh Rugby."
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