Torres underwent initial surgery in January but aggravated the problem during the Europa League win against Benfica last month.
“He had his initial surgery a few months ago and made a reasonably good recovery from that,” added Brukner.
“But then in the first few minutes of the Benfica game here at Anfield, he hyper-extended his knee and re-injured it.
“He still managed to score a few goals, so even on one leg he’s not too bad, is he?
“We felt that even with a period of rest it wasn’t going to heal by itself and it needed another telescopic surgery just to trim the area that’s been torn.
“That would enable him to fully recover and play, not just in the World Cup but for many years to come for Liverpool.”
