Alex Johnson’s promising AFL career has taken another hit, with the luckless Sydney defender needing a fourth knee reconstruction.

Johnson was 20 years old when he won an AFL premiership with the Swans in 2012, having played all 25 games that year.

He tore his anterior cruciate ligament (ACL) the following pre-season and underwent a traditional knee reconstruction plus two LARS operations.

But a persistent infection has hampered his rehabilitation and, after going under the knife again this week to remove his latest LARS graft, needs more surgery.

No timeframe has been set for the reconstruction or recovery.

“It is obviously very frustrating but I have no choice but to attack the situation with a positive attitude,” Johnson said in a statement on Friday.

“It has been a difficult couple of years but I love football and while I understand the challenge ahead, I am determined to get back out playing.”

Fellow Swan Nick Malceski praised his teammate’s optimism and backed him to add to his tally of 45 AFL games.

“Devastated for my premiership brother having yet another knee reco. But i know AJ will bounce back with his positive attitude and resilience,” he wrote on Twitter.