Former Swans defender and premiership player Alex Johnson is nearing a return to the field following a sixth knee reconstruction.

The 27-year-old signed with Carlton's VFL affiliate Northern Blues over summer, and will be looking to have an injury-free season as he eyes off an AFL return.

Johnson suffered yet another devastating ACL injury during Sydney's Round 20 match-up against Melbourne last year, which marked just his second game since the 2012 Grand Final win.

The defender was delisted by the Swans at the conclusion of the season, after backing him through a rehab process that sidelined him for 142 consecutive matches.

Northern Blues general manager Ben Brennan has praised Johnson's impact off the field at the Blues, mentoring the young core who have suffered similar injuries in the past.

"He's an absolute ripper," Brennan told the Herald Sun. 

"Around the group he's setting standards, particularly around leadership. I couldn't speak highly enough of him.

"He's running around, he's - I don't have the (medical) word - but he's zigzagging at training.

"It's the knee he hasn't done and never had an issue with before. We'd love to see him pretty early in the season."

Johnson was offered a coaching role at the Swans last year, but chose to continue his journey at the Northern Blues.

"Alex has been an incredible servant of our club and has shown unbelievable resilience and he's a much-admired player among his teammates, coaches, staff and wider AFL community," Swans coach John Longmire said.