INJURY-cursed Sydney defender Alex Johnson has signed a one-year contract to remain at the club until the end of 2017.

Johnson is recovering from his fifth knee reconstruction and hasn't played senior football since the 2012 premiership win against Hawthorn.

"We have always been committed to giving AJ every possible chance to return to senior football," Swans football boss Tom Harley told sydneyswans.com.au. 

"This, coupled with the fact that Alex is such a quality young man, made for a very straightforward decision. 

"I speak on behalf of everyone involved with the Sydney Swans when I say that we can't wait to see Alex extend his games tally with the club." 

He first ruptured his anterior cruciate ligament in a 2013 pre-season game. In September, the 24-year-old ran on solid ground for the first time in 906 days, and told AFL.com.au how thrilled he was to be back running.

"I grew up loving athletics and doing cross-country running, along with playing footy, so to have something so simple taken away has been really frustrating," Johnson said at the time.

"For some people it is just running, but for me it's a huge step and gives me a lot of confidence going forward."

Johnson joins forward Dean Towers in inking new deals in recent days, with Towers committing until the end of 2018.