Richmond forward Chris Knights has had a breakthrough in his lengthy return from a serious knee injury, with another round of surgery three weeks ago revealing a piece of floating bone that been stonewalling his recovery.

Knights, who has not played at senior level since round seven last season, has experienced multiple setbacks since tearing the patella tendon in his right knee more than 13 months ago.  

The 27-year-old underwent a knee cleanout last month that could have ended his season, but it instead uncovered a crucial piece of the puzzle that could have him back in full training in the coming weeks. 

"There were a couple of options on the table and [the doctor] said, 'If we go down this path it could be the end of your season'," Knights told richmondfc.com.au.

"At the end of the day I couldn't just be waiting for my knee to get better and really training under duress.

"I said, 'Whatever I do from here on it has to be an aggressive decision', and it turned out after the surgery I was able to walk out of there and it felt really comfortable.

"I'm really glad I went down that path."

Knights was on track to play in round one this season after appearing to put the injury behind him over summer, but he broke down in a practice match against Essendon in late March.

He has spent the past three weeks rehabilitating his right knee following surgery and is now completing light football drills and almost sprinting.

The former Adelaide half-forward, who joined Richmond as a free agent at the end of 2012, said the past year had presented the toughest mental challenge of his 101-game career.

"There's been times where I've thought, 'Enough is enough. What am I doing? I feel like I'm letting the team down and my teammates down'," he said. 

"At the end of the day you talk to the ones that care about you most – whether it's the coaches, your family, your partner – and they say, 'You're not letting anyone down, you didn't mean for this to happen', and it puts you back on track. 

"I had a good chat with Ivan (Maric) because he was in a similar position at the start of the year."

Knights has taken on mentoring roles with young players, particularly Matt Arnot, and will often run extra swimming and cycling sessions for teammates, given he is now an expert in those areas.

He has conditioned himself not to set goals from an injury point of view because "sometimes your body doesn't allow you to achieve them", but he hasn't written off 2014.

"I'd like to play AFL towards the end of this year … good AFL football for the team and build a bit of momentum into the pre-season," he said.

"There's no danger of doing a similar injury again, it's more whether it deteriorates.

"That's why I'm spending a lot of time in the gym making sure the tendon is getting stronger.

"I really want to get back out there and do what I enjoy doing most."