ST KILDA captain Nick Riewoldt has spoken of his difficult 2011 season that was plagued with form inconsistency and off-field issues that included his sister's health battle.

In an extensive interview with the Herald Sun, Riewoldt spoke openly about his younger sister Madeleine's fight against aplastic anaemia, which has seen her treated at the Peter MacCallum Cancer Centre for 12 months.

He also admitted he spent the majority of the season angry about a host of issues - including the fall-out from the Saints' second Grand Final loss in as many years, the release of a naked photograph that appeared on Facebook, and the behaviour of former manager Ricky Nixon - that were headlines prior to the new season.

But, he said his sister's personal fight - which began in the first week of finals last year - superseded anything he encountered off the field this season.

"I didn't carry a picture of her in my sock when I was playing, or anything like that, but I think about her a lot," he told the News Limited tabloid.

"At times you feel really stupid ... being worried about your form and this and that, and here she is in hospital. You feel like an a---hole for being worried about your issues when she has a far bigger fight.

"Football is important because you invest so much into it, but in the grand scheme of things it pales into insignificance."

Madeleine's condition means her body's bone marrow isn't capable of making enough new blood cells, and her doctors initially thought she had leukemia.

Riewoldt said a bone marrow donor had since been found in France - and would be used if needed - after he and brother Alex were found to be incompatible for donation.

"It's hard to see someone in your family go through that, but so many people do," Riewoldt said.

"She's an eight-cylinder car running on one cylinder. It's almost like, she's got this, she's not well, but let's just get it fixed."

Riewoldt also admitted he would have acted differently to the release of the naked photo - taken by teammate Sam Gilbert and leaked out by teenager Kim Duthie - if he had his time again.

"Clearly, I made mistakes at the start of the year with the way I handled things and reacted to things," he said. "I probably wouldn't do the press conference.

"I just automatically felt the need to defend myself. I just really struggled through the whole thing, to understand why it was happening.

"And I struggled to understand the level of interest and I think that's where the anger and frustration with it came from.

"All year I've been silent about it. I felt there was more dignity in saying nothing after the press conference. And to be honest I wasn't ready to talk about it until now.

"A lot of it was in my own mind and that made it a lot worse than what it was. I built it up and up and up to the point I was paranoid."

He said his relationship with Gilbert improved within a month of the release, and they roomed together in New Zealand during the Saints' pre-season training camp in January.

He said his relationship with former manager Nixon - who lost his licence to represent players as a result of his "inappropriate dealings" with Duthie - was "nowhere near as strong as it was".

He also said he felt the statement he made at the club's annual general meeting in February that attacked the media and public for "trying to break us down" was a mistake and "not what people needed to hear".

And, he said while he was "really disappointed" when former coach Ross Lyon visited him in hospital last month to tell him he was leaving for Fremantle, he didn't feel as though he'd abandoned the club.

Riewoldt assessed his own year as "crap" and said he "wasn't up to it" across the season, but believed there were no excuses and was determined not to have another year like this.

"Every year I've handled on-field and off-field and this year I don't think I handled it as well as I have in the past," he said.

"At times, I looked angry and my body language would have suggested that, but I think my body language was the result of my performance and because I put such a high expectation on my performance and I didn't perform to that level, that affected me, absolutely no doubt about that.

"Personally it's probably been the most eventful for a range of reasons.

"Obviously everyone knows what happened with the club this year, but one thing that shone was what we were able to achieve.

"To be 1-8 and to fight back the way we did, I'm really proud of the club and the boys."

Riewoldt has had surgery to promote regeneration in the cartilage of his knee last month, and is keen to put 2011 behind him.

"I've learnt a lot this year, and the ability to say that you make mistakes and you're human is probably the biggest thing."