The New Zealand international, who had surgery in December, is available for the Europa League quarter-final second leg against Porto after starting in the 1-1 first-leg draw.
Wood admits his knee will never fully recover but remains determined to contribute.
"It's a knee injury, it's going to take years of managing throughout my whole career and when I'm playing with kids, playing golf or doing whatever I do after football," said the 34-year-old.
"It's going be there. I'd say it's always got to be in your back of mind that I have to keep myself in top shape ready to go.
"A knee injury is always horrible, you never know what could happen in the future or how you are going to come back from it.
"So mentally, that's one of the tough things to deal with. But I had confidence I was always going to come back. I got very close to returning pre-surgery and it just didn't happen. That's just unfortunate."