The 75-year-old admitted that he has to go under the knife to fix a problem with his ankle which has left him struggling to walk.
Rod will have ankle fusion surgery, which will fuse two or more bones in the ankle into one piece. This helps stop pain, inflammation and swelling, which is caused when the smooth cartilage on the surface of the bones wears away.
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Addressing his health battle, Rod told The Mirror: "First of all it was my knee as I played football all my life. I am suffering for it now.
"My knee got fixed with a replacement and then the ankle did not know what was going on. It was crooked. So I have had to have an ankle fusion.
"So when this is all done I should have a nice straight leg and I should be able to run." He added: "My leg has been caused by playing on awful pitches in Los Angeles. They are bone dry."
Rod Stewart celebrated his 75th birthday in hospital after knee surgery
"He’s just done two private shows in Florida and he said, ‘My knee is better now than it has ever been’," the Loose Women star told The Mirror.
Penny and Rod married in 2007
"He said he was running sideways and it has all been sorted. He is like a masterclass of knee replacement – and there is no stopping him."
Rod is sadly no stranger to health issues. Last September, he revealed he had been privately battling prostate cancer. When speaking about her husband's illness the following month on Loose Women, Penny broke down in tears as she explained why they kept the diagnosis a secret from the world for nearly three years.
"It was our choice to come out [with the news], as it were. Rod was performing at a prostate cancer event with the Faces. After a few songs, he said, 'Hi everyone, thank you so much for coming and I have to just take this moment, I owe it to everyone, I'm a survivor.'"
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