Article continues below advertisementRobert Plant is feared to be nearing his final days after undergoing a brutal knee replacement operation.The 77-year-old rocker admitted years of performing on stage has taken a savage toll on his body, leaving him with no choice but to go under the knife to get one of his joints replaced because he can no longer play sport.Explaining why he has been using a walking stick, he said ahead of the procedure: "Ooh! I'm having a knee replacement next week."Article continues below advertisementSource: MEGAThe star has to undergo knee replacement surgery.