COPENHAGEN, Denmark (AP) — Norway’s King Harald V was admitted to the main hospital in Oslo to undergo surgery for an injured tendon over his right knee, the palace said Friday.

The 83-year-old king’s surgery is scheduled for Saturday and he will be on sick leave until Feb. 14, the royal household said. His son and heir to the throne, Crown Prince Haakon, is taking over his father’s duties.

Harald underwent a heart valve replacement last year to improve his breathing. Doctors ruled out COVID-19.

The king’s aortic valve was replaced with an artificial valve in In 2005. Such valves have an expected lifespan of 10-15 years, the royal household said.

Harald is Norway’s head of state, but his duties are ceremonial, and he holds no political power.

He ascended to the throne following the death of his father, King Olav, on Jan. 17, 1991.

The country’s first native-born king since the 14th century, he won hearts in his egalitarian country by leading the national mourning in 2011 for the 77 victims of mass killer Anders Behring Breivik.