Prince Philip was sporting a bandage on his hand when he took part in two official engagements on Wednesday, including the first garden party of the season at Buckingham Palace with his wife, Queen Elizabeth.
In a statement, the palace tells PEOPLE, "The Duke of Edinburgh had a minor procedure carried out on his right hand [Tuesday]. The procedure was performed at Buckingham Palace, and the Duke will be wearing a bandage for protection."
In recent years, the 92-year-old has undergone a series of operations, including the insertion of a stent in a coronary artery at Christmas 2011 and a procedure on his stomach that required a three-month convalescence.
But he has been increasingly active in recent weeks – and will join the Queen and other members of the royal family in France early next month to mark the 70th anniversary of the D-Day landings.
Only last week he was seen participating in a favorite pastime, carriage riding, at Windsor. He used to take part in the sport competitively but gave that up a few years ago.
As for the healing hand, "The only reason people know about this is because he has been out and about and so active," a palace source tells PEOPLE. "It's extraordinary that he is still out in the park, carriage riding and doing so much."