"As the injury means he will miss the start of the tour, Ian McGeechan and his fellow selectors have called up James Hook to the squad for the tour to South Africa."
Commenting on the replacement, Lions head coach McGeechan said: "After analysing our requirements for a replacement as we head to South Africa on Sunday, we decided that James was the ideal person to come into the tour squad.
"A very important consideration for us was to strengthen the goal-kicking options in the squad.
"James is an accomplished goal-kicker and has scored over 200 points for his country in his 33 appearances.
"Also, he has played at out-half, centre and full-back for Wales but is also comfortable at outside centre.
"Three of these also play in the Ospreys team with him, that also includes Tommy Bowe. Therefore there is an existing understanding between all of these players.
"James has been pulled out of the Wales tour to Canada and USA by the Welsh Rugby Union.
"He was due to leave with them today for Canada but instead James will now join us in camp in Bagshot.
"We are very grateful to the WRU for releasing James for the British & Irish Lions tour," McGeechan added.