Edinburgh and Scotland lock forward Grant Gilchrist has undergone groin surgery.
The 25-year-old picked up the injury during the World Cup and is now a doubt for the Six Nations.
Gilchrist was named Scotland captain ahead of last year's November Tests but soon suffered an arm injury which ruled him out for the rest of the season.
And his World Cup ended during Scotland's second game, when he was injured against the United States.
"Further specialist opinion revealed some damage to soft tissue structures which had not previously been clinically evident," said a statement from Edinburgh.
"Following best advice from the specialist, it was decided that surgery would be the most appropriate course and this has already taken place."
Gilchrist, capped 12 times, has spent his entire professional career with Edinburgh.