Due to the length of expected time for full rehabilitation on his heel, the decision has now been taken, following consultation between the medical teams at the WRU and Cardiff Blues, for Cuthbert to also have an operation on a long-standing knee issue.
Cuthbert, 25, has this week flown to see a specialist in Sweden and has had minor surgery to resolve a tendon issue in his right knee.
The wing will now commence a period of rehabilitation that is expected to take 12 weeks.
"Alex was already out of action with a heel injury and due to the length of time he was set to miss the decision has been taken for him to also have surgery on his knee," said Head Coach Danny Wilson.
"Clearly Alex will be disappointed to miss the end of this season with Cardiff Blues and the chance to go on the summer tour with Wales to New Zealand.
"However, this decision has been taken for his long-term health and so we wish him well as he commences his rehabilitation."
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