O'Brien could return for start of Six Nations
Ireland flanker Sean O’Brien could be fit for the start of the Six Nations after undergoing surgery, while Robbie Henshaw will be out for up to six weeks with a hamstring injury.
O’Brien suffered a broken arm during the victory over Argentina, Leinster confirming the British and Irish Lions star had gone under the knife.
The 31 year-old will be out for between eight and 12 weeks, so may be back in time for the start of Ireland's Six Nations title defence at the Aviva Stadium on 3 February (AEDT).
Leinster team-mate Henshaw was ruled out of the historic victory over New Zealand and faces at least a month on the sidelines.
Dan Leavy also missed the win over the All Blacks with a strained neck and will not face the United States in Dublin on Saturday.
