The former All Blacks number eight Mose Tuiali'i will have to wear a neck brace for six weeks and won't be able to train fully for three months.
Tuiali'i suffered spinal chord bruising during a lineout in Cantebury's final pool match of the Air New Zealand Cup against Southland in Invercargill just over a week ago.
The injury won't affect Tuiali'i's overseas contract and he will still head to the Yamaha club in Japan has planned next year.
Meanwhile Canterbury and Crusaders hooker Ti'i Paulo has been ruled out for the rest of the Air New Zealand Cup season and next year's Super 14 after injuring his knee late in Friday night's quarter-final win over Tasman.
Paulo, who came on as a replacement for Corey Flynn ruptured ligaments in his left knee and is likely to have surgery next week.