Set to return to the senior side after recovering from a back injury, Bruce suffered a fractured fibula after colliding with a teammate in a marking contest at training.
The injury is likely to keep him sidelined for the remainder of the season.
Josh Bruce is expected to be sidelined for the remainder of the season.
Carlisle will miss the clash with Port Adelaide due to a complication in the treatment of a rib injury, which had him in doubt for this Saturday’s clash.
During treatment of the injury prior to training on Thursday he, unfortunately, sustained a minor puncture to his lung.
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General Manager of Football Simon Lethlean said Carlisle would hopefully just miss the clash with Port Adelaide.
“There is a small risk in treating rib injuries that this type of complication can occur,” Lethlean said.
“We’d love to have them both out there this weekend but the reality is they won’t be, and we will need guys to step up and fill the void.
“We have seen a host of young players take their opportunity over the course of the season, and we need this to continue this week.”