Buckman was due to meet a specialist about his injured shoulder late yesterday but whatever the prognosis, he will not be back on the field for the foreseeable future.
Buckman injured his left shoulder when scoring a try against Racing 92 in Hong Kong on Saturday night.
The injury could be season-ending, depending on the diagnosis, or he may spend about two months in rehabilitation, strengthening the shoulder before resuming training.
Head coach Jamie Joseph said Buckman was a tough player and would not have left the field if it was not serious.
The best outcome for the Highlanders would be a couple of months off the paddock for Buckman.
If he needs surgery, his season will be over.
Joseph said there were options for the Highlanders at second five-eighth with candidates such as Rob Thompson, Tei Walden, Jason Emery and Malakai Fekitoa.
Walden, who was now part of the Highlanders leadership group, would start in the match today against the Crusaders.
Fekitoa had played second five-eighth for the All Blacks, while Emery had also played in the position for the Highlanders.
Thompson has yet to take the field for the Highlanders.
