The 27-year-old was struck down with the problem last month after making an impressive start to his time at the KC Stadium with four goals in 10 Premier League appearances.
However, he limped out of Hull's 1-1 draw with Everton at the beginning of last month and has not featured since, despite originally only being expected to be out for three weeks.
Scans showed rest should help heal the problem with his tendon, but - a month later - Bruce revealed the Senegal international remains a long way from full fitness and may not feature again in 2014-15.
"Diame is still in a knee brace and has another couple of weeks in the brace," said Bruce. "He's been in the knee brace for the last few weeks now and he's still a long way off from making a full recovery.
"He and [Robert] Snodgrass have picked up awful injuries which have been by fluke.
"There is the possibility that Diame could be out for the rest of the season, and it all depends on how he is when he comes out of the brace.
"We will just have to wait and see and hope that nature takes its cause."
Diame arrived at the club in September after a two-year spell with West Ham that saw him make 79 appearances for the east London club.
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