The midfielder was taken to hospital after he was stretchered off with a knee injury during the first half of Saturday's 2-2 draw at Huddersfield.
"There appears to be no damage to his bones but clearly he's done some ligament damage," said manager Russell Slade.
"We don't know the extent of that and he'll need a scan before we know."
Orient will also be without on-loan Tottenham striker Harry Kane at the Emirates after he was sent off in the second half.
Source: PA
Source: PA