The news is bound to be a sickening blow for the forward who was making his first start for the R's since the fixture at Watford in early August having battling back from persistant ankle injuries.
"Thorpey" went down under a heavy challenge from West Ham centre-half Tomas Repka after half an hour of Saturday's clash at Upton Park.
The Czech defender was cautioned for the foul which brought hefty criticsm from Rangers boss Ian Holloway.
Olllie last week dealt with the news that Martin Rowlands will be out of action for a similar period of time having broken a bone in his foot.
Both players have already eyed up a Christmas return to the Rangers first team, hoping all goes well for both.
Elsewhere, Arthur Gnohere returned to match action today in the reserves fixture at home to Aldershot.
Arthur played 45 minutes as he looks to regain fitness and challenge for a first-team place.