Thompson will undergo an operation on Friday to repair ligament damage for an injury which initially baffled medical experts.
The problem was eventually discovered by a specialist and the Scotland international has been booked in for surgery later this week.
Scottish champions Rangers fear the forward will be out of action for six months but Thompson is determined to be back on the field ahead of schedule.
"My injury is very unusual in modern-day footballers," admitted Thompson. "It is ligament damage on the lateral part of the right knee but it is not cruciate ligament damage or anything like that.
"I was told I would be out of action for three to six months and I am facing an operation but I hope to be playing within four months.
"I am still hoping to play again this season but that will all come down to how quickly I recover.
"It is a massive blow as I will be missing for all the big games coming up but at least I have peace of mind I have a diagnosis, and there will be no recurrence once the knee has healed."
