Osbourne was forced off in the abandoned Premiership clash with St Johnstone on Saturday and had a scan yesterday afternoon to discover the extent of the damage.
The former Aberdeen star has been one of Thistle's most consistent performers following his summer switch to Firhill. The Jags will find out in the coming days how long he is likely to be out of action, but Bannigan says his absence would be a huge blow to Alan Archibald's side.
He said: "Ozzy has been a great signing. He is great to have around the dressing room, he is an experienced player and really helps the younger players.
"He would be a big loss if he was to miss a few games. We will just have to wait and see what the problem is.
"He has been great in every game, you can count on him to perform and you know he won't let you down.
"He played right-back in the Aberdeen cup game and did a job for us again.
"He teaches you things all the time. I feel stronger playing alongside him, he does a lot of the physical side of the game for you and lets me get on the ball. He has been excellent for us so far this season and hopefully he will be back playing as soon as possible."
After seeing their Saints clash called off at half-time due to a waterlogged Firhill pitch, Thistle head to Rugby Park this weekend aiming to finally end their wait to record another top flight win.
Archibald's side saw two points slip through their grasp at home to Kilmarnock earlier in the campaign and with just two points between them in the Premiership, Bannigan knows there would be no better time to add to their tally after a long winless run.
He said: "I am looking forward to the Killie match. It should be a good game between two teams who are close to each other in the league table.
"We can open up a wee gap over them with a win and we have a game in hand over them now too. We are certainly looking to go there and get a win.I thought they played well at times when they came to Firhill.
"If you give them chances, you will get punished because they have a lot of quality in the forward areas.
"We are going through a sticky patch just now but we will come out of it.
"We should have taken three points at Hibs but we just need to stay positive and I am sure that the results will come for us."
Thistle fans have until December 29 to buy tickets for the trips to Celtic and Hearts.
Briefs for the Parkhead clash must be bought from the Firhill offices in advance of the game, while the Jambos will have a cash gate on the day of the match.