The 36-year-old was on a month-long spell at Firhill, which was due to expire on March 21.
Partick manager Ian McCall told the club's official website: "He will see a specialist to try and determine just how serious a leg break it is.
"A leg break is obviously a bad injury at the best of times and our hope is that it is nothing more than a break and that there isn't - and we don't think there is - any cruciate ligament damage into the bargain.
"The best-case scenario is that he will be fit for pre-season training at the end of June/start of July."
Falkirk are already without centre-back Pedro Pele for the rest of the campaign and the news cast a dark shadow over the club's training ground today.
The Bairns face a three-point deficit at the foot of the Clydesdale Bank Premier League but manager Steven Pressley has been encouraged by his players' response in his first month in charge.
Falkirk have lost three times against top-six opposition in four SPL games but created a number of chances during Sunday's 2-0 defeat by Celtic.
Pressley, whose side host St Johnstone in the SPL on Saturday, said: "Over the last three or four weeks our performances have been to an extremely high standard.
"As a manager, I don't think I could have asked for any more than what the players have given me.
"At the weekend I thought we created the greater opportunities, more clear-cut opportunities, unfortunately we didn't manage to take them.
"But we're very encouraged by it and the players are in a really positive mood.
"They can see that they are playing well and they can see that by taking a couple more opportunities, we will certainly start winning games."
Source: Team Talk