Scotsman Ridgers, 26, has been released by Orlando City B, the Major League Soccer side's second string.
Stuckmann joined Thistle in September after leaving Doncaster Rovers and the 35-year-old played five times for the Scottish Premiership club.
But first-choice Tomas Cerny has returned from injury.
Stuckmann, who previously played for Preussen Munster, Eintracht Braunschweig, Alemannia Aachen and Preston North End, played in two wins and three defeats.
Ridgers began his career with Ross County but had to wait until Hearts sent him on loan to East Fife before making a first-team appearance.
He also had a spell at Airdrie before being given his Hearts debut.
However, he only made four appearances for the Edinburgh club before moving to St Mirren in 2014.
Ridgers was released by the Paisley club last January after a short loan spell with Kilmarnock and joined Orlando in the United Soccer League.
He made 28 appearances as his side finished eighth in the table in the 2016 season.
Partick Thistle have signed former Hearts and St Mirren goalkeeper Mark Ridgers after Thorsten Stuckmann came to the end of his contract at Firhill.