The 69 year old Scottish actor - who is best known worldwide for his role as Hagrid in the Harry Potter franchise - has been left unable to walk due to the severity of his pain.
Awaiting knee surgery
The condition, which causes the joints to become painful and stiff, has forced Coltrane to rely on a wheelchair as he awaits life-changing knee surgery in the US.
The actor was recently seen in a wheelchair when he made an appearance in London on Monday (11 Mar) to help with the launch of the new Universal Orlando attraction, Hagrid's Magical Creatures Motorbike ride.
A source told The Sun, "Robbie has been in constant pain for years now, with his knee constantly deteriorating.
"It's left him unable to walk without any assistance and he's been given a wheelchair while he waits to have a special surgical procedure in America to repair his joint.
"He was wheeled in and out of the Harry Potter event on Monday which cam as a big shock to fans, given they're so used to seeing him standing strong and tall as Hagrid.
"It's hugely frustrating for him, but he's really hoping to be back on his feet after getting the operation."