"I think he'll be back around Christmas but it's a long road ahead," manager Andy Hessenthaler told BBC Radio Kent.
"He is progressing but he's had a nasty one there, I've seen the scan. The kid's desperate to come back and he's just got to be patient."
Even if King does manage to resurrect his career after Christmas, Hesenthaler thinks it will take even longer to get back to his best.
"He's been out for so long," said the Gills boss.
"He hasn't half got to do a lot of work fitness-wise but he's working hard and we are hoping to get him back."
Source: BBC Sport
Source: BBC Sport