The Wigan goalkeeper picked up the problem during a collision with Emmanuel Adebayor and was in obvious anguish as he received treatment.
He played through the pain barrier in the 3-1 victory over Burnley and looks set to keep his place for Saturday's clash with Portsmouth.
The injury is getting better but Kirkland concedes it has been impossible to take a normal part in training.
He said: "My hand is getting better but it is still a little sore. I had a pin put in to keep things in place.
"Then against Manchester City the ball hit my fingers and bent the pin into the joint. It meant I could not bend my finger.
"At Burnley it was numbed slightly, so I was able to play. I cannot do the same training routine at the moment so I am working on other areas."
Kirkland's opposite number at Fratton Park will be David James and he is fully aware of the veteran shot-stopper's abilities after training with him on England duty.
"To be still playing at 39 is a great achievement," Kirkland told Wigan's official website.
"He looks after himself and is a tremendous athlete. From training alongside him, I know how good David is."