The reports claim that the man had been playing the game everyday pretty much non-stop for 6-8 weeks, so much so that he developed chronic pain in his left thumb. According to the doctors, the man had ruptured one of his tendons thus requiring surgery to fix it. The tendon that was injured was the one that allows you to extend your index finger.
Interestingly enough it seems that the man, despite his Candy Crush marathon, was not addicted to the game. Apparently he was just playing the game extensively as a means to pass the time in between jobs after he had left the military.
According to JAMA, “The potential for video games to reduce pain perception raises clinical and social considerations about excessive use, abuse, and addiction. Future research should consider whether pain reduction is a reason some individuals play video games excessively, manifest addiction, or sustain injuries associated with video gaming.”