Joel's injury was both extremely cringe-worthy and demoralising. As soon as the enemy attacked and the cut scene began it was known that some form of trouble was right around the corner for the male lead. Joel should have died multiple times on his road to recovery but Ellie was able to keep him breathing for not only two encounters with the cannibals, but for an extended period of time in the freezing cold as well. Had he died, the game would have taken a huge shift in the opposite direction and Ellie would have had to survive by her lonesome. The stakes laying on Joel's injury were for his life and Ellie's too. His attempt at getting Ellie to safety will gushing blood out of his midsection was a valiant effort and gave real insight into his character development and how he grew from only dealing with Ellie to facilitate a weapons deal to actually caring for her as if she were his family. The movie will have a lot to play with here in terms of how the injury will look. Being extremely gory would certainly look gnarly but it could also come off as silly and too much. It would be safe to assume buckets of blood and painful grimaces from Joel will be prominently featured in this part of the plot.