Sometimes, for a whole host of reasons, cicadas are not able to successfully molt from their nymphal to their adult stage and they get stuck inside their exuvia. When they get stuck their body will still harden inside the exuvia and then they become deformed into whatever shape they are in when they get stuck. You can usually find these individuals stuck to the sides of trees still stuck inside their exuvia or at the base of the tree, either stuck inside or sitting there unable to fly because their wings are too deformed.
It is unlikely any of these cicadas will ever mate and very likely they will be nabbed quickly by predators. It makes me so sad that they are able to survive those 17 years underground only to have something go wrong during the best part.
Sometimes you can peel away the sides of the exuvia and give them a chance to at least walk around in the world a little bit, even if they can't fly. This poor little one was far too stuck and for too long - her legs were completely deformed and she couldn't walk. She won't survive long but I will still love her just the same and thought you might love her too.