She was injured in her fight with Cinder

Winter Schnee was recovering from the latest, and hardest battle she had fought. In her attempt to defend the Winter Maiden, Fria she had to go up against the current Fall Maiden and minion of Salem, the deranged Cinder Fall.

While she barely managed to hold her off with the help of the android supersoldier who inherited Fria's Maiden powers, Penny Polendina, Winter was heavily injured in the fight.

After the current attack on Atlas was resolved General Ironwood had her admitted to the military's medical ward. It also turned out one injury affected her the most.

"Winter, do you need your diaper changed?" Penny asked bluntly.

Yeah... that...