A sprained ankle is one of the Afflictions the player can receive in The Long Dark. It can be gained in a variety of ways: Falling from a high place, moving while overburdened, or sometimes, through getting attacked by Wolves or a Bear.
A sprained ankle will not lower a player's Condition by itself, but it will make the player move much slower until it is treated, and prevent sprinting and climbing.
To treat a sprained ankle, the player must either take two Painkillers or a cup of Rose Hip Tea. The condition will immediately be cured after this. Alternatively, they can rest for four hours, and the condition will be gone upon waking.