When I was going down the barn's (http://dayz.gamepedia.com/Barns) left staircase from the entrance perspective I made a small fall less than an inch or just a few frames when I was turning away from the staircase towards the center of the barn and heard my character grunting as to see my leg was crippled. May be a problem with fall damage appearing in heights with very small proportions from the air to the ground. Too early fall damage. When I tried to reproduce the problem I did not fall this time but walked straight forwards down the stairway, a few seconds later I was unconscious with no sign of hostility around.