A protective boot adapted to be worn by individuals when lying in a reclining position. The boot has leg and forefoot portions that provide foot and lower leg support for a wearer while suspending the wearer's heel. The boot may include low-friction materials at an exterior surface of its leg and forefoot portions and at a continuous rim separating the exterior surface from an interior surface of the body, in which case the boot also preferably includes a system for adjustably closing an anterior opening in the forefoot portion by drawing lateral regions of the forefoot portion inward and together. The boot may additionally or alternatively include an L-shaped backplate having portions located at the leg and forefoot portions of the body and adapted to inhibit buckling of the boot within the leg and forefoot portions.