_Heat_ and _prolonged exposure to the Rontgen rays_ or _to radium
emanations_ act in a similar way.
The _pressure_ of improperly padded splints or other appliances may so
far interfere with the circulation of the part pressed upon, that the
skin sloughs, leaving an open sore. This is most liable to occur in
patients who suffer from some nerve lesion--such as anterior
poliomyelitis, or injury of the spinal cord or nerve-trunks.
Splint-pressure sores are usually situated over bony prominences, such
as the malleoli, the condyles of the femur or humerus, the head of the
fibula, the dorsum of the foot, or the base of the fifth metatarsal
bone. On removing the splint, the skin of the part pressed upon is found
to be of a red or pink colour, with a pale grey patch in the centre,
which eventually sloughs and leaves an ulcer. Certain forms of
_bed-sore_ are also due to prolonged pressure.
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