The _acute bed-sore_ is a rapidly progressing form of ulceration, often
amounting to gangrene, of portions of skin exposed to pressure when
their trophic nerve-supply has been interfered with.
[Illustration: FIG. 15.--Perforating Ulcers of Sole of Foot.
(From Photograph lent by Sir Montagu Cotterill.)]
The _perforating ulcer of the foot_ is a peculiar type of sore which
occurs in association with the different forms of peripheral neuritis,
and with various lesions of the brain and spinal cord, such as general
paralysis, locomotor ataxia, or syringo-myelia (Fig. 15). It also occurs
in patients suffering from glycosuria, and is usually associated with
arterio-sclerosis--local or general. Perforating ulcer is met with most
frequently under the head of the metatarsal bone of the great toe. A
callosity forms and suppuration occurs under it, the pus escaping
through a small hole in the centre. The process slowly and gradually
spreads deeper and deeper, till eventually the bone or joint is reached,
and becomes implicated in the destructive process--hence the term
"perforating ulcer." The flexor tendons are sometimes destroyed, the toe
being dorsiflexed by the unopposed extensors. The depth of the track
being so disproportionate to its superficial area, the condition closely
simulates a tuberculous sinus, for which it is liable to be mistaken.
The raw surface is absolutely insensitive, so that the probe can be
freely employed without the patient even being aware of it or suffering
the least discomfort--a significant fact in diagnosis. The cavity is
filled with effete and decomposing epidermis, which has a most offensive
odour. The chronic and intractable character of the ulcer is due to
interference with the trophic nerve-supply of the parts, and to the fact
that the epithelium of the skin grows in and lines the track leading
down to the deepest part of the ulcer and so prevents closure. While
they are commonest on the sole of the foot and other parts subjected to
pressure, perforating ulcers are met with on the sides and dorsum of the
foot and toes, on the hands, and on other parts where no pressure has
been exerted.
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