Diabetes Care, Vol 22, Issue 12 1966-1970, Copyright © 1999 by American Diabetes Association
Plantar pressures are elevated in the neuroischemic and the neuropathic diabetic foot
DL Pitei, M Lord, A Foster, S Wilson, PJ Watkins and ME Edmonds
King's Diabetes Centre, King's College Hospital, London, U.K.
OBJECTIVE: Clinical observation has noted that diabetic neuropathic ulcers
occur frequently on the plantar surface, whereas neuroischemic ulcers seem
to occur often on the foot margins. The reason for this difference in the
site of ulceration is unknown, but it may be related to differences in
pressure loading. The aim of the study was to compare vertical in-shoe foot
pressures measured during walking (using the F-SCAN system) in four groups
of patients whose degree of neuropathy was measured by vibration perception
threshold (VPT). RESEARCH DESIGN AND METHODS: Subjects included 14
neuroischemic diabetic patients (VPT 29.3 +/- 13.5 V) with history of
ulceration on the margins of the foot, 18 patients with neuropathy alone
(VPT 38.7 +/- 12.7 V) and previous history of ulceration on the plantar
surface, 10 diabetic control patients (VPT 9.9 +/- 2.7 V), and 15
nondiabetic control subjects (VPT 7.0 +/- 0.5 V). RESULTS: When compared
with the other three groups, neuroischemic patients had higher foot
pressures when measured as mean peak pressures and highest peak pressures
under four areas of the foot: medial and lateral forefoot, hallux, and
heel. Furthermore, when measuring the maximum pressures developed at any
point under the plantar surface, the neuroischemic patients also had the
most elevated pressures (757.6 +/- 135.9 kPa), significantly higher than
those found in the neuropathic group (482.8 +/- 68.6 kPa, P = 0.04) and in
both diabetic control patients (310.2 +/- 34.7 kPa, P = 0.008) and
nondiabetic controls subjects (365.1 +/- 49.8 kPa, P = 0.007). CONCLUSIONS:
Despite having increased plantar pressures and a comparable degree of
neuropatny, the neuroischemic patients did not have a history of ulceration
on the plantar surface. These observations may have relevance to different
mechanisms of ulcer formation in the neuroischemic and neuropathic foot.