The pressures and loads under the feet during walking have been compared in three groups of 41 patients each, using a microprocessor-controlled optical system. Group A consisted of patients with diabetic neuropathy, group B of non-neuropathic diabetic patients, and group C of nondiabetic controls. Thirteen patients in group A had a history of neuropathic foot ulceration. Other investigations in the diabetic patients included motor conduction velocity (MCV) in the median and peroneal nerves, vibration perception threshold (VPT) in the great toes, the valsalva response (VR), skin resistance (SR), and the ankle pressure index (API). Fifty-one percent of neuropathic feet had abnormally high pressures underneath the metatarsal heads compared with 17% of the diabetic controls and 7% of nondiabetic subjects. All those feet with previous ulceration had abnormally high pressures at the ulcer sites. Of the other investigations, the VPT correlated most significantly with the presence of foot ulceration. In addition, a low median and peroneal nerve MCV, an abnormal VR, a high API, and the absence of sweating all correlated with the presence of foot ulceration. We therefore conclude that simple bedside investigations, such as measurement of the VPT alone, may be useful in identifying those patients at risk of foot ulceration. Foot pressure studies may then be used in such patients as a predictive and management aid by determining specific areas under the foot that are prone to ulceration.

Dynamic foot pressure has been studied in 44 diabetic subjects of mean age 52 years with no clinical evidence of neuropathy and in an age and sex matched non-diabetic control group. Vibration perception threshold (VPT), sensory (SCV), and motor conduction velocities (MCV) were also measured in the diabetic subjects. Sixteen diabetic subjects (Group A) had abnormally high pressures under the metatarsal heads (greater than 10 kg/cm2), whereas the remaining 28 diabetic subjects had normal results (Group B). The ratio of toe to metatarsal head loading (normal 0.112) was significantly reduced in Group A (0.077) compared to Group B (0.127: p less than 0.05). VPT and sural nerve SCV were also significantly abnormal in Group A subjects compared with Group B (p less than 0.005 and p less than 0.02, respectively), though there were no differences in MCV. A significant inverse correlation was obtained between toe loading and VPT. It is concluded that abnormalities of foot pressure occur in early sensory neuropathy and may precede clinical abnormalities. Assessment of the toe-loading ratio may provide a sensitive measure of motor dysfunction in early diabetic neuropathy.

Static and dynamic measurements of foot pressure have been carried out on three groups of subjects: diabetic patients with neuropathy (with and without a history of ulceration), diabetic patients with no neuropathy, and normal subjects as confrols. In many cases both techniques of measurement detected areas of abnormally high pressure under the foot, but in some cases a particularly high-pressure spot was detected on only one of the tests and sometimes both methods were needed to reveal all the areas of the foot which might be considered to be at risk. The dynamic measurements tended to show multiple areas of high pressure better than the static measurements. Our results indicate the importance of making both types of measurement when seeking to devise suitable means of protecting the foot from ulceration.

Both rheumatoid arthritis and diabetes have been associated with the development of abnormally high pressures under the feet, and ulceration has been considered to be a problem in both conditions. In order to examine further the relationship between high foot pressure, neurological abnormalities, and ulceration, we have studied two groups of patients: (a) 38 diabetic patients and (b) 37 patients with rheumatoid arthritis who had similar clinical abnormalities of the feet. Thirty-two percent of diabetic patients had a history of plantar ulceration compared with none of the rheumatoid group (p less than 0.01). However, the diabetic group had considerably more severe neuropathy (peroneal nerve motor conduction velocity 35.4 +/- 4.8 m s-1 vs 44.4 +/- 5.2 m s-1 (mean +/- SD), p less than 0.001; vibration perception threshold 33.5 +/- 13.4 vs 16.9 +/- 10.9, p less than 0.001), with a similar frequency of elevated plantar pressures (51% vs 61%, NS). These data emphasize the importance of the loss of sensory awareness in the pathogenesis of diabetic foot ulceration, and suggest that high pressure alone is not a direct cause of ulceration.

An apparatus is described which gives a rapid and detailed picture of the distribution of pressure under the foot, this being displayed either as a continuous grey scale or a color contour map on a television monitor. Automatic analysis systems are outlined which enable the quantitation of the distribution of pressures and loads under the foot during standing and walking, utilizing computer techniques. The use of the static system is illustrated by the results of analytic procedures carried out on normal feet and in the assessment of surgical correction of a series of equino-varus feet in children suffering from spina bifida. The clinical application of the dynamic system is illustrated by the measurement of pressure/time curves encountered under the heel, the five metatarsal heads, and the great toe of a control group of feet and the feet of patients who had undergone metatarsophalangeal fusions, Keller arthroplasties, and Swanson arthroplasties.