Abnormal foot pressures alone may not cause 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.