Can people affected by leprosy at risk of developing plantar ulcers be identified? A field study from central Ethiopia

In the ALERT leprosy control programme, 75 people affected by leprosy, in t hree different geographical areas, were investigated. Each person was docum ented as having anaesthesia to the 10 g monofilament. The study sought to d etermine why some people developed ulcers whilst others did not. According to the records, 43 had an ulcer during the last 5 years but 32 had never ha d an ulcer. In order to examine protective sensation on the sole of the foo t, various sensory modalities were tested and the functional anatomy of the foot was examined. The results showed, as may be expected, that it is not possible to define a specific threshold for protective sensation that could be applied to all cases. Some people with only slightly diminished sensati on developed ulcers, while many others with almost complete anaesthesia rem ained ulcer-free. In these rural communities, being a fanner reduced the ri sk of developing an ulcer, but no other demographic features were significa nt. Graded monofilaments were found to be the most appropriate test, with l oss of sensation at any of five points tested being a 'positive' result. Th e 10 g filament was the most sensitive, but only 43% of feet identified by this test actually developed an ulcer. As people with partial loss of sensa tion were excluded from this study, this figure may be lower under programm e conditions. The 50 g and 100 g filaments decrease the number of feet iden tified as at risk, but increase the percentage which actually develop an ul cer, to 46% and 49%, respectively. An appropriate test for selecting those for special programmes which may have a limited capacity, for example the p rovision of subsidized footwear or involvement in self-care groups, would b e a 100 g filament, which would detect 86% of those feet likely to develop an ulcer, while reducing the number of those selected who are not at great risk. Vibrometry was found to be no better than graded filaments and an exa mination of functional anatomy did not help in identifying those at risk.