Geometric, shape and area measurement considerations for diabetic neuropathic plantar ulcers

Though neuropathic plantar ulcers are known to be "round-like," systematic quantitative data on their shape and geometric features are not readily available. A sample of 305 ulcers were retrospectively assessed to provide distribution data on quantitative geometric and shape parameters. After tracing the ulcer during the patient's initial visit, the following parameters were determined: surface area (A), maximum length (L), maximum perpendicular width (W), perimeter (p), shape factor (SF), and an ulcer regularity index (URI). SF assesses ulcer "circularity" and URI measures ulcer perimeter "smoothness" in comparison to a fictitious circle with the same contained area. SF and URI values of 1.0 correspond to 100 percent circularity and regularity. These data and the associated distributions, which are derived from a reasonably large random sample, provide a useful quantitative description of plantar ulcer geometry and shape.