Objective: The aim of this study was to compare four measurement methods. Digital planimetry was compared with mechanical planimetry, placing the film over graph paper and counting the squares (grid tracing), and multiplying the two maximal perpendicular diameters of the ulcer (diameter product).
Method: Twenty patients with 50 chronic leg ulcers of various aetiology and sizes (20 ulcers were < or = 3 cm2, 15 ulcers were > 3 cm2 and < or = 10 cm2, and 15 ulcers were > 10 cm2) were enrolled consecutively into this study. Ulcer area was calculated from film transparency tracings using a digital planimeter, a mechanical planimeter, grid tracing and diameter product.
Results: The mean difference of digital planimetry versus mechanical planimetry, grid tracing and diameter product was 0.51 cm2, 0.72 cm2 and -5.38 cm2, respectively. For all methods difference tended to increase with ulcer size.
Conclusion: Digital and mechanical planimetry, together with grid tracing, appear to be appropriate means of obtaining accurate surface area measurements. Digital planimetry is a quick and practical method and could therefore be recommended in the clinical setting.