Cutaneous ulcers of various etiologies are common and can be problematic and costly to treat. One of the most basic determinations of wound improvement is a reduction in size from visit to visit. The reduction in wound area over time has been shown to predict wound healing in both venous leg ulcers1
and diabetic foot ulcers.2,3
There are many techniques used to measure the area or volume of wounds. The most simple and standard technique calculates the area by multiplying the longest length by the widest width (l × w
) as measured by a ruler or tape measure. This technique is limited by subjective interpretation and interobserver variability.4,5
Another deficiency with this method is that wounds of various shapes and areas fit into the same linear l × w
The measurement of l × w
is only mathematically accurate for a square or rectangle.
illustrates the difference in l × w
area estimation and true area (TA) for a square, a circle, and a triangle. The l × w
calculation of area overestimates the TA of a circle by 27% and is double the TA of a triangle. Additionally, there are concerns with the possibility of unpredictable human error in the measurement of wounds with rulers.
The manual l × w calculation of a square, circle, and triangle compared with the TA. Note that all shapes would calculate to 4 cm2 by l × w, despite their obvious differences in TA. A, area; r, radius; b, base; h, height.
Other more accurate devices utilized to measure the area of wounds are typically used in research trials. Planimetry uses a transparent film placed over the wound while the margins are traced. The investigator then calculates the area manually by counting the number of grid boxes filled or partially filled by the wound or the area is calculated by computer after digitally scanning the tracing.7
Digital imaging is a noncontact method using photography and computed area, which has been shown to be both accurate and have low interobserver variation.8
Three-dimensional wound measurement devices include stereophotogammetry,9
ultrasound measurement, and laser scanning.11
The ideal wound measurement device would be able to record irregular surfaces in a three-dimensional nontouch technique.9
While the ideal instrument does not exist, we have worked with several computer-based planimetric systems. The purpose of this study was to evaluate one of these devices as a “gold standard” to evaluate the differences in standard length by width wound measurements.