Research article

Nonlinear modeling of venous leg ulcer healing rates

Matthew Cardinal¹ , Tania Phillips² , David E Eisenbud¹ , Keith Harding⁴ , Jonathan Mansbridge⁵ and David G Armstrong³

¹Advanced BioHealing, La Jolla, CA, USA

²Boston University School of Medicine, Boston, MA, USA

³Southern Arizona Limb Salvage Alliance (SALSA), Department of Surgery, University of Arizona, Tucson, Arizona USA

⁴Cardiff University School of Medicine, Wales, UK

⁵Tecellact, La Jolla, California, USA

author email corresponding author email

BMC Dermatology 2009, 9:2doi:10.1186/1471-5945-9-2

Published:	31 March 2009

Abstract

Background

The purpose of this manuscript was to determine whether the change in wound surface area over time could be described through nonlinear mathematics.

Methods

We studied 3,588 serial wound tracings of 338 venous leg ulcers (VLUs) that had been followed during a controlled, prospective, randomized trial of two topical wound treatments.

Results

A majority (72%) of VLUs exhibited surface area reduction via an exponential decay model, particularly during the early stages of healing. These results were consistent with the mechanics of wound contraction and epithelial cell proliferation, supported by the higher frequency at which exponential surface area reduction associated with full wound closure (35% of wounds that fit the exponential model healed vs. 21% of wounds that did not fit the exponential model completely healed during the study period, p = 0.018). Goodness-of-fit statistics suggested that much of the individual variation in healing could be described as nonlinear variation from the exponential model.

Conclusion

We believe that parameter estimates from a mathematical model may provide a more accurate quantification of wound healing rates, and that similar models may someday reach routine use in comparing the efficacy of various treatments in routine practice and in product registration trials.