Noncontact low-frequency ultrasound therapy in the treatment of chronic wounds: a meta-analysis.

Our objective was to summarize and quantify the effects of a noncontact low-frequency ultrasound (NLFU) therapy on healing of chronic wounds. We performed a meta-analysis of eight published studies reporting effects of NLFU on wound size and healing rate of chronic wounds in 444 NLFU-treated patients. A search of the PubMed database was conducted in January 2010 and updated in October 2010. We used random-effects linear regression models to estimate the proportional reductions in wound area and volume and the proportion of wounds healed from baseline to last follow-up. In four studies (N=188) reporting change in wound area from baseline, NLFU was associated with 85.2% area reduction (95% CI 64.7%-97.6%) over a mean 7 weeks. In four studies (N=278) reporting reduction in wound volume, NLFU was associated with 79.7% volume reduction (95% CI 46.1%-98.8%) over a mean 12 weeks. In seven studies (N=429) reporting proportion of wounds healing by study end (mean time to healing 8.2 weeks; median 6.8 weeks), meta-analyzed healing rates over time suggest 32.7% of wounds healed on average by 6 weeks (95% CI 23.3%-42.1%) and 41.7% by 12 weeks. NLFU for treatment of chronic wounds was associated with consistent and substantial wound size reductions, as well as favorable rates of healing.