Histological and clinical dose-response analysis of radiofrequency microneedling treatment for skin rejuvenation.

Radiofrequency microneedling (RFMN) is a commonly used fractional device to treat skin laxity and rhytids. Several studies investigated its histological and clinical effects. However, the role of the applied energy per needle (EPN) and total energy in the outcome remains unclear. The aim of the present study is to analyze the correlation between applied energy and resulting histological and clinical volume effects of RFMN treatment for skin rejuvenation. Ex vivo porcine skin was treated with a RFMN system equipped with insulated needles. Histological measurements of coagulation volumes were correlated with the delivered EPN, ranging from 20 mJ to 100 mJ. For the clinical investigation, a cohort of patients received treatment on the lower face and submental area. Absolute volume changes were calculated using computer-aided three-dimensional analysis. Pearson's and Spearman's correlation coefficients r were determined. Histologic analysis revealed a strong positive correlation between EPN and coagulation volume (r = 0.976; p < 0.005). A total of 30 patients, with a mean age of 55.9 ± 8.7 years, were recruited and received 1.7 ± 0.8 sessions (1-3) with a total energy of 1518.2 ± 784.1 J. Three-dimensional imaging revealed a strong logistic correlation with the total energy applied across all sessions (r = 0.676; p < 0.001). Analysis showed a positive association between the number of sessions and volume change. Study findings indicate a very strong and strong correlation between the applied energy and the resulting histological and clinical outcome in RFMN treatment, respectively. The introduction of coagulation volume as a matrix in RFMN treatments enables medical doctors to tailor and adjust treatment plan to the individual patient.