Can therapeutic ultrasound influence the integration of skin grafts?

Therapeutic ultrasound (TUS) is a widely used coadjuvant physical means to promote biological tissue repair. In the present investigation, the influence of TUS on the integration of full-thickness skin graft was studied in rabbits. Twenty female adult rabbits were used and two 2x2-cm square full-thickness skin grafts were obtained from both scapular regions and swapped, the one cut out on the right being placed on the left and vice versa. The graft on the right was irradiated with TUS (3 MHz, 0.5 W/cm2, 5-min duration) once a day for seven consecutive days, beginning on the third postoperative day; the graft on the left was submitted to simulated irradiation. The animals were killed on the 11th day and the grafted areas were resected (graft+safety margin) for histological examination. Five-mum-thick sections were alternatively stained with Gomori's trichrome, proliferating cell nuclear antigen (PCNA) and picrosirius red and examined under the light microscope, and the epidermal and dermal areas were measured and proliferating cells and new blood vessels counted. The results showed a significant increase (p=0.007) in the number of proliferating epidermal cells (12.18% and 7.34% of the total number of cells in the irradiated and control grafts, respectively) and new blood vessels per field (p=0.0001) in the irradiated grafts (6.27 compared with 3.07). Despite the increased number of proliferating cells and blood vessels, there was no significant difference between the epidermis (246,392 microm2 and 200,626 microm2 in groups 1 and 2, respectively; p=0.07) and dermis (2,157,730 microm2 and 2,109,150 microm2 in groups 1 and 2, respectively; p=0.21) areas as a function of thickness for both groups. We conclude that TUS induces morphological alterations in biological processes, such as epidermic germinative layer cell proliferation and neoangiogenesis, which are involved in the integration of full-thickness skin grafts. This has a potential for clinical use in humans.

Influence of therapeutic ultrasound on the biomechanical characteristics of the skin.

BACKGROUND: Skin function is dependent on its biomechanical characteristics, resistance, malleability, and elasticity. Therapeutic ultrasound may increase cutaneous malleability thus and optimize the rehabilitation process on specific diseases. The aim of this study is to evaluate possible alterations of biomechanical characteristics of the normal skin after therapeutic ultrasound application. METHODS: Thirty-one volunteers took part of the study, and the average age was 31.61 ± 8.37 years old. Biomechanical characteristics evaluation of the skin was performed with the Cutometer MPA 580 (Courage + Khazaka Electronic-Köln, Germany) of 2-mm probe hole and 500-mbar vacuum. Skin characteristics were analyzed before and after therapeutic ultrasound application, and the variables R0 (distensibility), R2 (gross elasticity), and R6 (viscoelasticity) were used for the study. Areas of therapeutic ultrasound application (continuous, 3 MHz, 1 W/cm(2) SATA) were defined at the upper limbs and standardized using a neoprene template. Sociodemographic data of volunteers were analyzed using SPSS 15.0. To analyze the distribution of the data, the Shapiro-Wilk test was used, which showed the normal distribution for R0 values, R2 and R6. For this procedure, the PROC TTEST from SAS® 9.0 software and Minitab 16 software, with significance, was set at the 0.05 level. RESULTS: In relation to R0, a significant increase (p = 0.001) was observed for the distensibility, when compared to values of pre- (0.3273 mm) and immediately post- (0.3795 mm) resource application which feature a greater distensibility. Related to R2 values, a significant increase (p = .001) of the gross elasticity at pre- (0.8419) and post- (0.8884) therapeutic ultrasound application was found. CONCLUSIONS: Therapeutic ultrasound promotes significant alterations of the biomechanical characteristics of the skin. TRIAL REGISTRATION: ClinicalTrials.gov, 1111-1146-7342.