Experimental Study of Skin Contraction Induced by Bipolar Radiofrequency.

Background: Facial skin relaxation has become an important part in solving the problem of facial rejuvenation. Minimally invasive or noninvasive skin-tightening procedures have become a trend for facial rejuvenation. Bipolar radiofrequency (RF) is a new option for treating skin relaxation and is more effective than noninvasive surgery without surgical incision.

Objective: To explore the effect of different bipolar RF powers on the area of the original box, changes of skin and subcutaneous tissue thickness and numbers of fibroblasts in rabbits.

Design: The research team performed an animal study.

Setting: This study took place in Affiliated Hospital of Nanjing University of Chinese Medicine.

Participants: Eighteen common-grade adult New Zealand rabbits (female, 2.5-3.0 kg).

Methods: Bipolar radiofrequency therapy was given to a girl rabbit on the left side of the treatment area. Standard HE and Masson staining were performed to assess the pathological changes, area of the original box and the number of fibroblasts in skin and subcutaneous tissues.

Outcome measures: (1) The area of the original box, changes of skin and subcutaneous tissue thickness, and numbers of fibroblasts under different bipolar RF temperatures or under different bipolar RF powers immediately after surgery, 1 month after surgery and 3 months after surgery were observed. (2) Standard HE and Masson staining results.

Results: Under the condition of certain instrument power, at 36de 38d and 40nd the area of the original box shrank to different degrees immediately after surgery (16.54±0.37, 17.78±0.03, 17.19±0.01), 1 month after surgery (16.59±0.31, 17.82±0.01, 18.34±0.30) and 3 months after surgery (16.89±0.12, 18.16±0.14, 19.23±0.32) compared with that before surgery (P < .05). Under specific temperature conditions, at 16 W, 18 W, 20 W, and 22 W, the area of the original box shrank to different degrees immediately after surgery (16.40±0.49, 15.55±0.57, 17.54±0.12, 16.19±0.27), 1 month after surgery (16.88±0.12, 17.46±0.02, 18.05±0.35, 19.41±0.08) and 3 months after surgery (19.09±1.01, 18.30±0.69, 20.00±0.29, 21.20±0.90) compared with that before surgery (P < .05). When the power was fixed, the thickness of skin and subcutaneous tissue decreased immediately after surgery (6.7, 6.8, 7), 1 month after surgery (6, 6.1, 6.3) and 3 months after surgery (6.4, 6.5, 6.2) at different temperatures (P < .05). When the temperature was fixed, the thickness of skin and subcutaneous tissue decreased immediately after surgery (6.1, 6.08, 6.03), 1 month after surgery (6.2, 6.15, 6.13), and 3 months after surgery (6.2, 6.23, 6.03) under different powers (P < .05). Under the condition of certain instrument power, at 36de 38d and 40n, the number of fibroblasts increased to different degrees immediately after surgery (26.54±2.37, 30.78±3.03, 37.19±4.01), 1 month after surgery (28.59±2.31, 34.82±3.01, 40.34±4.30), and 3 months after surgery (30.89±0.12, 38.16±0.14, 42.23±0.32) compared with that before surgery, and all were statistically significant (P < .05). Under specific temperature conditions, at 16 W, 18 W, 20 W, and 22 W, the number of fibroblasts increased to different degrees immediately after surgery (28.29±2.49, 30.97±3.57, 38.74±3.12, 45.68±4.27), 1 month after surgery (30.88±3.12, 32.46±4.02, 41.05±0.35, 50.41±0.08), and 3 months after surgery (29.99±2.01, 33.30±2.69, 39.00±3.29, 23.20±2.90) compared with that before surgery, and all were statistically significant (P < .05).

Conclusions: Our study clarifies that bipolar RF can decrease the skin and subcutaneous tissue thickness and increase the numbers of fibroblasts at the temperature of 36°C, 38°C, and 40°C and frequency of 16-22 W, which has a therapeutical effect on skin contraction. Our study might effectively improve the skin slack of patients, and the postoperative maintenance rate is high, and will not cause obvious complications. This study may provide a theoretical direction for clinicians to tighten the skin of patients using bipolar RF.