Reduction of Adipose Tissue and Improvement of Skin Laxity Using Combined PDLLA, Ultrasound, and Radiofrequency: A Prospective Case Series

Introduction

In recent years, non-invasive body contouring procedures have gained popularity as asafer and more convenient alternative to surgical options [1]. While liposuction remains a commonly performed cosmetic surgery, it carries significant risks and requires a lengthy recovery period, potentially leading to asymmetrical results. To address these limitations, various noninvasive modalities have been developed, such as cryolipolysis, radiofrequency, focused ultrasound, laser energy, and highintensity focused electromagnetic technology [2,3]. These techniques have become increasingly sought after due to their safety profile, minimal recovery time, and reduced cost.

Ultrasound-based technology utilized in body contouring procedures can induce adipose disruption via thermal coagulation or mechanical effects, depending on frequency and delivery mode.

High-frequency US generates heat that induces coagulative necrosis of adipocytes, leading to their destruction, and also stimulates collagen remodeling within the tissue matrix [4]. Notably, maintaining tissue temperatures above 56°C facilitates the necrotic process while preserving the integrity of surrounding nerves and vessels [5]. By effectively targeting both fat cells and collagen, this approach brings about gradual skin tightening and reduction of adipose tissue [5]. Focused US, on the other hand, utilizes low-frequency US to mechanically disrupt the adipocytes without relying on thermal effects [4,6]. These ultrasoundbased procedures selectively target adipose tissue while sparing surrounding tissue, nerves and blood vessels. This targeted approach helps minimize damage to non-targeted structures and reduces the risk of complications.

Radiofrequency (RF) technology for body contouring is a noninvasive procedure that utilizes RF energy to target and modify adipose tissue, resulting in body shaping and tightening effects [7,8]. First, RF energy penetrates the skin and heats the adipose tissue without causing damage to the epidermis. This selective heating effect is achieved by the preferential absorption of RF energy by water molecules in the adipose tissue and promotes the breakdown of fat cells, reducing their volume. Secondly, the heating effect promotes collagen production and remodeling within the skin and underlying tissue.

Recent approaches have explored the synergistic combination of US and RF for treating subcutaneous fat9. In this co-treatment a synergistic effect had been proposed, the acoustic pressure caused by the ultrasound selectively destroys adipocytes, while RF increases local metabolism to expel fat cell remnants while promoting collagen contraction and skin tightening [9,10]. Preliminary data show that this treatment is safe and efficiently reduces abdominal fat [10].

In parallel, biostimulatory fillers such as PDLLA have gained attention for their ability to induce collagen synthesis and restore structural support. Subdermal fillers allow the restoration of volume loss by filling the area concerned, correcting wrinkles, and improving body and facial contours. The number of cosmetic procedures with subdermal fillers has risen from 1.6 million in 2011 to 3.4 million in 2020. The types of off-the-shelf fillers include Hyaluronic Acid (HA), Calcium hydroxylapatite (CaHA), Poly-L-lactic acid (PLLA), and Polymethylmethacrylate (PMMA) [9-12]. Lenisna is a hybrid filler comprised of HA and PDLLA. HA draws in moisture for visibly plumper skin, while PDLLA stimulates collagen production in the skin. Upon injection, the PDLLA particles replace lost collagen and reinforce the skin structure. Over time, the appearance of fine lines and wrinkles will decrease as the skin’s collagen levels rise.

Buttock augmentation improves the volume, shape, and contour of the buttocks through fat grafting, silicone implants, or a combination of these two. However, these procedures often require anesthesia and carry serious risks. The only nonsurgical buttock augmentation treatment currently available is Sculptra, a dermal filler based on PLLA. However, the procedure requires 2-3 injections; results are visible only after 4-6 months and are temporary. Furthermore, the average cost of this treatment is high.

The present study evaluates a multimodal treatment strategy combining PDLLA injection with subsequent US and RF therapy for non-invasive buttock contouring.

Methods

Ten healthy female patients that presented an excess of local adipose tissue and skin laxity at the buttocks area and desired to tighten gluteus skin and were able to comply with all requirements of the protocol were treated at the Elite Laser Clinic, Madrid, Spain. Exclusion Criteria included pregnancy, current anticoagulant therapy, previous treatments in the area intended for treatment.

Data collection and management were carried out in compliance with applicable data protection regulationsAll patients provided written consent.

Protocol: At baseline, each patient was injected with one vial of Lenisna (Poly-D,L-lactic Acid+HA, Raum Medical, Seoul, Korea) on each side of the buttocks. Six weeks following the PDLLA injection, treatments with Alma Prime X (Alma Lasers, Caesarea, Israel) were initiated. Patients underwent three treatment sessions at 2-week intervals. Each subject completed a study schedule including screening, baseline, treatment, and follow-up visits. Ultrasound was administered using the UltraWave applicator (Alma Lasers, Caesarea, Israel) with a power levels of 5-8 W, with an operating frequency of 10 Hz, and high vacuum, for 15 min per session. This was followed by RF treatment, using the Unibody applicator for 15 minutes delivering a cumulative energy of 70 kJ at power levels ranging from 140 to 200 W in sub-deep or deep modes.

Outcome Measures: Each subject was evaluated at baseline and at three months following the final treatment session.

Treatment efficacy was measured using the following:

Subject-reported outcomes: Changes in buttock appearance as perceived by the subject at the three months follow-up visit using a Likert-scale of 1 to 5 (not satisfied, little satisfied, moderately satisfied, quite satisfied, very satisfied).

Fat layer thickness: Quantitative assessment using ultrasound (echography) with a 6-18 MHz linear probe (Mylab Class C, Esaote). Images were obtained at baseline and at the three-month follow-up visit.

Subcutaneous tissue elasticity: Evaluation by elastography using a 6-18 MHz linear probe. Images of the area in each patient at baseline and at the three-month follow-up visit. Tissue was graded on a 4-point scale: 1 (green, highest elasticity, soft) to 4 (red, lowest elasticity, hard): 4 (red)/3 (orange)/2 (blue)/1 (green).

Safety was monitored by recording adverse events during the treatment course and the follow-up period.

Patient satisfaction was recorded at follow-up using a 5‐point Likert scale: (1) very satisfied, (2) somewhat satisfied, (3) neutral, (4) somewhat dissatisfied, and (5) very dissatisfied [13].

Results

This case report series consisted of 10 female patients with a mean age of 45.6 ± 6.4 years. Outcomes were assessed by comparing baseline measurements with those obtained at three months following the final treatment session.

Ultrasound evaluation demonstrated a reduction in fat layer thickness in all patients, with a mean decrease of 54.0 ± 6.96% (p < 0.001). The areolar fat layer thickness decreased by 54.2 ± 9.46% (p < 0.001), while the lamellar fat layer thickness decreased by 52.5 ± 11.84% (p < 0.001) (Table 1, Figure 1).

Elastography findings indicated improvement in tissue elasticity, with the lamellar layer showing a 67.5 ± 12.08% improvement and the areolar layer a 55.0 ± 15.8% improvement (both p < 0.001) (Table 2, Figure 2).

Patient satisfaction scores ranged from 3 to 5, with a mean of 3.9 ± 0.7 (Table 2). Representative clinical images are presented in Figures 3, 4.

No adverse events were reported during the treatment or follow-up period.

Table 1: Changes in fat layer following treatment.

Table 2: Changes in fat layer elasticity following treatment and patient satisfaction.

Figure 1: Example of fat layer measurements captured by echography with a 6-18 MHz linear probe (Mylab Class C, Esaote). Images of the area in each patient at baseline (left) and at the follow-up visit three months after the last treatment session (right). Crosses mark the Areolar and Lamellar fat layers.

Figure 2: Examples of subcutaneous elasticity appearance captured by elastography with a 6-18 MHz linear probe. Images of the area in each patient at baseline (left) and at the follow-up visit three months after the last treatment session (right). Hardness scale from 1 (minimum) to 4 (maximum): 4 (red)/3 (orange)/2 (blue)/1 (green).

Figure 3: Patient photos of patient #4 pre-treatment (left) and at the follow-up visit three months after the last treatment session (right). This patient had a decrease of 56% in fat layer measurements and an increase of 50-75% in elasticity. She rated her patient satisfaction at 4 (out of 5).

Figure 4: Patient photos of patient #5 pre-treatment (left) and at the follow-up visit three months after the last treatment session (right).

This patient had a decrease of 43% in fat layer measurements and an increase of 50-75% in elasticity. She rated her patient satisfaction at 5 (out of 5).