Retrospective Review of Skin Laxity Improvement After a Single Acoustic Subcision Treatment for Cellulite Appearance

Abstract

BACKGROUND

Noninvasive acoustic subcision uses rapid acoustic pulse (RAP) treatment to disrupt subdermal and dermal fibrous tissue, thereby improving cellulite appearance. A prior multicenter study showed that 1 RAP treatment improved cellulite appearance 12 weeks after treatment.

OBJECTIVE

To evaluate whether treatment with acoustic subcision improved skin laxity appearance in participants with skin laxity seeking treatment for cellulite appearance.

METHODS AND MATERIALS

This retrospective study used images collected from a prior study that evaluated adult participants (n = 51) with severe cellulite on ≥1 thigh and/or buttock at baseline and 12 weeks after 1 RAP treatment. Outcomes included proportion of participants who achieved clinical improvement in skin laxity appearance via correct identification (≥60%) of blinded, randomized pretreatment and post-treatment photos; Global Aesthetic Improvement Scale (GAIS) responder rates (“improved” or “much improved”) for skin laxity by ≥2 of three physician reviewers 12 weeks post-treatment.

RESULTS

Among 51 participants, the mean age was 43 years. At least two of three physicians correctly identified 90.2% of photo sets (pretreatment vs week 12 post-treatment; 95% CI: 78.6%‒96.7%). GAIS responder rate was 80.4% (95% CI: 66.9%‒90.2%).

CONCLUSION

RAP treatment targeting cellulite also improved the appearance of skin laxity.

Cellulite is a common multifactorial aesthetic condition that primarily affects women and is characterized by skin irregularities overlying the gluteal and thigh region that result in a dimpled or rippled appearance.^1–3 The appearance of cellulite becomes more pronounced with age due to modifications in the skin structure, with the first changes evident around 30 years of age.⁴ Most of the dermal skin layer is made up of the extracellular matrix (ECM), which is produced and regulated by fibroblasts.^5,6 The ECM includes collagen and elastin, which are responsible for providing firmness, strength, and elasticity to the skin.^5,7 Age-related changes in the skin have a direct impact on homeostasis, resulting in a decrease in dermal thickness, fibroblast production, and collagen synthesis, as well as an increase in collagen and elastin fiber degradation.^8–10

Skin laxity, characterized by sagging or loose skin, occurs because of changes in elastin and collagen fibers, which results in the loss of skin elasticity and firmness.^5,11 Skin laxity is thought to be an aggravating factor in cellulite development.¹² With increased skin laxity, cellulite lesions become more evident and may appear in individuals not previously affected.¹² Older individuals have increased overall cellulite severity scores compared to younger individuals, indicating deeper depressed lesions and more severe raised lesions.¹³ Individuals with cellulite also exhibit earlier signs of skin aging, with increased laxity and reduced elasticity and retractability compared to individuals without cellulite.^14,15 With increased awareness of nonsurgical procedures for the treatment of cellulite and skin laxity, more individuals are seeking care from health care professionals.¹⁶

Noninvasive acoustic subcision treatment has demonstrated improvements in the appearance of cellulite.^17,18 High-frequency shockwaves delivered through the skin via proprietary Rapid Acoustic Pulse (RAP) technology treat the underlying causes of cellulite by disrupting subdermal and dermal fibrous tissue and promote the production of new collagen and elastin.¹⁹ A prior multicenter study determined that a single acoustic subcision treatment improved cellulite and skin laxity appearance.^17,18 At 12 weeks post-treatment, ≥90% of cellulite sites and 67.3% of laxity sites, regardless of baseline laxity severity, were graded as improved, much improved, or very much improved using the Global Aesthetic Improvement Scale (GAIS). In addition, 96.4% of post-treatment photographs were correctly identified by ≥2 of 3 reviewers.¹⁷ Results were consistent over a longer follow-up period; at 52 weeks post-treatment, the reviewers correctly identified 95.2% of post-treatment photographs.¹⁸

In previous studies examining devices for skin laxity improvement, the percentage of improvement has consistently been calculated only among patients who initially presented with skin laxity.^20–24 This selective approach ensures that the outcomes accurately reflect the device's efficacy in patients with the specified condition, allowing for meaningful interpretation and comparison across studies. In the authors' initial analysis, however, all patients—whether they had skin laxity or not—were included when calculating the improvement percentage, which yielded lower improvement rates. To provide results that align with the methodology of established studies, the authors reanalyzed the authors' data and only included those patients who initially presented with skin laxity. This approach enables the authors' findings to be accurately compared with similar studies in the literature. Thus, the objective of this study was to evaluate whether acoustic subcision improved skin laxity among participants who had skin laxity at baseline and were seeking treatment to improve the appearance of cellulite.

Materials and Methods

Study Design

This was a retrospective, blinded independent assessment of images collected during a multicenter, prospective study of the safety, efficacy, and tolerability of acoustic subcision treatment for improvement in the appearance of cellulite from July 2019 through December 2020. The study conformed to the ethical guidelines of the 1975 Declaration of Helsinki. The prospective study methods have been described previously.¹⁸ Briefly, participants in the prospective study included adult females with severe cellulite on ≥1 thigh and/or buttock at baseline with a stable weight for ≥6 months, a body mass index (BMI) ≤30 kg/m², no invasive or energy-based cellulite treatment within the previous 12 months, and no topical-based cellulite treatment within the previous 6 months.¹⁸ Two-dimensional photographs of the lateral, posterior, and posterior oblique views of participants' thighs and buttocks were collected using standard equipment at baseline and 12 weeks after acoustic subcision treatment.

Participants

Photographs from all participants in the prospective study who had images taken during baseline and week 12 visits were included for evaluation. The evaluable population consisted of all participants whose images were determined to have skin laxity (defined as loose and sagging skin) in ≥1 image group set (baseline or week 12 set containing three photographic angles) by all three board-certified dermatologists.

Photography Assessments

Three independent raters were selected from dermatologists practicing in the aesthetics field. The placement of each image group was randomized for each participant, and raters were blinded to participant identifiers, randomization assignment, visit number, and investigator name. For each participant, three slides were shown sequentially, each containing a baseline and week 12 image in one of the three angles. Raters were asked if the photograph groups show skin laxity and which of the two photograph groups represented the post-treatment photographs. Each rater also provided GAIS scores for participants identified with skin laxity.

Effectiveness End Points

The primary end point was the correct identification (≥60%) of blinded, randomized groups of pretreatment and post-treatment photographs, with respect to skin laxity, by at least two of three reviewers. An additional end point was the overall clinical improvement in the appearance of skin laxity at 12 weeks post-treatment, defined as a GAIS score of “improved” or “much improved” with respect to skin laxity for post-treatment photographs by ≥2 blinded raters.

Statistical Analysis

Frequency, proportion, and 95% confidence intervals (CIs) were tabulated for the proportion of participants who achieved clinical improvement in the appearance of skin laxity as assessed by correct identification of post-treatment photos and GAIS ratings. All effectiveness end point analyses were performed for the evaluable population, which consisted of all enrolled participants whose images were determined to have skin laxity in at least 1 image group set by all three raters.

Results

Participants

Photographs from 56 participants were included in the study; baseline and week 12 photographs from representative participants are shown in Figure 1. Five participants were evaluated by ≥1 rater as not having skin laxity, resulting in 51 participants for the analysis. The mean (SD) age and BMI of participants was 43 (6.7) years and 24.5 (2.8) kg/m², respectively, all participants self-identified as female.

Figure 1.

Baseline and week 12 photographs of three representative participants. (A) Participant was 48 years old, with a BMI of 30 kg/m², and received treatment on the left thigh and left buttock. (B) Participant was 28 years old, with a BMI of 22 kg/m², and received treatment on the left thigh and left buttock. (C) Participant was 45 years old, with a BMI of 23.2 kg/m², and received treatment on the left thigh and left buttock. All participants provided consent for image use for research, education, and informational purposes. BMI, body mass index.

Effectiveness: Skin Laxity Assessment via Blinded Reviewers

The primary end point was met for correct identification of week 12 post-treatment photographs regarding skin laxity by ≥2 raters; 90.2% of photograph groups were correctly identified by ≥2 of three raters, exceeding the 60% threshold (Figure 2). The GAIS responder rate was 80.4% (95% CI, 66.9%–90.2%), indicating that ≥2 blinded raters per photograph set determined skin laxity was “improved” or “much improved” at 12 weeks post-treatment (Figure 3).

Figure 2.

Percentage of raters who correctly identified baseline versus week 12 post-treatment photographs. Success was defined as at least 60% correct identification of the post-treatment photographs by ≥2/3 blinded, independent physician reviewers. To be included in the final analysis, participants must have been evaluated to have skin laxity by all 3 raters. CI, confidence interval.

Figure 3.

Proportion of participants with skin laxity ratings of “improved” or “much improved” on the investigator-assessed GAIS at 12-weeks post-treatment. GAIS, Global aesthetic improvement scale.

Discussion

In this retrospective photographic review, ≥2 of 3 blinded reviewers correctly identified post-treatment photographs among participants with skin laxity (n = 51) at baseline at a rate of 90.2%. A single acoustic subcision treatment also resulted in 80.4% of treated sites being graded as “improved” or “much improved” using the GAIS regarding skin laxity, as determined by ≥2 of 3 blinded reviewers.

Several other noninvasive treatments have been utilized to address concerns with skin laxity and/or cellulite, including radiofrequency (RF), lasers, and high-intensity focused ultrasound (HIFU). Treatment modalities such as RF and lasers use thermal energy delivered to the dermal and subcutaneous plane in the skin, triggering a wound-healing cascade that results in collagen remodeling and neocollagenesis, in addition to lipolysis.^25,26 In a 7-month retrospective study, participants treated with bipolar RF microneedling on their upper arms, bra-line, or suprapatellar area had a 95% improvement in both skin laxity and overall aesthetic appearance 3 months post-treatment; in addition, the mean (SD) pain score after treatment was 2.9 (1.7) on a scale of 0 to 10.²⁰ However, this procedure requires anesthesia and the pain patients perceived was higher than that reported after treatment via acoustic subcision (2.9 vs 0.3 on a scale of 0–10, respectively).

HIFU uses negative acoustic pressure to disrupt cell membranes and cause cell death, which leaves cavitation bubbles and disrupts cellulite structure to decrease dimpling.²⁷ The acoustic energy is converted to thermal energy, resulting in tissue injury. The tissue injury then stimulates neocollagenesis.²⁸ In a 12-week study utilizing this treatment modality for skin laxity on the abdomen and thigh, Ko and colleagues²⁹ found that 84.4% and 78.1% of participants were rated as improved or much improved, respectively, by independent raters using the GAIS. In addition, the mean (SD) pain score was 3.0 (1.6) immediately after treatment, which was higher than the mean pain score reported after acoustic subcision treatment.

Acoustic subcision delivers rapid acoustic pulses that disrupt the dermal and subdermal fibrous tissue and provide direct and indirect stimulation of the dermal fibroblasts, resulting in dermal remodeling and neocollagenesis.¹⁷ Acoustic subcision uses a novel mechanism of action to stimulate neocollagenesis through rapid acoustic pulses, rather than cavitation or thermal injury, minimizing the potential for pain.¹⁷ In porcine skin treated with acoustic subcision, a substantially greater amount of type II collagen was present 62 days post-treatment compared to baseline.¹⁷ Similarly, acoustic subcision–treated porcine skin showed a statistically significant induction of new collagen (type III; p < .001) and new elastin (p < .05) in the dermis.¹⁹ When comparing the current study to a previous acoustic subcision study evaluating the improvement in cellulite 12 weeks post-treatment, the GAIS responder rate was 80.4% versus 67.3% in Tanzi and colleagues.¹⁷ However, in the Tanzi study, participants who did not have laxity were included in the analysis, which could account for the lower GAIS responder rate.

One limitation of the study is that treatment was limited to only one visit, regardless of cellulite severity. Additional treatment visits may be more beneficial for patients with more severe cellulite; thus, further studies are needed to evaluate this possibility. Fitzpatrick skin phototype was not noted, which may limit the generalizability of the study findings. Finally, the lack of objective skin laxity measurements and the use of photos, rather than live or video evaluations, limits the ability to standardize skin laxity severity and assessment when determining the level of improvement after acoustic subcision treatment. For these reasons, future consideration should be given to utilizing video or live evaluation for skin laxity assessment.

Conclusion

A single acoustic subcision treatment improved the appearance of skin laxity in conjunction with improvement in the appearance of cellulite. Given the early findings in animal studies, future studies are needed to evaluate the mechanism of action of rapid acoustic pulse treatment in neocollagenesis.