Med Lasers 2023; 12(4): 237-242
Skin tightening effecacy and safety: high-intensity focused ultrasound alone or in combination with monopolar radiofreqeuncy treatment in Republic of Korea: retrospective clinical study
Seo Koo Lee, Seung Min Nam, Han Gyu Cha, Eun Soo Park
Department of Plastic and Reconstructive Surgery, Soonchunhyang University Bucheon Hospital, Bucheon, Republic of Korea
Correspondence to: Eun Soo Park
Received: November 28, 2023; Accepted: December 18, 2023; Published online: December 22, 2023.
© Korean Society for Laser Medicine and Surgery. All rights reserved.

This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Background: High-intensity focused ultrasound (HIFU) and monopolar radiofrequency (RF) are used for facial rejuvenation. Both modalities are popular non-invasive skin tightening and wrinkle reduction procedures and are implemented autonomously or in combination. However, their synergic effectiveness remains to be determined.
Methods: Thirty-six patients treated for skin wrinkles by HIFU or HIFU plus monopolar thermal RF between August 2021 and August 2023 were enrolled in this study. An automatic skin diagnosis system was used to evaluate treatment efficacies, and a blinded clinician assessed clinical photos. Safety and patient satisfaction were also investigated.
Results: Twenty patients received HIFU monotherapy (Group A) and 16 simultaneous HIFU plus monopolar RF (Group B). An automatic skin analysis system showed that both techniques achieved significant wrinkle improvement. However, Group B had better clinical assessment and patient satisfaction scores. Observed adverse effects, which included erythema and swelling, were mild and self-limiting.
Conclusion: Combined HIFU and RF constitute a safe non-invasive procedure that effectively improves facial wrinkles and skin laxity.
Keywords: HIgh-intensity focused ultrasound; Radiofreqeuncy; Skin aging

Facial wrinkles are not merely indicative of the natural aging process but are also perceived as undesirable features that cause significant concern for many individuals [1]. While traditional solutions have involved surgical approaches to address these concerns, a variety of reasons render surgical interventions impractical or unfeasible for certain individuals. Consequently, noninvasive modalities have garnered increasing attention as preferred alternatives to mitigate the appearance of facial wrinkles. Recently, noninvasive methods such as lasers, light therapy, and ultrasound have been designed and employed for the treatment of skin wrinkling and sagging [2,3].

While ultrasound is more commonly known as a diagnostic tool, it has found significant utility in the realm of face and body tightening using controlled high-intensity focused ultrasound (HIFU). Ultrasound applied through the skin to soft tissue in whole organs primarily causes coagulative necrosis through thermal mechanisms. This is achieved by generating heat through molecular friction in the ultrasound field, resulting in selective coagulative changes within the beam’s focal region while sparing adjacent tissue. This effect occurs at the deep dermis and superficial musculoaponeurotic system (SMAS) levels, leading to histological regeneration of dermal collagen and elastic fibers while increasing their numbers. It also induces thickening of the reticular dermis. Through this dermal collagen regeneration, rejuvenation can be achieved [2,4,5].

Radiofrequency (RF) technology operates by generating heat due to tissue resistance to electron movement within an RF field, resulting in coagulative necrosis. This effect is influenced by the depth of energy penetration and the varying resistance in soft tissue layers like dermis, fat, muscle, and fibrous tissue [6,7].

Both HIFU and Monopolar RF are widely used for facial rejuvenation. While research on the individual efficacy and safety of these two methods exists, there is a significant gap in the literature regarding the comparative or combined effects of these approaches. Therefore, we have planned this study to address this research gap.

Ethics statement: This study was approved by the Institutional Review Board (IRB) of the Soonchunhyang Medical Center Office of Human Research Protection Program (IRB no. 2023-11-004). It conformed to the Declaration of Helsinki. All subjects provided written informed consent.

A retrospective study was conducted on a total of 36 patients with facial wrinkles. Between August 2021 and August 2023, 20 patients were assigned to the HIFU monotherapy, Group A, while 16 patients were assigned to the Group B using both HIFU and monopolar RF. This assignment was based on the patients’ preferences and was not randomized.

Patients with local skin diseases, visible scars, or those who underwent other skin procedures during the follow-up period were excluded from the study. Clinical photographs of patients were taken before the procedure, and follow-up photos, through which an independent investigator evaluated the treatment’s effect, were captured about three months later. Demographic data, clinical information and complications were collected through chart review. Each treatment was performed following the manufacturer’s recommended protocol.

Facial wrinkles of the patients were assessed through an automatic skin analysis system (Mark-Vu®; PSI Plus Corp.). The machine scanned the front and both sides of the patient’s face to assess the degree of skin laxity and sagging, calculate and represent the percentage of shadow area caused by wrinkles relative to the measured area.

An independent investigator assessed the efficacy of the procedure. For each patient, pre- and postprocedure photos were randomly presented, and the independent investigator was asked to choose the postprocedure image. If the selection matched, it was considered as “effective.” If the evaluator chose the preprocedure photo or could not differentiate between the two, it was considered as “ineffective.”

Patient satisfaction was assessed through surveys after the follow-up period concluded. The clinician conducted a chart review to assess the presence of complications such as severe pain, edema, erythema, hypopigmentation, and hyperpigmentation, as well as to record the procedure duration.

Treatment protocol

Both groups received the topical anesthetic ointment (Emla®; Recipharm) applied 30 minutes prior to the procedure. Subsequently, they were cleansed with soap and water just before the procedure.

In the Group A, received one session of treatment with HIFU (10thera®; Tentech Inc.), two types of transducers were used. The 4-MHz, 4.5 mm depth transducers were applied at 0.7 J/mm2 on each side, with 80-90 shots. Additionally, the 7-MHz, 3.0 mm depth transducers were applied at 0.4 J/mm2 on each side, with 30-70 shots.

The Group B underwent RF (10therma®) treatment first, with an intensity of 3.0-2.5 J/mm2 and 200-300 shots applied to the entire face. Subsequently, the HIFU (10thera®) procedure was performed using 4-MHz, 4.5 mm depth transducers at 0.7 J/mm2 on each side, with 50-70 shots. Additionally, 7-MHz, 3.0 mm depth transducers were applied at 0.4 J/mm2 on each side, with 40-60 shots.

Statistical analysis

All statistical analyses were performed using Rex Excel-based statistical analysis software, ver. 3.6.0 (RexSoft, based on R ver. 3.6.3 (R Foundation for Statistical Computing). Statistical significance was considered when p-value was less than 0.05.


The study included a total of 36 patients, Group A consists of 20 individuals (17 females and 3 males), while Group B comprises 16 individuals (15 females and 1 male). There was no significant difference in age between the two groups (54.10 ± 12.20 years in the Group A, 53.12 ± 8.74 years in the Group B). The pretreatment wrinkle scores, evaluated using an automatic skin analysis system, also showed no statistically significant difference (17.88 ± 2.47 in the Group A, 17.85 ± 1.41 in the Group B; Table 1).

Table 1 . Comparison of patients with facial wrinkle receiving different treatment

CharacteristicGroup A (n = 20)Group B (n = 16)p-value
Male3 (15.0)1 (6.25)
Female17 (85.0)15 (93.75)
Age (yr)54.10 ± 12.2053.12 ± 8.740.7896
Pretreatment wrinkle score17.88 ± 2.4717.85 ± 1.410.9627

Values are presented as number (%) or mean ± standard deviation.

In each group, 17 and 13 individuals utilized the automatic skin analysis system to assess wrinkle scores before and after the procedure. The mean wrinkle score in Group A decreased from 17 (IQR, 16-19) to 15 (IQR, 14-16) (p < 0.01). While in Group B, it decreased from 18 (IQR, 17-19) to 14 (IQR, 13-16) (p < 0.01), which is greater than what was observed in the Group A (p = 0.7373; Fig. 1, Table 2).

Table 2 . The wrinkle scores

Wrinkle score
Group A (n = 17)17a) (16-19)15a) (14-16)<0.01
Group B (n = 13)18a) (17-19)14a) (13-16)<0.01

Values are presented as median (IQR).

a)p-value by Wilcoxon signed-rank test.

Figure 1. Improvement of wrinkle scores at pretreatment and posttreatment in each group. There was a statistically significant difference (p < 0.01).

The efficacy, assessed by independent investigator, showed “effective” results in 16 individuals (80.0%) for the Group A and 14 individuals (87.5%) for the Group B. Although the combination group exhibited a tendency for higher efficacy, the difference was not statistically significant (p = 0.5381; Figs. 2, 3).

Figure 2. The patient in Group A, an 80-year-old female, exhibited prominent wrinkles in the nasolabial area in the pretreatment photograph (A). In the posttreatment photograph after one session of high-intensity focused ultrasound treatment on the right side (4-MHz, 4.5 mm depth transducers, 164 shots, the 7-MHz, 3.0 mm depth transducers, 81 shots) (B), improvement in the wrinkles of the corresponding area was observed, with the wrinkle score decreasing from 23 to 17.

Figure 3. The pretreatment photograph of a 60-year-old female patient in Group B is shown in (A). In the posttreatment photograph after one session of high-intensity focused ultrasound and monopolar radiofrequency treatment (radiofrequency intensity of 2.5 J/mm2, 200 shots and 4-MHz, 4.5 mm depth transducers, 100 shots, the 7-MHz, 3.0 mm depth transducers, 100 shots) (B), overall improvement in wrinkles and a noticeable skin tightening effect can be observed, with the wrinkle score improving from 19 to 16.

Patient satisfaction was assessed on a scale of 1 to 10 at the end of the follow-up period. There was a statistically significant difference between 6.70 ± 1.53 for Group A and 7.62 ± 0.96 for Group B. (p = 0.0335; Fig. 4).

Figure 4. Comparison of patients’ satisfaction score. Mean value of the Group A was 6.70 ± 1.53, of the Group B was 7.62 ± 0.96, there was a statistically significant difference (p = 0.0335).

In the Group A, 14 patients experienced mild erythema and swelling immediately after the treatment, while two patients exhibited moderate erythema and swelling right after the procedure. However, all patients saw a complete resolution of both erythema and swelling within two days following the treatment. In the combination group of HIFU and monopolar RF, seven patients experienced mild erythema and swelling immediately after the procedure, while two patients had moderate erythema and swelling. However, like the HIFU group, all of these symptoms completely resolved within two days following the treatment. There were no other complications such as hypopigmentation, hyperpigmentation, or ulceration in any patient. There was no adverse event such as nerve or muscle dysfunction, severe pain, bruising, fat necrosis, or bleeding in both groups.


HIFU targets the SMAS layer to non-invasively create a thermal injury zone, promoting the regeneration of collagen and elastic fibers. RF has been relatively used for some time, and similarly, it utilizes heat generated by the resistance of tissue to the movement of electrons. It affects the diffuse area, promoting collagen regeneration.

There are differences in the effects based on the targeting layer, depth, and skin thickness between HIFU and monopolar RF. In the case of HIFU, it forms a thermal-induced coagulation zone in an inverted conical shape. The vertical depth of the coagulation zone varies depending on the probe, with the 4-MHz probe being approximately 4.5 mm and the 7-MHz probe around 3.0 mm [8]. Monopolar RF rather affects diffuse regions about 3 to 6 mm depth [9,10]. By utilizing these two modalities, it is possible to achieve skin tightening effects by concentrating on using devices that match the varying characteristics of layer depth for each individual and treatment area.

The diffuse bulking effect of RF demonstrated not only a wrinkle-specific impact but also pronounced overall skin tightening effect [11,12]. While this difference could be evident in the independent investigator assessments of effectiveness, it did not reach statistical significance.

Unlike other devices, the monopolar RF machine used in this study does not have a time lock function, which limits the usage time for a single cartridge, allowing the physician to arbitrarily adjust the number of shots used in a single session. This feature also serves as a strength in providing customized treatment based on the patient’s facial shape and the appearance of wrinkles.

The HIFU machine utilized in the research employed a two-line irradiating transducer, theoretically allowing for the same number of shots to be performed in a shorter duration. In our previous research, when utilizing the two-line HIFU, the average treatment time was approximately 11 minutes [13]. Also, employing 5 cm2 sized tip for monopolar RF, which is 25% greater than conventional probes, able to perform a procedure on a wide area within the same timeframe. This approach demonstrated statistically comparable effectiveness in terms of skin tightening and safety to other HIFU equipment. The use of this two-line HIFU provides a significant advantage in terms of treatment time, especially when combined with monopolar RF. It offers substantial benefits for simultaneous treatments.

According to the research findings, the simultaneous use of HIFU and monopolar RF did not significantly increase the incidence of severe complications. However, it is cautioned that avoiding areas where nerves pass is recommended, as stimulation in such areas may lead to pain and numbness. Similarly, procedures around the thyroid area should be avoided. For monopolar RF, the orientation of the probe during the procedure is crucial. The probe’s axis should be as close to 90 degrees to the skin as possible, and attention should be paid to bony contours and areas with prominent curvature during the procedure. Additionally, using an ample amount of coupling fluid is advisable. The sequence of performing the procedures, whether HIFU or RF, does not significantly impact the outcomes.

This study has several limitations. It may be limited by the relatively small number of cases, which falls short of the initially planned 20 cases per group. To obtain statistically significant data, it would be advisable to expand the sample size in future research.

Furthermore, since patient recruitment was not random but based on patient preferences for the treatment modality, the groups were divided accordingly. This introduces a potential selection bias that cannot be excluded, and it may impact satisfaction. Therefore, it is necessary to address and rectify this limitation in subsequent studies.

In conclusion, the comparison between the individual use of two modalities for improving skin wrinkles, HIFU and RF, and their simultaneous use revealed that the combined application resulted in a more effective outcome in skin tightening, demonstrating proven stability.




Conceptualization: SMN, ESP. Data curation: SKL. Formal analysis: SKL, HGC, ESP. Funding acquisition: ESP. Investigation: SKL, SMN. Methodology: SKL, HGC, ESP. Project administration: SKL, ESP. Software: SKL, SMN, ESP. Validation: SKL, ESP. Visualization: SKL. Writing–original draft: all authors. Writing–review & editing: all authors.


Eun Soo Park is an editorial board member of the journal, but was not involved in the review process of this manuscript. Otherwise, there is no conflict of interest to declare.


This work was supported by the Soonchunhyang University Research Fund.


Contact the corresponding author for data availability.

  1. Hess U, Huppertz D, Mauersberger H, Kastendieck T. Wrinkles are neither beautiful nor nice: the effect of facial wrinkles on person perception and interpersonal closeness. Acta Psychol (Amst) 2023;241:104077.
    Pubmed CrossRef
  2. Laubach HJ, Makin IR, Barthe PG, Slayton MH, Manstein D. Intense focused ultrasound: evaluation of a new treatment modality for precise microcoagulation within the skin. Dermatol Surg 2008;34:727-34.
    Pubmed CrossRef
  3. Pritzker RN, Hamilton HK, Dover JS. Comparison of different technologies for noninvasive skin tightening. J Cosmet Dermatol 2014;13:315-23.
    Pubmed CrossRef
  4. White WM, Makin IR, Barthe PG, Slayton MH, Gliklich RE. Selective creation of thermal injury zones in the superficial musculoaponeurotic system using intense ultrasound therapy: a new target for noninvasive facial rejuvenation. Arch Facial Plast Surg 2007;9:22-9.
    Pubmed CrossRef
  5. Park H, Kim E, Kim J, Ro Y, Ko J. High-intensity focused ultrasound for the treatment of wrinkles and skin laxity in seven different facial areas. Ann Dermatol 2015;27:688-93.
    Pubmed KoreaMed CrossRef
  6. el-Domyati M, el-Ammawi TS, Medhat W, Moawad O, Brennan D, Mahoney MG, et al. Radiofrequency facial rejuvenation: evidence-based effect. J Am Acad Dermatol 2011;64:524-35.
    Pubmed KoreaMed CrossRef
  7. Ruiz-Esparza J, Gomez JB. The medical face lift: a noninvasive, nonsurgical approach to tissue tightening in facial skin using nonablative radiofrequency. Dermatol Surg 2003;29:325-32. discussion 332.
    Pubmed CrossRef
  8. White WM, Makin IR, Slayton MH, Barthe PG, Gliklich R. Selective transcutaneous delivery of energy to porcine soft tissues using Intense Ultrasound (IUS). Lasers Surg Med 2008;40:67-75.
    Pubmed CrossRef
  9. Kreindel M, Mulholland S. The basic science of radiofrequency-based devices. In: Duncan DI, editor, Enhanced Liposuction - New Perspectives and Techniques. IntechOpen; 2021.
  10. Han SH, Yoon YM, Lee YW, Choe YB, Ahn KJ. Usefulness of monopolar thermal radiofrequency treatment for periorbital wrinkles. Ann Dermatol 2018;30:296-303.
    Pubmed KoreaMed CrossRef
  11. Wanitphakdeedecha R, Yogya Y, Yan C, Phumariyapong P, Nanchaipruek Y, Thongjaroensirikul P, et al. Efficacy and safety of monopolar radiofrequency for treatment of lower facial laxity in Asians. Dermatol Ther (Heidelb) 2022;12:2563-73.
    Pubmed KoreaMed CrossRef
  12. Weiss RA, Weiss MA, Munavalli G, Beasley KL. Monopolar radiofrequency facial tightening: a retrospective analysis of efficacy and safety in over 600 treatments. J Drugs Dermatol 2006;5:707-12.
  13. Kim SH, Lee SK, Cha HG, Park ES. Clinical utility of the 2-line high-intensity focused ultrasound for skin tightening in Republic of Korea: retrospective clinical study. Med Lasers 2023;12:29-33.

This Article

Cited By Articles
  • CrossRef (0)
  • Download (160)

Author ORCID Information

Funding Information


Social Network Service