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Cosmetic: Original Articles

Microneedling of Scars: A Large Prospective Study with Long-Term Follow-Up

Alster, Tina S. M.D.; Li, Monica Ka Yi M.D.

Author Information
Plastic and Reconstructive Surgery: February 2020 - Volume 145 - Issue 2 - p 358-364
doi: 10.1097/PRS.0000000000006462



The authors of the February 2020 Cosmetic article titled “Microneedling of Scars: A Large Prospective Study with Long-Term Follow-Up” (Plast Reconstr Surg. 2020;145:358–364) wish to make the following correction: The abstract misstated the number of study patients in the Background section as “20.” The correct number of patients is “120.” The corrected text should read as follows:

Background: In recent years, microneedling has been increasingly used to treat a number of dermatologic conditions, including scars. Although initial studies demonstrated improvement of (mostly) atrophic scars with microneedling, the number of patients evaluated was relatively small, and the devices and treatment protocols used and posttreatment follow-up varied widely. Through this prospective observational study, the results of microneedling on 120 patients with a variety of scars are described.”

Plastic and Reconstructive Surgery. 145(5):1341, May 2020.

Microneedling has gained popularity over the past several years for the noninvasive treatment of a broad range of cutaneous applications, including rhytides, acne scarring, dyschromia, and transdermal drug delivery.1 There are several different microneedling devices available, including fixed needle rollers and electric-powered pen devices with disposable sterile tips, each of which creates numerous epidermal and dermal microwounds to stimulate collagen remodeling. The controlled skin injury stimulates the dermal wound healing cascade (inflammation, proliferation, and remodeling) that leads to the release of platelet-derived growth factor, fibroblast growth factor, and transforming growth factor (TGF)-α and TGF-β.2,3 Neovascularization and neocollagenesis occur secondary to fibroblast proliferation and migration.4

Histologic study of burn scars treated with microneedling revealed increased reticular dermal collagen deposition with normal lattice architecture; increased deposition of elastic fibers; and a thickened epidermis with granular layer hyperplasia, normal stratum corneum, and rete ridges.5 The additional finding that microneedling up-regulates TGF-β3 over TGF-β1 and TGF-β2 (the latter responsible for fibrotic scarring) further justifies its use for scar treatment.2

Although more publications have outlined the use of microneedling for acne scarring than for any other skin condition,6–16 a variety of different protocols have been advocated, and an analysis of the effect of microneedling on different scar types has not been conducted on a large patient population. This prospective analysis of 120 patients who received microneedling treatment for a variety of facial and nonfacial scars with extended (6 to 12 months) clinical evaluation was conducted to provide further information about the degree and longevity of clinical responses that can be achieved with the modality.


One hundred twenty consecutive patients (101 women and 19 men) received microneedling treatment at a single center. Inclusion criteria included any facial and/or nonfacial scars secondary to acne, trauma, or surgery; any age as long as informed consent could be provided for the study; and those who were not receiving concomitant therapies with the microneedling intervention. Patients ranged in age between 14 and 78 years (average, 47.5 years) and exhibited a wide range of skin phototypes (I through VI) (Table 1). Exclusion criteria (for purposes of analysis) were if the scars were less than 6 months’ duration, previous scar treatments had been obtained within 6 months of initial microneedling application, permanent filler injections to scars had been received at any time, or if follow-up after treatment was less than 6 months.

Table 1. - Patient/Scar Demographics
Scar Type and Location No. Sex Mean Patient Age (Range) (yr) Skin Phototype
Women (%) Men (%) Women Men I II III IV V VI
Acne 75 61 (51) 14 (12) 49 (23–74) 45 (28–70) 11 31 22 7 3 1
 Face 72 58 14 50 (23–74) 45 (28–70) 11 29 22 7 2 1
 Body 3 3 0 34 (26–40) 0 2 0 0 1 1
Traumatic 20 18 (15) 2 (2) 44 (14–67) 30 (16–44) 2 15 2 0 1 0
 Face 11 10 1 49 (23–67) 16 1 9 1 0 0 0
 Body 9 8 1 36 (14–53) 44 1 6 1 0 1 0
Surgical 25 22 (18) 3 (2) 51 (18–78) 36 (23–44) 3 15 4 1 2 0
 Face 13 12 1 56 (18–78) 44 (44) 2 6 1 1 2 0
 Body 12 10 2 47 (18–76) 32 (23–41) 1 9 3 0 0 0
Total 120 101 (84) 19 (16) 48.5 (14–78) 42 (16–70) 16 61 28 8 6 1

Before treatment, all makeup or other debris was removed from the skin’s surface with a gentle cleanser. Topical anesthetic cream (compounded 30% lidocaine in an aqueous cream base) was then applied to the treatment areas without occlusion for 20 to 30 minutes. The cream was removed with water-soaked gauze and prepared with alcohol or hypochlorous acid (Lasercyn; Intraderm Pharmaceuticals, Petaluma, Calif.) immediately before treatment.

All scars were treated with a handheld motorized microneedling device (Collagen P.I.N.; Induction Therapies, Louisville, Ky.) by a single operator (T.S.A.). The device had been routinely used in the practice to deliver microneedling treatments for 24 months before study initiation. Sterile disposable needle cartridges (30-gauge, 36-needle array) were used at needle depths ranging from 2.5 to 3 mm. The deeper dermal depths were selected in an attempt to achieve maximal dermal collagen synthesis. The device was operated with battery power for virtually all treatments with the speed fixed at 13,500 rpm.

Hyaluronic acid gel (HA Glide; Induction Therapies) was applied on the scars to facilitate gliding action of the microneedling device during treatment. Gentle traction of the skin with one hand while simultaneously applying the microneedling tip perpendicular to the scar(s) with the other hand assisted with the smooth delivery of microneedles into the skin. A combination of horizontal, vertical, and oblique device passes over the treatment areas were delivered until uniform pinpoint bleeding was observed (range, four to 10 passes). Ice water–soaked gauze was applied to the treated areas to remove excess hyaluronic gel and achieve hemostasis. A thin layer of soothing balm (A Method Soothe HC; Induction Therapies) was applied to the treatment regions.

Patients were instructed to gently clean the areas twice daily with a mild cleanser (A Method Cleanse; Induction Therapies) followed by application of soothing balm and a mineral sunblock with sun protection factor 30 (A Method Protect SPF 30; Induction Therapies). Ice or cool water compresses were advocated on an as-needed basis. For facial scars, application of makeup was permitted 1 to 2 days after treatment, and regular skin care products were resumed in 1 week (on resolution of skin erythema). Patients with a history of labial herpes simplex who received treatment for scars in the perioral region were provided with a 7-day prophylactic course of twice-daily oral valacyclovir beginning immediately after treatment. Patients did not apply any topical scar treatments throughout the duration of the study. Patients returned for evaluation and additional microneedling treatments at monthly intervals until scar resolution and/or desired clinical improvement had been attained.

Photographs of scars were obtained at baseline; before each treatment session; and 1, 3, 6, and 12 months after the final treatment session using identical lighting and patient positioning. Two trained assessors blinded to the treatment protocol independently rated clinical improvement of scars on a five-point scale (Global Assessment Score) (0 = no change, 1 = 1 to 25 percent improvement, 2 = 26 to 50 percent improvement, 3 = 51 to 75 percent improvement, and 4 = 76 to 100 percent improvement) (Table 2). The assessors were trained medical assistants in the practice who were blinded to the study protocol and were not present when the microneedling treatments were delivered. The Global Assessment Score was determined by comparing photographs of clinical outcomes at different treatment time points to baseline. Side effects were monitored and tabulated. At the final follow-up visit, patients were asked to complete a satisfaction survey.

Table 2. - Global Assessment Scores
Score Degree of Improvement (%)
0 0
1 1–25
2 25–50
3 51–75
4 76–100


Patients received one to six consecutive monthly microneedling treatments (average, 3.2) (Table 3). Twenty-four percent of patients opted to discontinue further therapy after one treatment because of their satisfaction with treatment outcomes, with a mean Global Assessment Score of 2.27. Progressive clinical improvement was observed with each successive treatment. All scars improved at least 50 percent after an average of 2.5 treatments (mean improvement score, 3.07). There was a trend of higher Global Assessment Score after four to six treatments (Figs. 1 through 4). Over 80 percent of patients had 50 to 75 percent improvement and 65 percent of patients demonstrated over 75 percent improvement.

Table 3. - Clinical Results
Scar Type and Location No. Mean Global Assessment Scores (No. of Patients)
Treatment 1 (%) Treatment 2 (%) Treatment 3 (%) Treatment 4 (%) Treatment 5 (%) Treatment 6 (%)
Acne 75 14 17 12 11 6 15
 Face 72 2.7 (13) 2.8 (15) 3.1 (12) 3.7 (11) 3.8 (6) 3.5 (15)
 Body 3 2 (1) 2.5 (2)
Traumatic 20 11 2 2 2 2 1
 Face 11 2.3 (6) 2 (1) 3 (2) 3 (1) 4 (1)
 Body 9 1.8 (5) 3 (1) 3.5 (2) 4 (1)
Surgical 25 4 3 7 5 1 5
 Face 13 2 (1) 4 (1) 3.5 (4) 3.7 (3) 4 (3)
 Body 12 1.3 (3) 2 (2) 3.3 (3) 3.5 (2) 4 (1) 3.5 (2)
 Mean 2.27 2.73 3.24 3.6 3.76 3.6
 No. 120 29 22 21 18 9 21
Global Assessment Score: 0 = no change, 1 = 1–25% improvement, 2 = 26–50% improvement, 3 = 51–75% improvement, 4 = 76–100% improvement.
*Total mean GAS = 3.07.

Fig. 1.:
Atrophic acne scars on the cheeks before (left) and 6 months after (right) two microneedling treatments. Global Assessment Score = 3.
Fig. 2.:
Traumatic scar on the arm before (left) and 6 months after (right) two microneedling treatments. Global Assessment Score = 3.
Fig. 3.:
Surgical scar on the nose before (left) and 6 months after (right) two microneedling treatments. Global Assessment Score = 4.
Fig. 4.:
Atrophic acne scars on the back before (left) and 6 months after (right) two microneedling treatments. Global Assessment Score = 3.

The subjects’ own assessments of scar improvement mirrored those of the masked assessors. Facial scars responded better after one treatment compared with nonfacial scars, but no significant clinical differences were observed in clinical responses of facial scars versus nonfacial scars when additional treatments were delivered. Interestingly, acne scars on the body appear to improve to the satisfaction of affected patients after only two microneedling treatments. In contrast, both facial and nonfacial surgical scars require more than two treatment sessions. Overall, no significant clinical differences were seen between treatment responses of atrophic acne, traumatic, or surgical scars. Similarly, equivalent scar responses were observed in different skin phototypes.

Side effects were limited to transient erythema and edema (average duration, 3 to 7 days) in all patients. Uncommon purpura formation (4.2 percent) and herpes simplex virus reactivation (2.1 percent) were experienced (Table 4). These sequelae were seen only with treatment of facial scars. All cases of purpura resolved within 1 week without further interventions. Subsequent herpes simplex virus reactivation was prevented with oral antiviral therapy (1 g valacyclovir twice daily for 1 week). No dermatitis, skin dyspigmentation, scar worsening, or other short- or long-term adverse sequelae were observed. Patient skin phototype did not affect clinical outcome or the occurrence of adverse events.

Table 4. - Side Effects
Scar Location Erythema Dyspigmentation Purpura HSV
No. of Patients No. of Sessions No. of Patients No. of Sessions No. of Patients No. of Sessions No. of Patients No. of Sessions
Face 96 315 0 0 4 6 2 2
Body 24 64 0 0 0 0 0 0
HSV, herpes simplex virus.


The presence of scars can have significant physical and psychosocial implications for those affected. A wide variety of surgical techniques and energy-based treatments have been used to successfully improve scars17–19; however, access to these treatments may be limited and the treatments themselves are often costly and associated with further risk of scarring.20,21 Scar treatments in patients with dark skin are further complicated by the risk of undesirable dyspigmentation, particularly with the use of lasers because of heat production during skin irradiation.22

The results obtained in this study support the use of microneedling for acne, traumatic, and surgical scars, with minimal risk of untoward side effects across a wide range of skin phototypes and body locations. Clinical responses seen in the study correlate to previously published observations.5,6,9,11,14,15 No serious adverse events occurred, and side effects were minimal and transient. Similar to laser skin resurfacing treatment,23 microneedling has been shown to promote neocollagenesis and scar remodeling through dermal wounding. The full clinical effect may take several months to be realized, as new collagen deposition takes place gradually. Dissimilar to laser treatment, there is no thermal injury to the skin with microneedling, thus reducing the risk of postinflammatory dyspigmentation—a particular advantage when patients with darker skin phototypes are seeking treatment.24

Strengths of this study include the large patient cohort, the variety of scars and locations treated, the wide range of skin phototypes, and the long follow-up assessment. It is one of only a handful of studies that have been performed using a motorized microneedling device (rather than a roller-type device) on scars.

A major limitation of this study was the lack of controls and/or a comparison treatment group. However, other groups have already shown comparable clinical results when nonablative fractionated lasers were compared to roller-type microneedling devices, with fewer side effects and shorter recovery times noted after microneedling treatment.25,26 In addition, this study did not address the concomitant use of other treatments such as platelet-rich plasma,27–29 topical acids,30–34 fillers,35,36 or radiofrequency37—each having shown clinical efficacy in prior publications.


Microneedling is a simple, inexpensive treatment for atrophic, traumatic, and surgical scars that yields clinically significant and longstanding improvement. Its advantages include rapid posttreatment healing and minimal side effects. This study is the first large-scale, long-term evaluation using a motorized microneedling device for treatment of facial and nonfacial scars of different causes across a wide range of skin phototypes. Its clinical efficacy mirrors that reported with various skin resurfacing lasers and corroborates the prolonged clinical improvement reported with roller-type microneedling devices. Further studies will help to establish standardized protocols to optimize treatment outcomes for different scar types and determine whether combination treatments provide additional therapeutic benefit.


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