Follicular Unit Excision in Patients of African Descent: A Skin-Responsive Technique

Supplemental Digital Content is Available in the Text.

Abstract

BACKGROUND

Follicular unit excision is a favored minimally invasive hair transplantation method. However, it is suboptimal for many patients of African descent because of wide variations in hair and skin characteristics.

OBJECTIVE

To evaluate the performance of a skin-responsive follicular unit excision device, which accommodates hair curliness, skin thickness, and firmness in patients of African descent.

MATERIALS AND METHODS

The authors retrospectively evaluated patients who underwent scalp follicular unit (FU) excision using a skin-responsive technique at 7 multinational clinics. The preoperative donor grading for the anticipated difficulty used a scale with Class V indicating the highest degree of hair curliness, skin thickness, and firmness.

RESULTS

Of 64 eligible patients (45 males and 19 females), 28 had Class V FU excision donor grades. The mean transection rate for all patients was 3%–6%, which was highest in class V patients. Skin thickness and firmness had a greater effect on the maximum transection rate than hair curliness. Only 19 or 18 G punches were used.

CONCLUSION

The authors report consistence success of a new skin-responsive FU excision device for all patients of African descent with a mean graft transection rate of less than 10%. The findings support skin thickness and firmness as major influencers of graft attrition rate.

Follicular unit excision (FUE) is a hair transplantation method preferred by men who choose a closely shaved head or crew cut because it is minimally invasive and avoids the linear scarring typical of other techniques.¹ Although men with Afro-textured hair have the least tolerance for linear scars because of their relative preference for shaved heads or shorter haircuts, they are often denied FUE based on the higher challenge that curled hair of African-descended patients poses to current FUE techniques relative to other ethnicities.^2–6 Furthermore, to reduce graft attrition rates, current FUE methodologies require larger punches,^3,4,6 resulting in larger wounds and scarring. This poses additional risks to African-descended individuals already prone to abnormal scarring.⁷

Because FUE surgery graft attrition rates may vary from one part of the head to another within the same individual^8,9 and the difficulty level may not correlate with hair-curl tightness,² skin thickness and firmness may play critical roles in FUE outcomes.² In addition, African-descended patients have diverse hair curl types and skin characteristics due to millennia of migration and gene mixing.^2,10 Thus, FUE techniques addressing hair and skin properties to limit negative outcomes in African-descended individuals are needed.^2,3

The authors retrospectively analyzed FUE data from African-descended patients at multiple multinational centers using a novel skin-responsive FUE technique¹¹ designed to overcome several factors contributing to graft attrition—such as tighter hair curliness and relatively higher scalp skin thickness and firmness.^2,5

Materials and Methods

All patients provided written informed consent for surgery and, when applicable, consent to publish photographs. All procedures were conducted following the Declaration of Helsinki (revised in 2013). An exemption from ethics approval was obtained from the Western Institutional Review Board (IRB) Copernicus Group.

Deidentified patient data were obtained from 7 independent hair restoration clinics in the United States, South Africa, Mexico, India, Colombia, and Brazil, which perform procedures on patients of African descent. Of 7 participating surgeons, 6 had an experience of at least 5 years and one had experience of 1 year in routinely performing FUE surgeries. Data from the lead author and developer of the technology and donor scoring scale used in this study were excluded to minimize bias. All patients of African descent who underwent scalp-hair-only FUE of more than 125 grafts between December 1, 2020, and December 15, 2022, using a skin-responsive FUE device (SRFD)—called the Dr. UGraft Zeus FUE device (Dr. U Devices, Manhattan Beach, CA)^11–13 (Figures 1 and 2A)—were included in this study.

Figure 1.

All-purpose skin-responsive FUE device: The skin-responsive FUE device shows a handpiece, foot pedal, and console with a dashboard highlighting the thick-firm scalp preset selection in yellow, and the torque and rotational speed (revolution per minute—RPM) dials. FUE, follicular unit excision; RPM, revolutions per minute.

Figure 2.

Second dashboard screen of the all-purpose skin-responsive FUE device showing 3 compound movement settings and adjustable millisecond durations of each movement (A) and close-up view of the all-purpose punch (B). FUE, follicular unit excision.

Preoperative Follicular Unit Excision Donor Assessment

The Sanusi FUE Scoring (SFS) scale was used to preoperatively assess the FUE donor area for the expected difficulty level.² The SFS scale, graded I–V, scores the scalp donor zone according to the expected difficulty posed by the FUE procedure based on a combination of skin and hair characteristics. Scores of 3 skin characteristics (thick, 6; thin, 4; medium, 1) were added to scores derived from hair characteristics (coily/kinky, 3; curled, 2; and straight/wavy, 1) for a total score range of 2 to 9. The latter was used to derive a class or grade of predicted increasing difficulty in proportion to the tallied score (2–3, Grade I, no difficulty, very low graft attrition rate; 4, Grade II, low-to-moderate difficulty, low-moderate graft attrition rate; 5–6, Grade III, moderate difficulty, susceptibility to graft decapping; 7–8, Grade IV, moderate-to-high difficulty, moderate-to-high graft attrition rate; and 9, Grade V, high difficulty, high-to-very-high graft attrition rate).

The donor area was shaved using a guard-less electric hair clipper. A local anesthetic (lidocaine 2% and epinephrine 1:1,000,000) was injected into the scalp donor areas without achieving tumescent turgor.

Skin-Responsive Follicular Unit Excision device—Dr. UGraft Device

The SRFD dashboard¹¹ is adjustable to skin thickness or firmness and has presets for 3 skin categories (Figure 1). Each of the 3 presets was calibrated to a set of torque settings, punch rotational speeds, and compound movement settings for 3 different punch movement types of varying durations (250–1,000 ms/score), which included a combination of continuous clockwise angular rotation, wide amplitude oscillation, and low amplitude oscillations (Figure 2A).

The movement types were preset according to the skin type, as follows: (1) thick, firm skin: first movement, continuous rotation; second and third movements, wide oscillation; (2) medium-thick firm skin: first movement, continuous rotation; the second movement, wide amplitude oscillation; the third movement, low amplitude oscillation; and (3) soft, thin skin: first movement, medium oscillation; the second movement, wide oscillation; third movement, low amplitude oscillation.

Torque (UForce on the dashboard) is the rotational force of the punch and ranges from 1 to 15 on the dashboard (Figure 1). It influences the penetrating power of the punch and is adjusted according to skin thickness and firmness. The UForce required to penetrate the skin sufficiently to release the graft was proportional to the degree of skin thickness and firmness.

The angular rotational speed of the punch—in revolutions per minute (RPM)—influences the punch speed and skin penetration depth in proportion to the speed.

The SRFD punch (Figure 2B) refers to a flared punch that is blunt at the graft-facing portions and on the inside but sharp at the outer edges facing away from the graft. Uniquely, the SRFD punch—The Intelligent Punch (Dr. U Devices Inc, Manhattan Beach, CA)^11–13—features proprietary texturing designed to exert a graft-pulling effect in the absence of vacuum suction equipment, self-propel into the skin, and navigate the curved subterranean course of the hair follicle with minimal assistance from the operator—minimal assist navigation (MAN)^11–13 (see Supplemental Digital Content 1, Video, http://links.lww.com/DSS/B298, demonstrating SFRD technique).

The curvilinear profile of the SRFD punch also benefits wound healing because it creates less-everted wounds relative to its conventional counterpart, which causes epidermal gap closure ahead of the deeper dermal portions. This leaves a smaller epidermal gap, requiring less scar tissue formation to close^11–13 (Figure 3A–C, and Supplemental Digital Content 1, Video, http://links.lww.com/DSS/B299, demonstrating the wounding and healing mechanisms of conventional vs an SRFD punch). The device has 3 punch sizes, namely, 20 gauge (G), 19, and 18 G, based on the universal sizing of hypodermic needles. The operator selects the punch depending on the diameter of the follicular units (FUs). Because of the typically wider diameter of the FU in African-descended patients, the appropriate punches are almost always confined to 19 G and 18 G with good healing footprints (Figure 4A,B). The abovementioned attributes in the punch design resulted in the retrieval of robust grafts (Figure 4C).

Figure 3.

Wounding and healing mechanism in the setting of a flared curvilinear FUE punch compared with conventional punches: Compared with traditional punches that cut in a downward and inward direction, creating a cylindrical wound with an outwardly folded edge of the skin [A1–A2], the flared curvilinear punch of the all-purpose skin-responsive FUE device enters the superficial skin with an initial outwardly directed cut into the surrounding tissue to create a wound path that is inwardly folded [B1–B2] (A and B) compared with wounds created by traditional punches, which after wound contraction has completed, still leaves the everted top portion of the wound open that must close substantially by secondary healing for closure and resulting in a larger scar [A3], in the flared curvilinear tip of the all-purpose skin-responsive FUE device punch, most of the wound closes through contraction, including the top portion, bringing the edges closer together. This allows the top part of the wound to either close through primary healing or require a smaller degree of secondary healing, resulting in less scarring [B3] (C) Reprinted with permission from Clin Cosmet Investig Dermatol. 2021;14(1):1,657 to 1,674; Dove Press.

Figure 4.

Preoperative FUE donor classification: An African male with thick, firm skin, mild acne keloidalis nuchae in the nape area, and coily hair (FUE donor Class V) immediately after (A) and 1 year after FUE using the all-purpose skin-responsive FUE device (B), and close-up view of curly grafts (C). FUE, follicular unit excision.

Initially, the patient's scalp skin type is determined using the SFS classification criteria to select the skin type on the device (Figure 1).² Independently, a patient's unique donor characteristics may require individual setting customization. Often, the UForce needs to be tweaked up or down to adjust the penetrating power of the punch.

The recommended method is to engulf the hair exit point, hold the punch together with the handpiece between 60° and 90° to the skin along the long axis of the exiting hair, and let the scoring continue under the weight of the equipment with minimal control (see Supplemental Digital Content 1, Video, http://links.lww.com/DSS/B298, which demonstrates this procedure). This maneuver, the standard method of use in all patients regardless of ethnicity, skin, or hair characteristics, allows the device's MAN effect to manifest by enabling the punch to propel itself into the skin. With this approach, and upon attaining the correct settings for the targeted donor, the punch navigates the subterranean curly course of the follicle and slows down or stops at the proper depth. At that depth, the grafts are typically fully separated from all anchoring tissues, thus requiring less effort to pull them out using jeweler's forceps (see Supplemental Digital Content 1, Video, http://links.lww.com/DSS/B298, which demonstrates this procedure). Postoperative care was provided using standard FUE protocols.¹

Transection Rates

The transection rate (TR) was defined as the percentage of grafts horizontally cut and damaged during FUE. The authors noted the graft TR as a range to recognize that this rate varied from one portion of the scalp to another in the same individual.

Surgeon and Patient Feedback

The 7 surgeons who contributed patient data for this report were asked to rate patient feedback as “Very Happy,” “Satisfactory,” and “Unhappy.” Furthermore, they were asked to compare their TRs and willingness to perform FUE in African-descended patients using techniques predating the reported SRFD. Willingness to perform FUE was scored on a scale of 1 to 5 (1, not at all willing; 2, somewhat unwilling; 3, neutral; 4, somewhat willing; or 5, very willing).

Statistical Methods

Mean values were calculated with standard deviations to evaluate the differences in characteristics and outcomes. Univariate analyses determined significant differences in the maximum TR across FUE classes, skin and hair types, and sexes. For non-normally distributed variables, the results of t-tests and analyses of variance were confirmed using nonparametric tests. For consistent reporting, parametric test results were reported unless there was a discrepancy with nonparametric test results, in which case, the latter were reported. The Spearman correlation coefficients were determined to evaluate the significant differences in settings and maximum TRs across age groups. Cohen d was calculated to evaluate the effect of skin and hair type on the maximum TR. p values of <0.05 denoted statistical significance. SPSS (IBM Corp., Armonk, NY) was used for statistical analysis.

Results

Patient Characteristics

Sixty-four African-descended patients (mean age, 40.5 years) underwent FUE. Other demographic characteristics and the results of preoperative FUE donor area assessments are summarized in Table 1. No significant differences in patient age, sex, or heritage for FUE class types were observed.

TABLE 1.

Demographics and Preoperative Findings

Parameter	N	%
Total number	64	100
Sex
Male	45	70.3
Female	19	29.7
Ethnicity
African	30	46.9
African American	18	28.1
Afro-Caribbean	10	15.6
Afro-Colombian	6	9.4
FUE difficulty grade—SFS
Class I	7	10.9
Class II	17	26.6
Class III	1	1.6
Class IV	12	18.8
Class V	27	42.2

FUE, follicular unit excision; SFS, Sanusi FUE Scoring.

Skin-Responsive Follicular Unit Excision Device—Skin-Responsive Follicular Unit Excision Device Settings

Table 2 provides a summary of the settings used.

TABLE 2.

Mean Settings Stratified by FUE Class and Skin and Hair Typing per Criteria Described in the Sanusi FUE Score Scale (SFS Scale)¹³

Parameter (n)	UForce	RPM	1st Movement	2nd Movement	3rd Movement
			Duration (Revolution)	Duration (W. Os)	Duration (M. Os)
All	3.92	2,960	527	866	346
Class I (7)	1.86	3,107	486	929	244
Class II (17)	3.94	2,968	503	829	341
Class III (1)	NA	NA	NA	NA	NA
Class IV (12)	3.83	2,804	495	725	408
Class V (28)	4.46	2,986	564	932	348
Hard-firm skin (39)	4.31	2,936	549	877	367
Medium skin (24)	3.39	2,991	498	852	318
Soft skin (1)	2.50	2075	375	800	405
Coily hair (45)	4.23	2,961	544	905	339
Curly hair (17)	3.33	2,944	494	778	372
Straight-wavy hair (2)	2.00	3,075	425	800	280

FUE, follicular unit excision; M.Osc, medium oscillation; RPM, revolutions per minute; Rev, Revolution; SFS, Sanusi FUE Scoring; W.Osc, wide oscillation.

Torque (UForce) Effect

The mean UForce setting required was significantly lower in FUE Class I than in Class II (p = .004), Class IV (p = .007), or Class V (p < .001) patients.

When stratified by sex, the mean UForce settings were significantly higher for men (4.23 ± 2.37) than for women (3.13 ± 1.40) (p = .044). No significant differences were noted for skin type, hair type, or age.

Compound Movement Effect

The only significant correlation between class and movement duration was in Movement 2, with a significant difference between Classes I and IV (p = .050) and between Classes IV and V (p = .003). Movement Durations 1 and 3 were significantly longer in male than in female patients (p = .005 and p = .015, respectively). Patients with coily/kinky hair had a significantly longer mean duration of the second movement than curly haired patients (p = .004). Mean compound movement settings for men and women are as follows: Movements (1) 563.10 ± 178.43, (2) 890.48 ± 166.10, (3) 388.10 ± 172; and Movements (1) 460.53 ± 80.93 (2) 847.37 ± 206.47, (3) 274.74 ± 76.40. Movements 1 and 3 were significantly greater in men than women (p = .005 and p = .015).

Angular Rotational speed—Revolutions Per Minute Effect

No significant differences in the RPM settings for FUE classes, sex, age, skin, or hair type were observed.

Punch Size, TRs, and Influencing Factors

Punch sizes used and TRs are summarized in Table 3. The overall TR was 3.36% to 5.54%. Comparisons between groups were performed using the upper limit of the TR range. FUE Class V patients had significantly greater TRs than Class I (p = .003) and Class II (p = .011) patients, but not IV. However, no significant differences were noted among Classes I, II, and IV. Patients with thick-firm scalps had a higher TR (mean, 6.67%) than those with medium scalp (mean, 4.42%) thickness and firmness (p = .003). Similarly, patients with coily/kinky hair (mean, 6.41%) had a significantly greater TR than those with curly hair (mean, 4.50%; p = .038). Skin type was found to have a significantly large effect (Cohen d = 0.858), whereas hair type had a medium-to-large effect (Cohen d = 0.617) on TR. However, no significant correlation was observed between the TR and age or sex. Although there was an overall difference in the TRs (p = .004) when compared across the 7 surgeons, the mean maximum TR was consistently <8% (range, 0%–15%).

TABLE 3.

Breakdown of UGraft Intelligent Punch Size Usage per FUE Class, Skin Type, and Hair Type

	Total Number of Patients (n)	Transection Rate (%)	19 G Only (%)	18 G Only (%)	Combination of 19 and 18 G (%)
All	64	3.36–5.54	21 (32.8)	37 (57.8)	6 (9.4)
Class I	7	1.43–3.29	4 (57.1)	3 (42.9)	6 (9.4)
Class II	17	3.00–4.88	5 (23.5)	9 (52.9)	3 (17.6)
Class III	1	1.00–2.00	1 (100)	0	0
Class IV	12	3.00–4.39	6 (50)	6 (50)	0
Class V	28	4.61–7.25	5 (18.5)	19 (70.4)	3 (11.1)
Hard-firm skin	39	4.44–6.80	11 (28.2)	26 (66.7)	2 (5.1)
Medium skin	24	2.54–4.42	9 (37.5)	12 (50)	3 (12.5)
Soft, thin skin	1	0.50–1.00	2 (100)	0	0
Coily hair	45	4.16–6.18	12 (26.7%)	28 (62.2%)	5 (11.1%)
Curly hair	17	2.82–4.65	8 (47.1%)	9 (52.9%)	0
Straight-wavy hair	2	2.00–2.50	1 (50%)	1 (50%)	0

FUE, follicular unit excision.

All FUE practitioners in the present investigation used 18 G or 19 G punch sizes, with 18 G being the most common choice.

Patient Feedback

In 26 patients, it was too early to gauge satisfaction. At 6 months minimum follow-up, 34 of 38 patients (89%) were “very happy,” while 11% rated their result as “Satisfactory.” Examples of the patient results are shown in Figures 4A,B, 5A,B, 6A,B, and 7A–C.

Figure 5.

Skin-responsive FUE results: An African American male with frontal and crown hair loss due to androgenetic alopecia before (A) and 13 months after the implantation of 1,719 grafts harvested by FU excision using the all-purpose skin-responsive FUE device (B). FUE, follicular unit excision.

Figure 6.

Skin responsive FUE results: An Afro-Brazilian woman with traction temple hair loss from late-stage traction alopecia before (A) and 7 months after grafting 760 grafts harvested by FU excision using the all-purpose skin-responsive FUE device (B). FUE, follicular unit excision.

Figure 7.

Skin-responsive FUE results: An African male with hairline recession from androgenetic alopecia before (A), immediately after implantation of 800 grafts harvested by FU excision using the all-purpose skin-responsive FUE device (B), and results at 10 months after surgery (C). FUE, follicular unit excision.

Follicular Unit Excision Surgeon Feedback

The maximum TR noted before using the new FUE technique ranged from 6% to 80% across study providers. All but one reported a >50% reduction in the TR after switching to the SRFD. The willingness to perform FUE on African-descended patients changed from a mean value of 2.58 before to 4.83 after the use of SRFD.

Discussion

The authors report low TR using a new skin-responsive FUE device in African-descended patients with features that address challenges in previous techniques while optimizing hair transplantation outcomes. The finding of an overall mean highest TR of 6% and TR range of 0% to 15% favorably compares with previous FUE studies of non–African-descended ethnicities that reported a TR range of 0.4% to 32%.^14,15 To the best of the authors' knowledge, this is the first statistically significant study to evaluate TR in patients of African descent, thereby illustrating procedural success and improved outcomes in a population largely understudied compared with other ethnicities.¹⁶ Although the authors found a significant difference in the TR reported by the participating surgeons, likely a reflection of experience level, their maximum TR of <8% for all surgeons compares favorably with the previously mentioned FUE studies.^14,15

The findings suggest that FUE graft attrition rates are significantly influenced by skin and hair factors.^2,11 The success of the skin-responsive technique, demonstrated by maximum complete graft TRs of <10% across all FUE classes, highlights its ability to navigate the subterranean hair course and adaptability to varying skin thickness and firmness. This retrospective study also underscores the utility of the SFS and FUE classification systems for presurgical scoring to determine FUE difficulty.

The findings present a more comprehensive schema to address racial disparities in dermatologic care.² Previously, patients with Afro-textured hair were often considered poor candidates for FUE hair transplantation based on the hair type.^3–6 In addition, the findings underscore that FUE techniques must be developed to accommodate the diverse hair and skin types among patients of African descent.^2,5

This study also indicates that torque is a crucial setting contributing to FUE success using the skin-responsive technique. The torque required during procedures was significantly less for FUE Class I patients as compared with Classes II, IV, and V. Previous studies suggest that the increased compact stratum corneum and thicker dermal sheaths with better-aligned collagen fibers and more abundant ground substances in African-descended patients contribute to increased resistance to FUE punches.² Although increasing the punch rotation speed can overcome the obstacle of skin thickness and firmness, the findings suggest that it did not contribute to the procedure's success. It also suggests that practitioners using other devices in a broader context should not use high rotational speeds in patients of African heritage; the emphasis should be placed on torque forces while increasing the scoring duration. The authors found that significantly lower torque forces and shorter movement durations were optimal in women compared with men, consistent with other studies reporting that women have softer and thinner skin than men.¹⁷

Notably, the consistency of the observed outcomes makes it unnecessary to conduct test procedures before qualifying Afro-textured patients for FUE; thus, FUE can be performed in this group without untowardly increasing the punch size.

This study confirmed that skin type has a more significant effect on TR than hair type. Furthermore, the finding that the TR was significantly higher in Class V than in Classes I and II patients validates the SFS grading system, with skin type determining this distinction.

Limitations of this study include the small sample size and variations in procedural techniques and skin/hair typing assessments across different FUE practitioners. Future studies should aim to replicate these results using larger sample sizes and standardized procedures.

Conclusion

African-descended patients have suboptimal and inconsistent FUE outcomes with currently used devices and techniques, leading to high TRs and unpredictable performance. The authors report consistent success in all African-descent patients who underwent FUE with a new skin-responsive FUE technique, with a maximum TR of <10%. The findings also indicate that skin thickness and firmness largely influence graft attrition rates in this population. FUE devices that consider these parameters in their design are expected to result in consistently low TRs in patients undergoing FUE, including those of African descent.

Supplementary Material

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