FUE as the first surgical option for hair reconstruction on scalp and facial skin grafts - case report.

Post-combustion alopecia presents a complex medical challenge with implications spanning dermatological and psychiatric disorders. The use of hair transplantation has proven to be a significant improvement for this condition. However, the current management involves various techniques, each with advantages and disadvantages. Progressive skin expansions, surgical scar reduction, and skin grafts containing hair follicles yield unsatisfactory aesthetic outcomes and have limited applicability as a first-line treatment for fire victims. So far, follicular unit extraction (FUE) has proven to be one of the most versatile procedures in such cases, having the potential to restore a natural anatomical profile closely resembling the pre-traumatic appearance that led to the traumatic alopecia. Additionally, it contributes to the improvement of associated psychiatric comorbidities, facilitating proper social reintegration and enhancing overall quality of life. This report focuses on a case of post-combustion alopecia and severe facial distortion due to third-degree burns resulting in severe psychiatric comorbidities, which benefited from a proper social reintegration and improvement of the quality of life after three consecutive sessions of FUE for scalp and eyebrow hair.

Platelet-Rich Plasma: Advances and Controversies in Hair Restoration and Skin Rejuvenation.

BACKGROUND: Platelet-rich plasma (PRP) and its combined therapeutic modalities have catalyzed new possibilities in dermatology; however, limitations in evidence and lack of consensus remain among clinicians regarding optimal composition, protocol, technique, and application. OBJECTIVE: To provide an update and analysis of the evidence for PRP in hair restoration and skin rejuvenation through review of recent available data, highlighting controversies and expert insights to guide future studies, and stimulate discourse and innovations benefitting patients. METHODS: A structured review and expert analysis of PubMed publications before October 2023, with a focus on recent literature from January 2020 through October 2023. RESULTS AND CONCLUSION: Growing literature supports the utility and benefits of PRP and related autologous products for applications for skin and hair, with strongest evidence for androgenetic alopecia and skin rejuvenation. However, this is limited by lack of consensus regarding best practices and protocols. Randomized, controlled trials with uniform metrics comparing outcomes of various compositions of autologous blood products, preparation methods, dosimetry, and frequency of treatments are still required. This will allow the medical discourse to grow beyond the realm of expert opinion into consensus, standardization, and more wide spread adoption of best practices that will benefit patients.

Long-hair follicular unit excision enhances the cosmetic results of hairline restoration: A retrospective study in Chinese recipients.

BACKGROUND: Long-hair follicular unit excision (LHF) is gaining popularity, especially for hairline restoration, because it helps avoid hair removal in the donor area and provides better immediate postoperative results. AIMS: This study aimed to assess the postoperative clinical outcomes of LHF for hairline restoration. PATIENTS/METHODS: Data from 248 patients (223 women and 25 men) who underwent hairline restoration with LHF between September 2018 and June 2022 were analyzed, and they were followed up immediately and 9 months postoperatively. The complications and survival rate of long-hair grafts were assessed. Patient postoperative satisfaction was assessed using a 5-Point Likert Scale. The Generic Quality of Life Inventory-74 (GQOLI-74) assessed the quality of the postoperative life. RESULTS: The planned extraction density was set at 15-25 FU/cm2. The mean number of total extracted hair grafts, transection rate in the extraction area, and extraction time were 1970 ± 124 FU, 3.9 ± 0.2%, and 3.2 ± 0.8 h, respectively. The hairline implantation density was set at 50-70 FU/cm2. The mean number of total transplanted hair grafts was 2031 ± 371 FU; the implant time was 3.8 ± 1.9 h. No serious complications occurred within 7 days postoperatively. The mean graft survival rate was 93.1 ± 1.3% at 9 months postoperatively. All patients were satisfied with the immediate postoperative results, and most were satisfied with the 9-month outcomes (mean overall satisfaction score: 4.7). The scores of physical function, psychological function, social function and material life function after operation were higher than those before operation (p < 0.0001). CONCLUSIONS: Hairline restoration with LHF could enhance the cosmetic outcomes and be widely used in clinical practice.

A Novel Method of Intraoperative Calculation in Follicular Unit Transplantation: 'The Sequential Strip and FUE Method'.

Hair loss, in particular androgenetic alopecia, has troubled humans since the dawn of history. Treatment options for hair restoration have undergone massive transformation from punch grafting to follicular unit transplantation. Current surgical treatment options in hair restoration fall broadly under two categories, follicular unit transplantation most commonly known as strip method and follicular unit extraction (FUE). The strip method though widely used initially is not so common now due to its fair share of disadvantages ranging from linear donor scar, scar widening to strip overharvesting and wastage of grafts. Follicular unit excision (FUE) was introduced as an alternative method for extraction of grafts to combat the donor linear scar produced by strip method but the disadvantages of FUE include the number of grafts harvested in a single session, moth eaten appearance of donor area caused by over extraction of grafts and harvesting from outside the safe zone. Newer developments like extraction of axillary hair, body hair and pubic hair have been sought to overcome the limitations of number of grafts harvested in a single session of FUE. With more patients now affected by alopecia in their early 20s, there is an ever-increasing demand from the patients for the youthful hairline and hence the focus has shifted towards mega and giga sessions of hair transplantation which pose danger of over extraction of grafts leading to depletion of available donor sites. This article elaborates the combined sequential strip and FUE method along with an intraoperative calculation model to overcome the limitations of over extraction and wastage of grafts. (1) Combination of techniques Strip method with FUE. (2) An intraoperative calculation model that aids in limiting over extraction and wastage of grafts. (3) It is a real time model which can be applied in practice with ease.Level of Evidence IV This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Paradigm Shift from Linear Strip to Follicular Unit Excision in Hair Restoration Surgery.

Follicular unit excision (FUE) is a very effective and valuable modality for obtaining donor hair follicles using manual, motorized, or robotic devices to harvest individual donor follicular units in situ without a linear donor scar or visible scarring making it ideal for patients who wish to wear their hair short and hide signs of surgery. Over the past two decades, FUE has become increasingly popular, and the rising demand for FUE has driven the worldwide market size of hair restoration surgery (HRS) to an unprecedented height.FUE has revolutionized the HRS industry and offers excellent cosmesis and high patient satisfaction. Unfortunately, a large part of the favorable appeal of FUE is due to false claims that it is "minimally invasive," "scarless," or "not even surgery." Most patients opt-in for FUE due to these misconceptions, which are advertised by "black-market" clinics offering low-cost FUE surgery performed by amateur, nonprofessional technicians on unsuspected patients. The technique appears deceptively simple, and many neophyte surgeons falsely believe that the learning curve of FUE is short because the barrier of entry is low and no previous surgical skill is required. Nevertheless, injuries on grafts are extremely easy to occur since FUE is a blind technique and can be minimized only with excellent technique, which takes years to master.FUE actually presents unique challenges for the surgeon and carries potential long-term permanent side effects if not performed properly. The surgeon must have a thorough understanding of the nuances of the FUE surgical technique to ensure consistent graft quality and favorable cosmesis of both donor and recipient areas. Efficient FUE requires dexterity, training, dedication, devotion, enthusiasm, cognitive clarity, scientific knowledge, experience, and an extended learning curve.FUE is an invaluable addition to the armamentarium of a hair restoration surgeon but has to be judiciously performed.

Concepts, Terminology, and Innovations in Follicular Unit Excision Hair Restoration Surgery.

Follicular unit excision (FUE) has emerged as the preferred method for hair transplants. Standardized terms and definitions established by members of the International Society of Hair Restoration Surgery and prominent hair restoration surgeons have become the standard, enabling effective knowledge sharing. This chapter provides an overview of the terminology relating to the field.The historical evolution of FUE and its pivotal role in modern hair transplantation is summarized. Anatomical terminology and graft-related definitions follow, providing insights into the scalp's complex structures and graft characteristics. The subsequent sections detail the terminology associated with graft excision and extraction, shedding light on the precise techniques and procedures employed. An exploration of various FUE techniques and the evolving landscape of FUE devices underscores the continual refinement of hair restoration practices. The chapter proceeds to discuss the "safe'" scalp donor zones, donor assessment terminology, and elements in identifying the optimal donor area for a successful FUE procedure. Additionally, punch dynamics and technique characteristics are examined, emphasizing their pivotal role in achieving superior FUE outcomes. The chapter concludes by discussing the classification of punches and graft evaluation terms, offering insights into the tools, and criteria used to assess graft quality and viability.

Follicular Unit Excision-Linear Ellipse Donor Harvesting Technique: Combining Standard Follicular Unit Excision with Follicular Unit Excision inside a Linear Strip (Modified Linear Strip Excision) to Optimize Graft Yield.

Follicular unit excision (FUE) graft dissection has become the dominant method of donor harvesting globally, however, only a percentage of donor hair can be excised inside the safe donor area before visible donor thinning occurs. Compared to linear strip excision (LSE) where all follicular units inside the harvested ellipse of hair are used, FUE poses substantial limitations for lifetime graft yield and, therefore, cosmetic coverage in patients with advanced pattern hair loss. This paper reviews how combining the donor harvesting methods of FUE and LSE has been shown to optimize graft yield while minimizing the risk of donor depletion from overharvesting. It then describes a surgical technique called FUE-Linear Ellipse (FUE-LE) where FUE dissection of grafts inside a demarcated linear ellipse eliminates the need for a large dissection team which has posed a barrier for many new practices that offer both the donor harvesting methods. For practices that currently offer only FUE, the addition of the LSE method by the modified FUE-LE technique is possible without specialized staff training or associated equipment costs. In this paper, surgery practices that have adopted this technique will report on their experiences. Hair restoration surgeons are encouraged to provide both methods of donor harvesting (FUE and LSE using FUE-LE) in order to optimize graft yield for patients and avoid long-term donor depletion. Based on limited experience, it appears the technique of FUE-LE will help achieve this goal.

Advancements in Graft Placement Techniques.

For decades, the placement of follicular units (FUs) into incisions in the recipient area was exclusively carried out using forceps. In 1992, Dr. Choi introduced an instrument known as the "implanter," which had the advantage of simultaneously creating incisions and placing FUs without damaging sensitive parts. Its initial popularity was greater in the East, primarily due to the characteristics of Asian hair. Asian hair is typically straight and thick, with FUs mostly consisting of just one or two hair.With the description of the follicular unit excision (FUE) technique in 2002 and its widespread adoption nearly a decade later, the advantages of using the implanter also gained popularity in the West. The uniformity in the size of FUs provided by the FUE technique and the possibility of delegating the placement were key attractions in the use of this placement tool. In addition to the traditional Korean implanter with a sharp needle, other implanters and inserters have been described.The choice of implantation technique depends on individual adaptation and the advantages and disadvantages offered by each instrument. Although forceps allow for safe placement in the hands of well-trained teams, the increased fragility of FUs obtained with the FUE technique has led to the growing acceptance of techniques that employ implanters and inserters.

Utility of Follicular Unit Excision Using Nonscalp Donor Hair.

Nonscalp donor hair harvesting or body hair transplantation offers patients an additional source of donor hair in cases when the scalp does not have an adequate supply for the intended recipient area. The most common applications for nonscalp donor hair are for patients with advanced hair loss or to camouflage scarring from prior hair restoration procedures. For patients with available body hair, the beard is probably the best source followed by the chest and abdomen. Combined, these sources may be able to provide thousands of additional grafts for transplantation. Nonscalp hair donor harvesting is technically challenging and should be performed by those with extensive experience in follicular unit excision surgical techniques.

Patient Selection for Follicular Unit Extraction versus Linear Strip Donor Harvesting.

Follicular unit grafts can be harvested using two methods: strip follicular unit transplantation and follicular unit excision. Each method can generate outstanding results, but both are uniquely different with respect to the advantages and disadvantages they offer. Devising a sound surgical plan is instrumental to assure that a patient's short-term and long-term goals can be met, but creating the best plan possible for the graft harvest process is not straightforward. This paper will review the various advantages and disadvantages of each graft harvest method, along with their short-term and long-term ramifications, so as to provide insight into the process by which a sound surgical plan can be developed for any patient seeking surgical hair restoration.

Impact of Hair Transplantation on Quality of Life.

BACKGROUND: Alopecia is defined as partial or complete hair loss. The most common form is androgenetic alopecia, which occurs in both men and women. Despite the nonsurgical options available for treatment, the only permanent solution is hair transplantation. Hair loss has been shown to have significant psychological consequences associated with loss of self-confidence, poor self-image and difficulties in social functioning. We aim to examine the effect of hair transplantation on quality of life and psychosocial functioning. METHODS: Forty-eight patients with androgenetic alopecia were enrolled in this two-center prospective study and underwent hair transplantation by the Follicular Unit Extraction method. Different questionnaires were used to assess their quality of life and other psychosocial parameters before and after hair transplantation. RESULTS: According to SF-36 Physical and Mental Health Score patients showed significant improvement in life quality after hair transplantation. Diener's Life Satisfaction Scale (DASS-21) revealed increased life satisfaction after the procedure. Stress and anxiety DASS-21 subscales showed significantly reduced results; while, the DASS-21 depression scale and MSPSS were not significantly changed. CONCLUSION: Taken together, quality of life and psychosocial functioning increased after hair transplantation. Structured abstract is required. Please provide.I insert name of paragraphs within abstract as follows: background, methods, results, conclusion Level of Evidence II: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Determination of Scalp Vascular Topography by Laser Doppler Flowmetry and Comparison of Vascular Damage by Different Blades in Hair Transplantation.

BACKGROUND: Although necrosis is a rare complication in hair transplantation, it is extremely traumatic for both the patient and surgeon and also has potential medicolegal consequence. Studies have shown that ischemia in the recipient bed is related to tissue damage caused by the instruments used and the number of grafts per cm². OBJECTIVE: We aimed to measure the effects of different instruments on circulation by dividing the recipient area of hair grafts of the same person into 2 sides as right and left. METHODS AND MATERIALS: Sapphire percutaneous blade was used on the right side, and a handmade razor slit was used on the left side in 12 male patients with consent. Subsequently, vascularity was evaluated with laser Doppler flowmetry. RESULTS: Scalp vascularity has so far only been evaluated with macroanatomic studies in the literature. First, the authors evaluated the effect of local anesthesia and adrenaline-containing swelling fluids on vascularity with a Laser Doppler Flowmeter. Afterward, the tissue damage caused by sapphire percutaneous blades and handmade blades (obtained from razor blades) were quantitatively analyzed and compared with each other. CONCLUSIONS: Our results showed that handmade razor blades caused significantly less tissue damage.

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

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 extraction megasession treatment of high-grade androgenetic alopecia in Asians: Introducing novel principles for surgical design.

BACKGROUND: Male androgenetic alopecia (MAGA) has been one of the most common reasons for hair consultation, which affects more than half of men under the age of 50. Recently, follicular unit extraction (FUE) megasession has been an attractive treatment option for patients with severe AGA. However, compared with hair transplant surgery by traditional FUE or follicular unit transplantation (FUT), a megasession lacks a suitable surgical design solution for Asian high-grade AGA patients. Therefore, we introduced novel principles for surgical design into FUE megasession for Asians. OBJECTIVE: The goal was to investigate the naturalness of hair, patient and doctor satisfaction level, and safety assessment of FUE megasession with the specific surgical design, to explore a novel technique for an efficient, satisfactory, and safe FUE megasession procedure. METHODS: Thirty-six Asian male patients with AGA in Hamilton Grade V-VI were enrolled in the research. All participants underwent FUE megasession treatment with the specific surgical design. The investigators observed the patients' general conditions, surgical information, naturalness of hair, and patient and doctor satisfaction level and adverse reactions. RESULTS: Before surgery, the average age of patients was 36.8 ± 9.6 years, and average duration of disease was 8.3 ± 3.8 years. During surgery, we harvested an average of 3705 ± 383 grafts. Recipient density ranged from 30 FUs/cm2 to 50 FUs/cm2 , and the total operation time was 10.6 ± 0.9 h. After surgery, patient-rated Likert score for naturalness of hair was as high as 4.72, and the doctor rated 4.61. Patient satisfaction score was up to 4.64, and the doctor scored 4.75. No serious side effects occurred in the study. CONCLUSION: FUE megasession with the introduced surgical design is a satisfactory treatment option for patients with high-grade AGA in Asians, with few side effects. The application of the novel design method can effectively lead to relatively natural density and appearance in one operation. Due to its remarkable effect, high satisfaction level, and few postoperative complications, FUE megasession with the introduced surgical design has great potential for Asian high-grade AGA patients.

Efluvio en línea de aparición inmediata asociado a trasplante capilar de alta densidad: descripción de 28 casos / Immediate-Onset Linear Effluvium Associated With High-Density Hair Transplantation: A Series of 28 Cases

Describimos 28 pacientes que desarrollaron una forma de efluvio postrasplante capilar con características no descritas en la literatura: a) morfología lineal; b) aparición inmediata (1-3 días); c) asociación con ‘dense packing’ en entradas (‘signo de Mickey Mouse’); d) progresión del diámetro de la línea (patrón ‘wave-like’); e) posible adición posterior de efluvio lineal concéntrico a vértex (‘signo del Donut’), y f) además de otros efluvios tampoco publicados por su inmediatez de aparición. La morfología lineal podría ser el resultado de la alta densidad colocada en nuestros pacientes, provocando hipoxia perilesional y efluvio de las unidades foliculares miniaturizadas que rodean la zona receptora. Debido a que la línea alopécica provoca inseguridad a los pacientes sobre una posible no colocación de injertos, recomendamos iconografía postoperatoria inmediata demostrando unión de áreas trasplantada y no trasplantada, así como la explicación previa al paciente de este fenómeno transitorio y completamente reversible en 3 meses (AU)

We describe 28 patients who experienced effluvium with previously unreported features shortly after hair transplant surgery. Notable features were as follows: a) a linear morphology; b) immediate onset (1-3 days); c) association with dense-pack grafting in areas of receding hairline at the temples (Mickey Mouse pattern); d) a progressive increase in the diameter of the hair loss line (wave-like pattern); e) in some cases, subsequent concentric linear effluvium on the crown (donut pattern); and f) other forms of previously unreported immediate-onset effluvium. The linear morphology could be the result of dense packing, which can cause perilesional hypoxia and loss of miniaturized hairs around the recipient area. Since linear hair loss can cause patient concern about graft failure, we recommend taking images of transplanted and nontransplanted areas immediately after surgery and warning patients in advance about these transient effects, which are fully reversed in 3 months (AU)

[Translated article] Immediate-Onset Linear Effluvium Associated With High-Density Hair Transplantation: A Series of 28 Case / Efluvio en línea de aparición inmediata asociado a trasplante capilar de alta densidad: descripción de 28 casos

We describe 28 patients who experienced effluvium with previously unreported features shortly after hair transplant surgery. Notable features were as follows: a) a linear morphology; b) immediate onset (1-3 days); c) association with dense-pack grafting in areas of receding hairline at the temples (Mickey Mouse pattern); d) a progressive increase in the diameter of the hair loss line (wave-like pattern); e) in some cases, subsequent concentric linear effluvium on the crown (donut pattern); and f) other forms of previously unreported immediate-onset effluvium. The linear morphology could be the result of dense packing, which can cause perilesional hypoxia and loss of miniaturized hairs around the recipient area. Since linear hair loss can cause patient concern about graft failure, we recommend taking images of transplanted and nontransplanted areas immediately after surgery and warning patients in advance about these transient effects, which are fully reversed in 3 months (AU)

Describimos 28 pacientes que desarrollaron una forma de efluvio postrasplante capilar con características no descritas en la literatura: a) morfología lineal; b) aparición inmediata (1-3 días); c) asociación con ‘dense packing’ en entradas (‘signo de Mickey Mouse’); d) progresión del diámetro de la línea (patrón ‘wave-like’); e) posible adición posterior de efluvio lineal concéntrico a vértex (‘signo del Donut’), y f) además de otros efluvios tampoco publicados por su inmediatez de aparición. La morfología lineal podría ser el resultado de la alta densidad colocada en nuestros pacientes, provocando hipoxia perilesional y efluvio de las unidades foliculares miniaturizadas que rodean la zona receptora. Debido a que la línea alopécica provoca inseguridad a los pacientes sobre una posible no colocación de injertos, recomendamos iconografía postoperatoria inmediata demostrando unión de áreas trasplantada y no trasplantada, así como la explicación previa al paciente de este fenómeno transitorio y completamente reversible en 3 meses (AU)

Immediate-Onset Linear Effluvium Associated With High-Density Hair Transplantation: A Series of 28 Cases. / Efluvio en línea de aparición inmediata asociado a trasplante capilar de alta densidad: descripción de 28 casos.

We describe 28 patients who experienced effluvium with previously unreported features shortly after hair transplant surgery. Notable features were as follows: a) a linear morphology; b) immediate onset (1-3 days); c) association with dense-pack grafting in areas of receding hairline at the temples (Mickey Mouse pattern); d) a progressive increase in the diameter of the hair loss line (wave-like pattern); e) in some cases, subsequent concentric linear effluvium on the crown (donut pattern); and f) other forms of previously unreported immediate-onset effluvium. The linear morphology could be the result of dense packing, which can cause perilesional hypoxia and loss of miniaturized hairs around the recipient area. Since linear hair loss can cause patient concern about graft failure, we recommend taking images of transplanted and nontransplanted areas immediately after surgery and warning patients in advance about these transient effects, which are fully reversed in 3 months.

Hairline Correction by Hair Transplantation for Reducing Apparent Face Length in Long-Face Women.

BACKGROUND: The long-face morphology is associated with aesthetic concerns, and surgery is often necessary to correct excess length in the frontal plane, in the upper, middle, and lower thirds of the face. However, correcting midline facial length in the frontal plane alone does not provide facial harmony. This study introduces a novel approach to correcting long-face morphology using measurements in the frontal, oblique, and lateral views, and reducing hairline measurements using hair transplants. METHODS: Eighty-three patients were enrolled in the study. The authors measured the midline facial length in the frontal plane and the lengths of the upper, middle, and lower thirds of the face. The authors also measured four additional distances in the oblique and lateral views, including the distance from the infratemporal hairline to the chin and from the sideburn to the chin. The patients' midfrontal hairlines were lowered, and the distances from the infratemporal hairline to the chin and from the sideburn to the chin were also shortened. The results were evaluated by patients and the surgeon using a five-point Likert scale. RESULTS: The mean patient Likert score was 4.5 (range, 3 to 5), and the mean surgeon Likert score was 4.9 (range, 3 to 5). No patients experienced adverse events. Three patients required touch-up surgery at the recipient sites to increase the hair density. CONCLUSION: This novel approach to correcting long-face morphology using hair transplants to decrease hairline measurements provided excellent facial harmony and symmetry. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Depth control in follicular unit excision: A new classification from a detailed analysis of 30 patients undergoing FUE technique for hair restoration.

BACKGROUND: In follicular unit excision (FUE), the concept of depth control (DC) has been created to minimize the risk of hair follicle damage. AIM: To analyze DC variation in different parts of the safe donor area of scalp; to propose Boaventura's new DC classification for hair restoration surgery using the FUE technique. PATIENTS/METHODS: Thirty male patients underwent hair restoration surgery. The donor area was distributed into 14 zones, with the minimum depth required for at least three atraumatic extractions of the grafts. When the extraction was not successful, 0.5 mm was added until reaching three follicular units, determining the DC area. RESULTS: Approximately 2000 extractions were performed on each patient to determine DC. For some areas, greater depth (2.54 ± 0.10 mm) was necessary. Fifty-eight percent of follicular units were extracted with 2.0 mm DC, and 3.8% required 3.5 mm DC. Thus, according to Boaventura's new classification for DC, grade I ≥ 2.00 mm, grade II from 2.1 to 3 mm, and grade III > 3.0 mm. CONCLUSION: There is variability in the DC of follicular units within the different areas of the safe donor zone. Moreover, we have proposed a new DC classification, which would represent a valuable estimation of surgery demand.