FUE or follicular unit extraction, now called excision is one of the methods for hair follicle harvesting in hair transplantation.FUE involves harvesting of donor hair follicles from the safe donor area using a circular knife called ‘punch’. The scalp is commonly used as a donor area, but other donor areas like the beard, chest and other parts of the body can also be used. The procedure has achieved increasing popularity, as compared to the strip method of follicle harvesting commonly called FUT, as FUE avoids permanent long linear scar.
In 2017, a nomenclature committee of ISHRS concluded that the term follicular unit extraction is inappropriate and misleading because it is a histological term rather than an accurate anatomical and surgical term. The committee recommended “follicular unit excision” as it explains the two steps of the process: incision and extraction. The term also carries greater surgical implication, that this is the surgical domain.
Follicular Unit Excision is defined as the surgical technique that refers to circumferential incision of the skin around the follicular unit bundle or group of hair follicles to extract a full-thickness skin graft containing hair follicle(s), intradermal fat, dermis, and epidermis.
Basic surgical steps:
There are two surgical events and four technical steps in the FUE method of follicular unit extraction. Surgical events are-
First event-The scoring of the epidermis to get inside the deeper tissue.
The second event- The dissection of follicle means separating the follicle unit from surrounding dermal tissue.
The scoring of epidermis and dissection of follicles together are called ‘excision of follicles’.
Surgical events. A follicle with its attachments. B. scoring of the epidermis by the punch. C. Dissection of the follicle from its attachments.
The technical steps-The surgery is performed in 4 steps:
Step I- Alignment: Keeping the long axis of the punch axis along or parallel to the hair shaft.
Step II- Engagement: The cutting edge of the punch is fixed over the skin surface for scoring the epidermis. The punch is centered on the exit point of hair or the epidermal blush.
Step III- Advancement- using the rotational and or oscillatory and axial force the punch is advanced deeper in the epidermis to separate the follicle from all surrounding attachments, which is the dissection of the follicle unit.
Step IV- Extraction: The follicular unit is removed.
The precise depth of the insertion of punch is the key to harvesting an intact follicular unit. The follicle is firmly attached to the surrounding tissues called ‘tethering.’ The tethering is linked to the existence of various lateral connections between the dermal sheath, pilosebaceous elements, and connective tissue of the hypodermis. There is also a deep tethering between the hair follicle and the subcutaneous fat at the bottom of the follicle unit (neurovascular attachments).
One of the challenges in FUE donor harvesting is the variability in the viscoelastic properties of the FUE donor area. The patient-to-patient variations in the epidermis, dermal-epidermal junction, and subcutaneous tissue contribute to the challenges of donor harvesting and minimizing the complications.
Instruments For FUE
FUE instruments have two essential parts – a punch and a handle. There is a wide range of such instruments available. The handle could be manual or it may be motorized.
The punch is a circular knife to dissect the follicle or follicular unit. The diameter of the punch is variable which ranges from 0.7 to 1.2 mm. The good-quality punch should have a thin and strong wall with a smooth surface. The larger punch has less transaction rate but results in more scar and greater vascular compromise. Small diameter punches cause more root transection, will harvest thinner grafts bearing fewer follicles per FUs, but cause less donor scar. The punch size of less than 0.8 mm is called a small punch, between 0.8 mm to 1.0mm is medium and a punch bigger than 1.0 mm is labelled as a large punch. Most of the surgeons use 0.9 to 1.00 mm diameter punches for the scalp and 0.7 to 0.8 mm for harvesting body hair follicles.
Depending on the cutting edge of the punch, the punch can be sharp. The dull punch needs more pressure to cut as compared to the sharp punch. The cutting edge of the punch can be outside bevel, inside bevel, or middle level. There are different types of punch edges in different instruments. Overall, the objectives of a punch are to harvest the better quality of grafts with more perifollicular tissue, less transection, and with good speed of harvesting.
John Colehas been promoting sharp punches and he has simplified the biomechanics of extraction to support his theory. When force is applied over the skin, there is compression of the skin and follicle underneath. The dull punch needs more force to cut the skin, which leads to more distortion, thereby increasing the transection rate and risk of buried grafts. If the sharp punch is used, less force will be required to cut the skin, so there will be minimal distortion and better graft quality. He extended his concept further by reducing the contact surface of the punch to the skin to decrease the frictional injury to tissue and devised an ultra-sharp serrated punch. The potential problem with a sharp punch is increased transection rate, which is a matter of concern. It can be controlled by practice and depth precision.
The hybrid punch is flared at the end with a sharp outer edge and dull inner edge. The sharp outer edge is to score the epidermis, and the dull inner punch is to dissect the hair follicle. This design helps in reducing the transection of hair follicles.
The handle is a device over which the punch is mounted. This is used to create an axial, rotational, and/or oscillatory force to score the epidermis and finally dissect the follicle. The handles are either manual or motorized.
A good quality FUE handle is usually autoclavable, made of stainless steel. There are different varieties of handles, most commonly used are CIT manual punch handle and Versi handle.
The selection of sharp or dull punch is as per the choice of the surgeon. The size depends on the size of follicular units, donor site, and experience of the surgeon.
FUE Motorized technique instruments
To improve the speed of follicles harvesting the punch is mounted on a motorized handle. The motor is either electrically operated or battery-powered. The motor makes a revolution at a speed of 100 to 20,000 RPM. Initially, the revolutions were uni-directional, but in the advanced systems, the oscillatory movements were added. The punch is mounted over the motorized handle and placed around a follicle or follicle unit, the rapid spinning motion of the punch allows for fast scoring of skin and easy separation of the follicle.
During the initial phase of the motorized method of FUE, the graft yield was less due to the strain put on the follicular unit through rapid rotation, tension, heat, and friction. Later on, these problems are resolved by reducing the speed of rotation and the addition of oscillatory movement.
Basic Motorized system for FUE. A-basic console for control of the speed of motor. B- a motor and handle for holding the punch and foot paddle for control.
Harris developed the SAFE System which utilizes “blunt” instrumentation to dissect the follicular units with minimal risk of follicle transection. Harris introduced the dull Hex punch on a motor. The potential problem associated with dull punch was the increased incidence of buried grafts and slow speed of extraction in comparison to the sharp punch.
Trivellini Device Developed by Dr. Roberto Trivellini, the Mamba FUE Device is a multifunction programmable motor that incorporates in-line suction, full rotation, oscillation, and vibration . The device also uses a unique flat punch design called the “Edge-Out” punch. Most advanced FUE device.
Trivellini Mamba System used at Rejuvenate hair transplant centre.
Devroye System–Developed by Dr. Jean Devroye, this FUE battery-powered device uses an oscillating flat punch controlled by a very sensitive foot pedal. The device allows very short arc punch oscillation.
SUCTION ASSISTED MOTORIZED DEVICE / NEOGRAFT
This is a motorized device with a sharp punch and both negative and positive pressure mounted on a right-angled handpiece. The negative pressure sucks the graft after dissection; they are directly collected in a small chamber. The grafts can be implanted in premade slit by another device attached to the machine. The grafts once loaded in the implant using negative pressure and inserted in the slit by positive pneumatic pressure. The system did not gain popularity because of technical problems, and the grafts are collected in a dry chamber, making them prone to desiccation.
Image-guided Robotic device
Restoration Robotics developed a digital image-guided robotics system in 2011 that scores the FUs with an image-guided motorized punch The robotic system is composed of a computer, a mechanical arm, a punch mechanism, a video-imaging system, and a user interface. Its dissection technique is enabled by two punches that are concentrically arranged. The small diameter inner punch has sharp cutting capabilities to score the uppermost part of the skin, and the outer dull punch has a blunt edge that dissects the FUs from the surrounding tissue, minimizing injury to the grafts. The device can suggest the target unit; align the punch for precise scoring, and deeper dissection. The robotic system utilizes the Harris SAFE methodology. The sharp punch scores the skin, followed by a dull punch that penetrates the deeper tissue and dissects the follicles. The dissected follicle is removed manually. To stretch the skin surface, a skin tensioner is used.
The robot is an expensive device and uses multiple disposable materials, which increases the cost of the procedure as well. The use of robots will undoubtedly overcome human error, shorten the learning curve, and reduce the surgeon’s time. Still, it cannot bypass the surgeon, as evaluation of donor area, recipient area planning needs an experienced specialist.
Operation theatre setting:
One should perform hair transplantation in a well-equipped operation theatre setting. There should be a facility for general anesthesia as well as resuscitation equipment. The atmosphere of the theatre should be patient-friendly. There should be an operating table or chair as per the preference of the surgeon. One should consider that this surgery may require constant positioning of the patient as well as a surgeon for a long period of time. Therefore the position of the surgeon, as well as a patient, shall be very comfortable. Thai massage chair or modified dental chair, or surgical operating table with some modifications can be used for the comfort of the patient. A prone and lateral position with frequent change of position of the patient will facilitate cooperation from the patient. A simple DVD player can be used for patients’ entertainment. To avoid claustrophobia, a hole can be made on the head-end side of the operating table with a silicone ring. There should be good cold light. Surgery should be performed preferably using a 3.5 or 4.5X magnification loupe.
A B C
Thai massage chair. B modified dental chair. C Operating table with extra cushion, attached cushioned handle, and neck pillow
D E 40 F
D. Car DVD player hanging from the light.
E- horseshoe-shaped hole on the head end of the operation table.
F-operation room equipped with all emergency equipment including an automated defibrillator.
When FUE Is Done
There are a few conditions where FUE is the preferred choice over the strip method of hair transplant.
A person wishes to keep his hair short; the FUE is preferred as the FUT linear scar may show through the short hair.
There are cases in which the scalp laxity is less, and strip surgery might give a wide scar, also patients with a history of hypertrophic scar or keloid tendencies are a better candidate for FUE.
A patient having a low pain threshold and wanting to get back to his job earlier, the FUE is preferred as postoperative pain is comparatively more with FUT.
Cases who have already undergone strip surgery and the second strip is not possible, or they do not want the second strip, the FUE is a choice.
The FUE is the only method to harvest follicles from other than the scalp donor areas like the beard, chest, and other body parts.
The FUE is also done along with the strip method as a combination method of hair transplant.
The manual method of FUE
The punch is mounted on the handle, first epidermal scoring and then dissection of the follicular unit is performed by advancing deeper in the dermis. Manual harvesting can be performed using two steps or one-step techniques.
Two-step manual FUE technique
A sharp punch is mounted on a handle, aligned to the hair shaft, engaged at the exit point or epidermal blush, and epidermal scoring is performed using oscillating force. In the second step, the sharp punch is replaced with a dull punch. This punch is inserted through the same incision. Maintaining the same angle, the punch is advanced deeper by oscillating movement and axial force. Once the arrector pili muscle is cut, there is a feeling of giving way which is the endpoint of cutting. The punch is removed and the follicular unit is picked up using a forceps. The initial few follicles should be examined for transection, angulation, and depth of hair follicles for further punches.
Single-step manual FUE
The scoring of the epidermis and dissection of the follicle unit is performed using the same punch in one step. The depth is chosen depending upon the length of the hair follicle which is usually 3 to 4 mm. The CIT handle has depth control; otherwise, a guard can be used to control the depth of penetration of punch. The guard can be made by using an infant feeding tube or silicone tube. After completing the precise depth dissection, the punch is removed. The graft is harvested and examined for any injury, direction, and length.
Motorized FUE method
The punch is mounted on the motorized handle. One should hold the motor handle in a pen holding position, stabilize the grip, adjust the RPM of the motor, and target the follicle. The exit point of the follicle is targeted at the centre of the punch. The author advises centering the punch over epidermal blush. Epidermal blush is identifiable under magnification. Aligned the punch at the angle of the hair and the motor is started. With slow-motion, the punch is engaged in the epidermis, and scoring of the epidermis is done. After epidermal scoring, the punch is advanced deep with steady pressure to dissect the follicle to its full depth. The speed of the motor is adjusted during the procedure as per the feel of resistance of the tissue.
The depth of the punch is controlled by using a depth guard over the punch. The depth of punch is decided as per the length of the follicle. For this, the initial few follicles are examined after extraction, and length is measured.
A B C
Figure A to C-How to apply depth guard. A. The first few test graft are harvested, and the length of graft is assessed. B- Infant feeding tube or other silicone tube is taken C, the silicone tube guard is mounted over the punch, so the punch reaches just above the level of bulb of the hair follicle.
Figure D to J Steps of FUE.
D (Step I) alignment.
E- Centring the centre of the punch to epidermal blush.
F (Step II) engagement.
G. (Step III) Advancement
H Dissected follicle in its place.
I- (Step IV) removal or extraction of the dissected follicle.
J extracted FUs
Follicular graft may sustain various types of injuries during harvesting. It is crucial to examine the harvested grafts to identify various types of injuries and modify the procedure.
Transection – Term used to report any microscopically visible division of a follicle along its entire length. A graft is considered completely transected when all of the follicles are cut transversely. The partial transection is when some follicles are cut, leaving one or more intact follicles.
A Partial transection B.Complete transection
Capping or Topping – After incising a targeted graft a small-cap or top of tissue (epidermis and dermis) is harvested without the evidence of hair follicle, which remain in the donor site. In most cases, this is due to not having achieved sufficient depth with the punch before liberating the graft.
De Capping of the follicle.
Pluck – A pluck is naked follicles devoid of all or part of soft tissue components connective tissue sheath (CTS), outer root sheath (ORS), inner root sheath (IRS), and the dermal papilla (DP). In some instances, only the IRS may remain there.
Broken or Fractured Follicle(s) – The follicles are broken into two or more pieces. Such trauma typically results from an excessive force applied with forceps during the extraction of FUE.
fracture of the hair shaft in follicle
Safe excision density– How many follicles can be extracted?
One should consider donor area limitations and avoid excising from areas likely to be affected by androgenetic alopecia (AGA). This usually means excluding the nape of the neck, superior lateral fringes, and the superior aspect of the occiput near the region of the balding crown.
Most FUE experts recommend 10-15 grafts excision/cm² as a safe single pass density in a person with a baseline average density of 65-75 grafts/cm2. James Harris reported routine use of higher excision density in the range of 20-25 grafts/cm2 . In the case of a patient with an average baseline density of 70 grafts/cm2, an excision density of 10-15 grafts/cm2 leaves a residual FU donor density of 55-60 grafts/cm2. Further FUE harvesting with the same excision density would further reduce residual density to 40-45 grafts/cm2. Visible thinning may be expected when the residual density is between 40-50 grafts/cm2, especially in short hairstyles with straight and thin hair. The extraction shall be uniform, to avoid a ‘moth-eaten appearance’.
With more and more experience of FUE, sharp punches, and more sophisticated motorized devices, a large number of follicles can be harvested in one session. When grafts extracted are more than 2000 to 2500 grafts in one session, then it is called the mega session. When the grafts are more than 4000 grafts in one session, it is called a Giga session. From scalp donor area extraction of more than 3000 grafts in one session is not advisable. The author considers approximately 2500 grafts in one session from the scalp donor area is safe limit, of course, it depends on the donor density too.
When FUE Should Not Be Done
Contra indications for FUE surgery-
There are a few conditions where the FUE procedure is not a preferred procedure.
Patient with extensive scarring of the donor area.
patients having a high curl of hair where very high transection of follicles are expected.
The surgeon is not trained enough.
The patient is not willing for FUE.
The patient not willing for head shaving requiring FUE, otherwise unshaven FUE is the option.
Female patients where the shaving of the donor area is not preferred, the Strip method is the choice, or unshaven FUE is another option.