Follicular Unit Grafts vs Small Mini Grafts
by: Dr. Ronald Shapiro
All forms of hair restoration surgery involve redistribution of existing hair follicles. No form of surgery will provide more hair follicles than those that currently exist. Therefore the success of hair restoration surgery for any patient depends on optimizing the cosmetic redistribution of an inherently limited number of hairs. The goal has been to find techniques that allow us to achieve both naturalness and the appearance of density within the constraints of this limited amount of hair. In an effort to improve naturalness the trend has been to use smaller grafts and this has ultimately led to the "follicular unit" graft and total "follicular unit" grafting. Most experienced practitioners of hair restoration surgery agree that the hairline should be a "feathered" zone, with deliberate irregularities, created using several hundreds of these 1-2 hair follicular units. However, there continues to be active debate over the optimal method of hair transplantation in the central area behind the hairline. Some believe that density cannot be achieved using only 1-3 hair follicular units in this area. They feel that slightly larger 3-5 hair minigrafts "cut to size" need to be placed in this central area where they typically will not be scrutinized as closely for naturalness, but where they will contribute to an overall increased number of hairs to achieve the "illusion of density".
With respect to density, in many cases the size of the scalp area needing coverage is larger than the remaining donor area. Attempting to achieve "equivalent" density would rapidly outstrip the available donor follicles. However, achieving identical density is not necessary to obtain an excellent cosmetic result as the "illusion of density" can be achieved with far fewer follicles than existed pre-hair loss. The resulting cosmetic appearance is an optical illusion, the appearance of density rather than actual density.
With respect to naturalness, if the general appearance of the hair does not reveal an unusual pattern of individual hairs or groupings of hairs – under any circumstance (i.e. wind, rain, water sports etc) and at any level
of inspection, the appearance of naturalness has been achieved, and with fewer than "normal" numbers of hairs.
The challenge becomes how to redistribute this precious limited commodity with the least amount of waste and a high degree of follicle survival, while maintaining the most uniformly cosmetic results. The debate, in essence, centers on the comparative advantages and disadvantages of 1-3 hair "follicular units" vs. 3-5 hair minigrafts "cut to size, " with respect to achieving naturalness and density in the central area behind the hairline.
"Follicular units" are prepared by isolating naturally occurring groupings of 1-3 hairs and trimming them of as much epithelium and extra tissue as safely possible. The minimal amount of epithelium left on these grafts limits the "pitting" that sometime occurs when grafts are unintentionally placed too deep. Because "follicular unit" grafts are smaller than untrimmed grafts with equivalent amounts of hair they can fit into small microincisions placed very close together. These natural groupings combined with their ability to be placed in close proximity to one another closely mimic nature, thereby creating the highest degree of ‘naturalness’ on a consistent basis. They can be undetectable under close examination.
The controversy over using only follicular units in the central area has to do with their ability to produce the" appearance of density". Density is a function of the number of hairs in an area, not the size of the graft. Above a certain threshold, the same amount of hair should produce the same appearance of density independent of the type of graft used. The problem with follicular units is not that density can’t be produced but that density is more difficult to produce. A number of factors make the successful use of follicular units more difficult.
First, due to their small size, follicular units are more fragile than larger grafts. Placing a large number of these very small grafts in closely approximated microincisions is technically difficult, increasing the risk of follicular injury and subsequent poor growth. However, with experience, skill, and proper placing techniques this problem can be overcome.
Waste is another problem that can occur when using "follicular units". Waste is distinctly different from follicular injury and poor growth. The term "waste" refers to hair follicles that are lost or discarded during the trimming process. A given area of donor tissue has a finite number of hair follicles. Hairs transected during the donor harvesting and dissection process have the potential of being discarded. Intrinsically, the extensive trimming necessary to produce good quality follicular units increases this risk of waste. Recent reports state the increased potential for waste associated with cutting follicular units can be nearly eliminated with skillful use of the stereoscopic dissecting microscope. The degree of waste is less with small minigrafts "cut to size" because these grafts use all of the donor tissue including the transected hairs. The yield and quality of the transected hairs found in small minigrafts has not been established
Finally, because there are less hairs per graft, it takes a larger number of "follicular units" to move the same amount of hair to an area as with larger grafts. This ultimately makes the procedure more labor intensive, time consuming and costly.
Density can be produced when using follicular units if the above problems are addressed. However it takes a lot more effort, time, and skill. The question is: Is the increased degree of naturalness achievable with "follicular units" clinically significant in the central area where grafts are less scrutinized? Is this degree of increased naturalness worth the risk and increased effort necessary to produce density with this type of graft?
SMALL MINIGRAFTS "CUT TO SIZE"
Small minigrafts " cut to size contain an average of 3-5 hairs per graft. The size of the graft is determined by the donor density. Grafts can be cut thin and flat for slits, or more rectangular for punches. It is my opinion that the most consistently natural 3-5 hair minigrafts are thin flat grafts for slits because the hairs line up linearly and there is less chance of compression. If done properly a thin, flat minigraft placed in appropriate sized slits can look like 2 follicular units lined up behind each. These minigrafts, when compared to "follicular units", are less susceptible to trauma and poor growth. Also, because not each follicular grouping is being separated, there are fewer cuts with the dissecting knife and the risk of transection and waste is inherently less. Finally, since the same numbers of hair can be transplanted with fewer grafts, this technique is less labor intensive, time consuming and costly.
The disadvantage of 3-5 hair minigrafts "cut to size" is the increased potential to be less natural and look "grafty". These grafts have an increased risk for compression, especially if the grafts are not cut thin and flat or are placed in too small a slit. This problem is more likely to occur in patients with high density where grafts cut to size may unintentionally contain more than 5 hairs. Because these grafts contain a small piece of epithelium, there is an increased chance of pitting. If this small piece of epithelium is pushed below the layer of stratum cornea and stays there, the body will try to incorporate or encyst it. The former will result in pitting; the latter in a permanent annoying bump possibly associated with inflammation and foreign body reaction. The most effective way to avoid pitting is to make the incision only as deep as necessary to incorporate the graft follicle up to, but not including the epithelium.
In conclusion, it is possible to achieve the appearance of naturalness and density on a consistent basis with natural follicular groupings called "follicular units". This method requires greater numbers of grafts and technical skill in order to achieve cosmetic density. But once the technical skill to perform this technique is achieved the look is invariably natural. The question is: Is the increased degree and consistency of naturalness produced with follicular units worth the effort and risk necessary to achieve the appearance of density, especially in the central area were grafts are less scrutinized.
Mini grafting in the central area using 3-5 hair grafts "cut to size" offers the practitioner and patient a faster, slightly more economical way to achieve coverage, and if performed skillfully can achieve nearly the same degree of naturalness as single follicular groupings. However, the caveats are several, and when not observed, the results are a step down from the Mercedes Benz of grafts, the follicular unit.
About the Author
Dr. Shapiro is widely recognized by his colleagues as a leading practitioner and teacher of the most advanced hair restoration procedure – follicular unit hair transplantation. He adopted this procedure early in the 1990s and helped popularize this advanced procedure. He was the first physician honored to demonstrate this surgery live before a wide audience of colleagues at the ISHRS annual meeting in 1995. http://www.hairtransplantnetwork.com/