30 Oct

HAIR ORIENTATION IN HAIR TRANSPLANTATION 

   

» HAIR ORIENTATION PERSISTS

 
There is little debate today regarding natural hair groupings, but debate on hair orientation persists.  Some individuals have become proponents of the so-called  lateral slit technique and have adopted it.  We do not adhere to this dogma, but we recognize its potential benefits over the vertical or parasagittal slit.  We prefer to mimic nature’s natural angles.  These natural angles observed in a typical patient are depicted below.
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The photograph above depicts the natural alignment of hair growth.  The white arrows depict the native direction and angle of growth.  The heavier white markers depict a line 90º to the angle of growth.  The red bar represents a line in the lateral or coronal plane; this is the plane Dr. Hasson alleges to prefer because he feels it allows him to create greater apparent density and a fuller look.  We have found no evidence to support this claim, and we are able to achieve equal density and fullness using a hybrid technique. Furthermore, we find that our technique  replicates the aforementioned natural growth patterns.. On the other hand, following a completely lateral pattern of incisions will result in a relatively  unnatural pattern of hair growth. 

The lateral incision, as such, was first adopted by Dr. Wong, but has been popularized by his associate, Dr. Hasson.  The assistants for Dr. Limmer and Dr. Seager often use lateral incisions in their dense packing sessions (some say it helps them achieve better density and experience less popping).  Again, I have not found that a more lateral approach allows us to produce better density or greater ease of placement, but I am open to these arguments.  The lateral incision is of significant importance  to the field of hair restoration surgery because it directs physicians to better understand the natural geometry of hair growth.  This understanding may make it easier to achieve the appearance of fullness;  some initial, though not scientifically conclusive, studies suggest that the lateral incision does create better “fullness” than the vertical incision.  It may be that a slight change in the lateral incision of 10 to 20 degrees will result in even better density and the illusion of greater fullness in accordance with nature’s original intent.  Regardless, we prefer a maximally natural result and therefore attempt to mimic nature’s angles as much as possible. 

One can see that the direction of hair growth enables coverage of the area immediately in front of it and to its side.  The hairs on the top right side of the scalp are directed toward the left side of the scalp; likewise, the hairs on the top left side of the scalp are directed toward the right side of the scalp.  The hairs on the left lateral side of the scalp area are directed toward the left lateral side of the scalp.  The hairs on the right lateral side of the scalp area directed toward the right lateral side of the scalp.  Generally, remnants of two geometric spirals (some inaccurately call them whirls or whorls) are located in the temporal areas of the scalp.  One is located on the left and the other is located on the right temple.  These spirals may or may not be present and usually, when present,  are not entirely intact..  Sometimes a frontal spiral is noted in the center of the hair line. 

Many individuals have hairs that are angled toward the ear rather than toward the nose along one side of the frontal hair line.  This has been termed a cowlick in the past by some doting mothers or hair stylists.  If a central or paracentral spiral is present, the person will exhibit the aforementioned phenomenon.  As previously stated, this usually affects only one side of the scalp.   It is must less common to see it along both sides of the hairline, but this variant does occur.  The double cowlick results from two spirals moving in opposite directions (one clockwise and the other counterclockwise).

It is important to note that spirals are either dominant or recessive in nature, and that they manifest as  either full or partial..  A dominant spiral is fully visible, and has a defined  point of origin.  It has the capacity to obliterate the recessive spiral’s pattern as the two approach.  The dominant spiral advances unimpaired through the interface of the two spirals.  The dominate spiral turns in the opposite direction to its opposing recessive spiral.   One moves in a clockwise fashion, while the other moves in a counterclockwise fashion.  A recessive whorl takes a backseat to the dominant whorl and may or may not be fully visible.  Its center is typically found more laterally on the scalp and usually is not visible.  In other words, its point of origin is not seen; therefore, you will find distal elements of its geometric spiral and can only speculate as to its point of origin. 

.The back, crown or vertex region all refer to the same area on the scalp.  This area always has a dominant spiral.  Most commonly this spiral is located lateral to the midline on the right side of the scalp.    This dominant spiral typically is clockwise in orientation and its coverage extends anteriorly with hair directed from the left to the right side of the scalp.  The dominant spiral affects hair growth angles along the medial aspect of the contralateral (opposite) side of the frontal part of the scalp and all the hair growth angles up to the frontal hair line on its ipsilateral (same) side of the frontal scalp.  Usually there is also a recessive spiral on every crown. It typically is located lower than or inferior to the dominant spiral on the contralateral aspect of the crown or the opposite side.  Usually this spiral does not have a point of origin that is visible and its hidden origin is more lateral, as well as more inferior to the dominant spiral.  This recessive spiral usually moves in a counter-clockwise rotation.  This recessive spiral has elements along the lateral aspect of the top of the scalp and affects hair growth angles along the left side of the scalp. It typically affects hair growth angles along the lateral margin of one side of the posterior donor region (usually the left side).  It does affect hair growth angles across the midline.  Occasionally, a recessive spiral is not seen and the dominant spiral will hold sway across the entire posterior aspect of the donor region.  These individuals present the most difficultly with FIT, especially when it occurs in the Negroid patient.  Hair direction along the frontal hair line may result from the dominant spiral, but more commonly its direction arises from one of the three possible spirals that form in the temple or the mid-frontal hair line region.

One should note that hairs do not direct themselves naturally in an anterior or posterior direction.  Rather they are directed in such a way as to maximize coverage all over the scalp. They also tend to augment one another as much as possible so that the coverage value of each hair is maximized.  In other words they tend to “shingle” over one another in opposing directions so that the center of the scalp receives the greatest degree of coverage.  The directions of hair growth in nature typically produce the highest degree of coverage regardless of whether one parts the hair in the middle, the left side, or the right side. 

Victor Hasson claims that all hairs are directed in a line perpendicular to our coronally depicted red line. This simply is not so and in our opinion will result in less shingling and poorer coverage than following nature’s own angles of hair growth.  .A person might have a full appearance when looked at head on, but they would have a less full look when observed from the side.  More importantly, they will have a less natural result than if one followed nature’s pattern.

 It is very important to understand that Nature is efficient..  Typically, we find in our experience that following Nature’s rationale results in a fuller, more natural cosmetic effect. 

 It is our belief that recipient site incisions should be perpendicular to the large white lines so that the hair grows along the natural hair growth angles which are depicted by the small white arrows.  This will result in the best degree of coverage and the most natural direction of hair growth.

Hair Angles in the Vertex

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Here one can see the complexity associated with the vertex. There exist three possible spirals; a dominant spiral and two recessive spirals. The recessive spiral on the left side of the patient is directed counterclockwise although a clock wise spiral is also depicted on the left side. This is not an accurate drawing, however. This spiral is actually directed the opposite direction and gives rise the hair along the side of the head and the left side of the donor region. A third recessive spiral may give rise to the hair orientation in the back of the scalp toward the midline. It simply is something we must begin to study much more closely.

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Growth along the sides of the scalp

Growth along the sides of the scalp flows along similar spirals. The right side of the scalp flows in a clockwise direction, while the hairs along the left side of the scalp are aligned in a counter clockwise fashion.
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As you can see from the above photograph the hairs follow a spiral orientation whose source definitely includes the spiral on the left side of the vertex. It may include components whose origin is another recessive spiral located more laterally and anteriorly on the scalp. The tightness of the spiral columns as you move more anteriorly suggests this may be true. Also there is a rather abrupt change in the orientation of the hair to a tighter curve. There is often a third, more anterior spiral, which is located in the temple region. This spiral is lost generally at puberty in most males. It tends to remain much longer in females. It is also seen in some males of various ancestries such as in descendants of the Mayan Indians.
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Here you can see the direction of hair growth in the back of the scalp is derived from four different spirals. The dominant spiral in the vertex controls the majority of hair growth direction in the back of the scalp. As you can see the flow is predominately in a clockwise fashion in the vertex with the hair angled in an opposite direction to the flow of hair on the left side. The dominant spiral is depicted as it characteristically controls the flow of hair across the midline. As previously stated, the hair on the left side of the scalp is derived from a recessive spiral and controls hair growth direction along the lateral side of the posterior scalp over the mastoid region. I have seen unusual patterns where the dominant spiral controlled hair growth direction along the entire posterior aspect of the scalp. I find this the one of the most difficult patterns of hair growth to extract using FIT, but it is not impossible. Hair is directed along a three dimensional plane on both sides (along the left side it is directed in a positive X, positive Y, and negative Z axis, while on the right side it is directed along a negative X, positive Y, and negative Z axis). The neck region is comprised of two different spiral formations. These are either unique spirals or continuations of the dominant and recessive spirals that compose the more superior regions of the posterior scalp. Sometimes the neck spirals act in a more dominant fashion and alter the geometry of the posterior and inferior scalp by causing the hair to move along a different axis, angling superiorly or along a positive Z axis. This becomes the most challenging form of hair growth for the FIT procedure, when the angles are quite acute and the patient is an African American.
 
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This also shows the major problem associated with strip harvesting other than its greater degree of tightness, its invasiveness, its greater potential for pain, and it’s obvious production of a linear scar. The strip harvest destroys the natural geometry of the scalp. You can see how the spiral numbers are depicted on these pre-operative and post-operative photographs. Strip harvesting eliminates the ability to line up these spirals properly following strip harvesting. The spirals are shifted and it is impossible to repair this distortion of the natural geometry of the scalp after a single strip harvest is performed. In other words, strip harvesting permanently deforms the natural geometry of hair growth.

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This distortion of the geometry is depicted above following an actual strip harvest. The angles of hair growth are parallel to the blue hypodermic needles. In this instance, the donor region was temporarily stapled closed and the needles were inserted parallel to the direction of hair growth. You can see how the needles are angled along completely different sections of the geometric spiral so that they exit in completely different directions. It will be impossible to repair this geometric distortion.
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Here you see a three dimensional depiction representing how hairs are aligned in rows of spirals.
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This represents the triangular matrix of the follicular groups at an even smaller level. The follicular groups are aligned in rows, but they are located in offset spaces. These offset or staggered rows add to the illusion of fullness and coverage with the fewest hairs possible to achieve this illusion of fullness. The overall geometric patterns of hair growth are an amazing architectural achievement which begins at the smallest level, the single follicular group and is arranged in ever more complex geometric fractals or patterns that are all important to the appearance and degree of coverage possible. We firmly believe that it is imperative to adhere to these natural patterns as much as possible so that the most natural and fullest illusion of coverage is achieved. This is why we are strong proponents of making slits in the fashion of nature rather than in a purely coronal fashion, and it is also why we are no longer aggressive proponents of strip harvesting. Put simply, there are better options available.
 
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