The following factors are arguably the most important components of hair transplant surgery:

• Coverage
• Density
• Angle Control
• Naturalness

Before analyzing these issues, I should address the issues of density vs. coverage.

In the initial assessment of any patient the physician will assess the final hairloss pattern and amount of hair in the permanent donor zone. Patients with less donor hair and greater degree of final hairloss will most likely need coverage more than density. Patients with relatively more donor hair and a lesser degree of final hairloss (ie: 2A – 4A) will usually desire greater density.
We would thus plan our surgical intervention with either coverage or density as our goal.

Until this point in time the problem has been that unless we achieved density the transplant looked pluggy. Follicular unit transplant for the most part addressed this issue by allowing us to achieve density with relative ease. However, follicular unit transplantation does not generally provide a good aesthetic result if the grafts are not densely packed. Here the hair-dense follicular units stand out against the background of bald scalp.

The lateral slit technique addresses both the issues of achieving greatest possible density and naturalness at relative low density.
To understand this concept one must first understand that all multi-haired FU’s have one plane in which they provide greatest coverage. In this plane the follicles are seen to be lying along side one another rather than on top of one another.

By creating recipient sites which maintain the FU graft in the plane where the follicles of the FU lie alongside one another we get improved coverage. In addition the grafts do not look pluggy as would be the case where the follicles lie on top of one another. We are thus able to achieve much greater naturalness even with lower density transplants.

We must thus make the skin incision at 90° to the direction of hair growth irrespective of the location on the scalp. In the frontal scalp the incisions would thus be in the coronal or lateral plane. In fact nature employs this exact setup.
Observe the graft orientation in the following photos of donor hair.

How does this technique allow transplanting at greater densities?

1. Maintaining a healthy blood circulation in the recipient area.
   This is done by limiting the depth of the incision in the recipient skin such that it does not affect the circulation of the skin. In the lateral slit technique the incision is shallower than with sagital incisions.
2. Reducing compression of grafts, which occurs when many grafts are transplanted at high density.
   In traditional sagital (front to back) incisions the pressure that the grafts exert on the site walls of the incision are all added together by the pressures produced by its neighboring grafts.
3. In the lateral slit technique the pressure is exerted in an up and down direction.
   In this plane there is free expansion into the area above the scalp, and the individual pressures executed by each graft do not affect the pressures executed by neighboring grafts.

Recipient sites are made as small as possible. This is done by measuring an individuals FU size and creating a recipient site with a custom cut blade, accurate in size to the nearest hundredth of a millimeter.

No other technique even comes close to the lateral slit technique in maintaining precise graft angulation. In our technique the graft is tightly sandwiched between the front and back walls of the incisions.

The photos below show the immediate post operative views of hair transplants using our technique. You can clearly see how the follicle angulation is precisely controlled.

There are several other advantages to this technique and its implementation which are however beyond the scope of this discussion.

In conclusion: I have used the sagital incision method on approximately 2000 cases up until 1996. Since that time I have done approximately 2000 cases using the lateral technique. In my mind these is no question of the superiority of the latter technique.

The technique was first performed by my associate Dr. Jerry Wong. I have simply refined it. In our combined experience of over thousands of cases using this technique we are unaware of any cased of poor transplant growth due to this technique. Additionally we are unaware of anyone who employs our technique together with follicular transplantation who has experienced poor graft growth.

Article courtesy of Doctor Victor Hasson of Hasson & Wong Hair Transplant Clinic