Vertex Transition Zone: Why It is Important and What Does it Mean
The vertex transition zone (VTZ), or vertex transition point, can also be thought of as the posterior “hairline” in that it forms the transition from the flat, horizontal midscalp and the vertical plane of the crown. As a reminder, the anterior hairline, or hairline, is formed at the intersection of the forehead and the horizontal plane of the scalp. One can think of these two as borders on a box in which the vertex transition constitutes the back border, as illustrated in the accompanying Figure.
Figure reprinted with permission from Hair Transplant 360, Volume 1 (Jaypee Brothers Medical Publishers, 2011), Samuel M. Lam MD
The vertex transition zone is often then the posterior limit of a hair transplant that serves to rebuild the hairline and the central midscalp. Similarly, it is oftentimes the anterior limit when a crown is rebuilt. It is rare that a surgeon will be able to rebuild a bald scalp from the front hairline all the way to include the crown in a single session because there is just not enough hair to make both areas in a single, initial pass look dense enough to be worth the effort and to be natural in appearance. Put in another way, scattering 5,000 hairs across from the anterior hairline all the way to include the bald crown the first time can look grafty and still keep the patient looking bald. Accordingly, the vertex transition zone serves as the juncture between session 1 and session 2 of two hair-transplant procedures with usually session 1 being allocated from the front hairline to the VTZ and session 2 from VTZ to bottom of the crown.
Besides serving as a transition zone between the front scalp to the crown, the VTZ serves another important aesthetic purpose. If you think of the front hairline as framing the face, the VTZ serves to frame the posterior scalp. When light strikes the front bald scalp it tends to reflect glaringly at the missing hairline where the horizontal and vertical planes of the scalp meet. Similarly, in the back of the head the missing hair creates a stark baldness when light strikes this intersection of two planes. Accordingly, the VTZ is a very important area to create density to reduce the illusion of baldness in this area. Further because the grafts are placed at the beginning of the horizontal plane they can serve to heighten density from even a frontal view. Stronger grafts tend to be placed there as a priority to create the posterior head frame, or least should be considered a priority after other strategic zones are met, like the anterior hairline and central forelock, etc.
The angles of the recipient sites and the grafts placed into the recipient sites should be in a slight radial fashion to match the transition from the radial crown to the relatively straight forward directed posterior midscalp sites. The radial splaying progressively becomes less apparent row by row going forward as the crown blends into the posterior midscalp. The lateral or outer sides of the VTZ have a more accentuated outward-radial pattern as they blend into the posterior portion of the lateral humps, or outer temporal areas. These subtleties are meant more for the surgeon to understand but are offered up for the reader for sake of completeness and for a thorough understanding of the VTZ and its role in a hair transplant procedure.
Samuel M. Lam, MD, FACS is a board certified hair restoration surgeon specializing in hair transplant procedures for men and women. To learn more about Dr Lam’s hair restoration procedures please visit our website hairtx.com or call 1-888-866-3388 to schedule a consultation.