What are Lateral Slits?
The use of lateral slits or, The lateral slit technique, is a method for creating recipient sites in areas of hair loss for the purpose of surgical hair transplantation. Hair grafts that are prepared through extraction via FUSS or FUE are placed into these lateral slits with small forceps either by technicians or by a doctor.
How Are Lateral Slits made?
By definition, lateral slits are hair transplant recipient sites made with custom cut "beaver" blades which are basically nothing more than raw, uncut medical grade razor blades. These are hardier and thicker, but sharper than traditional razor blades that you will find at your local grocer in the grooming section. The blades are custom sized to match the size of the follicular units that are being placed into the scalp. By customizing the size of the blade the recipient sites themselves are custom sized for the grafts. This is the first and only fully customized hair transplant recipient site creation method in existence. Every other manner of recipient site creation uses pre-fabricated needles of 18g, 19g, 21g, 23g, and sometimes 25g. While this covers the wide range of graft sizes it is not a truly customized approach. The same is true for all manner of implanter pens on the market as they too use needles.
The incision themselves are created in such a manner that they allow for multi-hair grafts to "splay" or spread once they are inserted. This effect created with lateral slits is compared to the tail of a peacock and when thousands of multi-hair grafts are placed on a balding scalp this creates a shingling effect that mimics tiles on a roof. This effectively allows for more coverage, graft for graft, than compared to other methods. This can only be achieved when the incision is made perpendicular to the direction of growth.
Lateral Slits And Coronal Angle Grafting
In 2004, during the ISHRS conference, Dr. Walter Unger proposed that the lateral slit technique be referred to as "coronal angle grafting" but this suggestion revealed that Dr. Unger did not understand the lateral slit technique. During descriptions of lateral slit technique it has been said that incisions are made in a coronal fashion, referring to the "coronal plane" of human physiology but this is incorrect. The perpendicular nature of recipient site creation is in relation to the direction of intended growth, regardless of which plane the incisions are made. This is evidenced in various areas of the scalp as natural hair direction changes drastically on various parts of the scalp. Lateral slits are made perpendicular to these various and changing hair growth directions.
The lateral slit technique was invented in 1996 by Dr. Jerry Wong in Vancouver, British Columbia Canada. Dr. Wong mentioned that the idea of using needles to place grafts never appeared as natural as he expected during his hair transplant training and he says that the idea of changing the direction of the incision came to him during a dream. The next day he turned his recipient creating needle 45 degrees to make an incision that was perpendicular to the direction of growth and he felt that the placement not only looked more natural but it allowed for better control of the angle and the direction of the graft. With further experimentation Dr. Wong discovered that the use of flat blades that were custom sized for the grafts were much better at controlling these angles and directions. In the early days of the lateral slit technique Dr. Wong had to modify a pair of garden shears to allow him to cut his blades. It wasn't until his partner devised a more refined cutting device that the lateral slit technique became more efficient and accepted in the industry. This contribution was the catalyst for pushing the lateral slit technique as a major improvement in the field of surgical hair restoration. The development of the lateral slit technique is recognized as one of the greatest innovations since the advent of follicular unit grafting and is one reason why Dr. Wong is one of only two Golden Follicle award winners in Canada.
What Are The disadvantages of Lateral Slits?
Lateral slits have demonstrated advantages but there are also some disadvantages.
- The technique itself is considered to be "counter intuitive". The procedure does not come naturally to hair transplant surgeons that are used to creating sagittal incisions thus the learning curve is more steep.
- The potential for unnecessary trauma is greater than with sagittal incisions. Lateral slits cut more blood vessels during the recipient site creation stage of a hair transplant and when inexperienced hands attempt dense packing excessive trauma to the recipient scalp can develop with some cases resulting in isolated necrotic formation.
- Density is achieved through dense packing and not through the number of hairs. Top lateral slit practioners will sometimes sub-divide the grafts from three and four hair grafts down to single and double hair grafts. This allows for smaller incisions which helps naturalness but it means incisions must be placed closer together. This can lead to increased trauma and potential for infection. When performed properly the density is very natural but the graft count to achieve this density is elevated artificially.
What Are The Advantages of Lateral Slits?
Some of the advantages of lateral slits are:
- Some have argued that because of the more shallow nature of the incision made with lateral slits compared to sagittal slits that even with additional blood vessel damage the incision is more shallow thus the trauma is avoided.
- Better coverage over a given area compared to sagittal incisions due to the "shingling effect" that is created by the nature of the incision. Part of this coverage is also achieved by modifying each multi-hair follicular unit. When follicular units are harvested, via FUE or FUSS, they can be round or oval in shape. By dissecting one side of the follicular unit the tissue spreads out and appears to be more rectangular in shape. This allows for a better fit into the incision and allows for a more natural appearance.
- The shallow nature of the incision can allow for the potential for slightly more natural results with less recipient site scar formation.
When researching hair restoration clinics it is good to know which use lateral slits and which do not but it is not to be a defining trait of the clinic you choose. The majority of top clinics in the world are not using the lateral slit technique exclusively, and in many cases not at all.