Dr.Bijan presented a report on the terminology that is used in FUE transplantation by presenting the definitions commonly adopted by international surgeons.
Here is a brief summary written by BOLA..
TRANSECTION: We speak of transection to report any microscopically visible rupture of a follicle along its length. A follicular unit may undergo partial or complete transection.
PARTIAL TRANSECTION: refers to a follicular unit that has one or more follicles that have been transversely cut but still retains intact follicles.
TOTAL TRANSECTION: amputation of all follicles present within a follicular unit that therefore has no intact follicles after extraction.
FOLLICLE TRANSECTION RATE (FTR): E‘ the value that is obtained by dividing the number of follicles that have undergone transection multiplied by 100 by the total number of follicles that have been extracted (both those intact and those that have undergone transection)
PARTIAL TRANSECTION RATE (PTR):This is the value obtained by dividing the number of follicular units that underwent partial transection multiplied by 100 by the total number of follicular units that were extracted.
PARING:This is a situation in which the connective tissue sheath, or the outer or inner epithelial sheath, are torn longitudinally by the sharp edge of the punch. The image below provides an example of paring.
CAPPING: This is a situation that occurs when after making the incision with the punch to extract a particular follicular unit at the time of using forceps to remove it, only a small portion of tissue (epidermis or dermis) is obtained without terminal capillary follicles that remain within the donor area instead. In many cases this is due to failure to achieve the necessary depth of incision with the punch in order to release the follicular unit. In other cases, capping may occur because sufficient force was not applied in the extraction or because of improper forceps positioning at the time of extraction. In some cases with the small portion of tissue, vellus or telogen hair may also be harvested.
PLUCK: This term is used to define one or more terminal hairs removed by pulling a follicular cluster with tweezers with the goal of extracting viable follicles from the donor area in order to graft them into the recipient area. A torn hair (pluck) may include one or more “naked” follicles lacking all components of the connective tissue sheath, outer and/or inner epithelial sheath, or dermal papilla.
In some cases, torn hair may have only part of these sheaths. In some situations only the inner epithelial sheath remains. Usually when the distal part of the outer epithelial sheath remains in the donor area following “tearing” the dermal papilla also remains in the donor area and is not removed.
BURIED GRAFT (U.F SEPOLATED): A follicular unit that is pushed too far down and remains below the surface of the skin during the attempt to cut and isolate it with a circular punch.
SPLITTING: This is called the act by which by means of the punch a part of the follicles is separated in vivo (or in situ) from a group (follicular unit or follicular family). Splitting can be produced deliberately or unintentionally. To give an example, a double follicular unit can be “split” into 2 singles.
TRIMMING: This is called the removal of the dermis and other unwanted perifollicular tissues from a follicular unit extracted via FUE. This operation is performed under a microscope and is intended to make the follicular unit thinner. The advantage of trimming is to make the unit fit into a smaller incision, reducing the volume of tissue inserted into the recipient site, avoiding volumetric expansion of the recipient area (unwanted skin ridging-lifting)
SPLAY: Describes the divergence of one follicle from another; typically occurs in the lower third of a follicular unit
FOLLICULAR UNIT ANCHOR SYSTEM (ANCHOR SYSTEM): This is the set of structures that prevent the extraction of the follicular unit from the surrounding tissue. The follicular adherence includes the sebaceous gland and the insertion of the pilo errore muscle, the junctions with the dermis, and the connections between the connective tissue and the surrounding fatty tissue.
CALCULATED DENSITY IN DONOR AREA: This is the ratio of the number of hairs that can be counted in the donor area to the number of follicular units present in that same area of the donor area. (This value can be obtained by making use of a dermatoscope)
ROTATORY EXTRACTION: With this extraction technique, the punch rotates repetitively making a 360-degree turn as it penetrates the skin. This type of extraction is usually done with motorized punch.
OSCILLATORY EXTRACTION: The punch is rotated back and forth at different angles and revolutions per minute (RPM) during penetration. This type of extraction can be performed with a manual or micromotor punch.
THICKNESS CONTROL: This refers to the use of different accessories together or around the punch to precisely calculate the depth of punch insertion into the scalp. Usually the punch is inserted 2-3 mm to free the follicular unit from the surrounding tissue with the help of tweezers. Extracting to a shallower depth minimizes the risk of transection. The depth depends on the different areas of the scalp where extraction is performed.