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Trasplante de cabello

Safe donor site management

One of the most important factors in successful hair restoration surgery is the efficient use of the donor area when restoring a patient’s hair situation. To be able to accomplish “safe” donor site management, the hair surgeon needs to understand how to plan and evaluate the patient’s donor area carefully without risking visible thinning of the donor site. This requires meticulous measurements and is relevant to the hair surgeon’s extensive skills and expertise. There are several factors that influence the safe donor site management. 

The influence of the following factors is decisive in donor site management and need to be taken into consideration:

1. The hair characteristics

  • Hair colour (vs. skin tone)
  • Hair length 
  • Hair thickness 
  • Hair structure 
  • Hair quality
    1. FUD (hair per FU), MUG/MFUG (multiple FU groups) and hair mass index
    2. Miniaturization/ percentage of telogene follicles (especially in the low and high fringe regions)
  • Hair direction and angulation

2. The skin type

The micro scars are more visible in patients with dark skin, especially in patients with skin type IV and V in the Fitzpatrick scale


3. The surface of the donor area 

The ‘safe’ donor area

The presumed permanent ‘safe’ donor margins have been defined by several physicians in hair restoration and Dr. Alt and Dr. Unger’s recommendations have been used as a guideline for decades. There is however no fixed rule in defining the permanent safety zone and it is impossible to predict the donor graft behaviour in all patients, especially in case of young patients. In Follicular Unit Extraction we are inclined to refer to donor area as a gradient of risk: 

  • Areas of low risk or ‘major’ donor areas: the surface that lies within the presumed safe donor of the occipital and temporal area
  • Areas of high risk or ‘minor’ donor areas: the surface that lies beyond the presumed safe donor area, harvesting from these regions is less reliable and increases the risk of only temporary survival of the transplanted follicular units, patients who suffer from severe hair loss are very likely to lose hair in these regions when aging. The follicular units are more susceptible to hair loss and contain a higher number of telogene follicles
  • The gradient can be expanded and more specified into areas of mild or moderate risk and even into negligent areas. 

Preoperative shave: Full short haircut vs. macrolines

In case of a short haircut, the hair surgeon could make optimal use of the full donor area. Micro- or macrolines on the contrary impose the hair surgeon to harvest from a smaller donor surface, which limits not only the total number of follicular units available for extraction per session but may also cause (more) visible thinning in those areas.

4. The different anatomical areas for dissection/extraction

Hair density mostly varies throughout the donor area, with lower densities in the temporal and parietal regions, and increasing densities in the mid-occipital and occipital region. Hair thickness, length, angulation and direction also varies in each region of the donor area. Follicular units are mainly harvested from the occipital region because these hairs have fewer androgen receptors and therefore experience less androgenic loss. Temporal hairs are often thinner so harvesting should be done even more carefully to prevent visible thinning. It is important to ‘feather out’ harvesting in the low fringe area as the micro scars are oval due to a longer incision length and are therefore more perceptible after surgery.

5. The extraction punch

The FUE punch is a very important factor in donor site management.

Different factors influence the quality and size of the extraction:

  • The punch diameter:
    • The inner diameter
    •  The outer diameter
    • The cutting edge diameter
  • The cutting edge: 
    •  Inside bevel punch
    • Middle bevel punch
    • Outside bevel punch
  • The diameter of the cutting edge:
    • Small punch 
    • Medium punch
    • Large punch
  • Sharpness of the punch edge (blunt/dull or sharp)

6. The extraction technique (depth, density of extraction/cm², pattern)

The extraction technique is one of the most important and decisive factors in any hair transplant. The focus is not on extracting as many grafts as possible, but on the quality of the extraction defines in large measure the success of the surgery.  

Depth of the incision

The depth of the donor follicles varies from person to person and can even vary depending on the area of the scalp, as well as with hair characteristics. It's an important factor in good donor site management to understand this aspect otherwise transection can increase, so depth should be well considered in order to extract the follicular units without transection. With the first few punches made by the hair surgeon, he will be able to perceive the depth of the follicular units. A deeper incision is often required to remove the follicular unit during the extraction process. The deeper the incision, the higher the risk for transection. 

Density of extraction/cm²

High extraction densities per cm² should be avoided to prevent overharvesting, extraction in various densities per cm² is a good strategy to avoid visible thinning. The hair surgeon is only able to harvest a restricted number of FU per cm² per FUE session, depending on the patient‘s individual hair density in each part of the donor region. In view of the fact that small follicular unit groups and lower densities are mostly on the temporal/parietal regions, it is predominant to harvest less FU per cm² in those regions. Given the fact that larger follicular unit groups and higher densities are generally in the occipital region, it allows the hair surgeon to remove more FU/cm² from this part of the donor area.

The extraction pattern
Creating an aesthetical "invisible“ donor site:

  • No extraction in ‘Macro-/Micro-lines’ or small extraction areas (always use the full donor area)
  • No use of ‘big’ punch sizes (try to avoid punch sizes larger than ø0.90mm)
  • No extraction of adjacent FU‘s
  • No extraction in vertical or horizontal ‘lines’ (selection of FU‘s in randomized pattern)
  • No strong/sharp extractions at the borderlines of the extraction zone (creating soft „feather zones“ of extraction on the borderlines of the extraction zones)
  • No uniform extraction density per cm² (varying the extraction density of 10-20 FU/cm2 depending on hair characteristics like amount of FU, hair angulation and anatomical region -parietal/occipital/ lower neck)