August 23, 2018 Perhaps there is no other area in aesthetics where science and artistry and joined by the hip (or in this case hair) than hair restoration. Hair restoration often involves a calculation of number of hairs to be harvested and removed from a donor area. What is frustrating to most patients is that in most practices, very little calculations seem to take place and just broad estimates are taking place. Even in painting a house or placing new flooring, an EXACT measure is necessary, why would your hair be any different. So we present some of the thought process necessary in our practice to create elegant hairlines- at least the mathematical portions.Hair PatternIn my practice, hair is harvested exclusively with robotics. This ensures that some of the calculations correlated with the hair trichoscopy are accurate. The ARTAS Robot (see picture) will demonstrate the hair density of a given area of hair. Based on this hair density, I will adjust the amount of grafts harvested to provide coverage. Typically, 50% of hairs are thought to prevent see through areas. One major disadvantage of removing the hair by hand is that a calculation must be made on each graft to ensure that the hair will not be overly harvested.The number of follicles per sq cm is detected by the ARTAS. The ARTAS can then be adjusted to harvest more or less per sq cm depending on each case.The hair quality factor is a proprietary number based on the quality of the hair (caliber, waviness, color hair vs scalp) to help standardize a calculation on how much hair can be harvested for a given patient. For example a patient with extremely wavy hair which is medium colored and thick can have more hair harvested per sq cm than a patient with thin, dark hair. The “Aesthetic Scalp %” is also a proprietary number we use for our hair cases based on our data to determine the optimal donor density. In some practices, 50% coverage is OK. Based on our hair experience and data, my practice has a specific percentage that provides coverage guidelines. The advantage of the ARTAS system is that all of these variables can be adjusted. Removing hair by hand, even with an experienced technician can lead to small patches of alopecia which can lead to see through with a variety of hair styles. PHOTO COURTESY OF REAL SELF – NOT A PATIENT OF DR SHAH However, see through can occur when transitions to other areas of the hair are not accounted for as well. In addition, see through can occur when the pattern of removal is too predictable and the eye can detect the pattern. Removing the hair by hand the technician must be able to do an irregularly irregular pattern of removal. Let’s explain the difference between irregularly irregular and a visible pattern. In this diagram, you can see that if every third hair is harvested, a visible pattern will be seen by the eye and patients can have detectable sign of harvesting. With an irregular pattern of hair removed, the pattern is undetectable to the human eye since the pattern is not recognizable. Harvesting hair is much more than preventing see-through. Obtaining quality hair grafts (which the ARTAS in my opinion is the best at in the world based on our data and having used a variety of systems available), avoiding shock loss , and using regenerative factors are also critical to the success of your hair loss. While this might be a bit technical and mathematical for some, it does give insight into the thought process on how Aesthetic Scalp attempts to improve the consistency of hair transplantation.