the hair shaft, i.e. just to the level of reticular dermis, the dermal attachments on the upper side are too thick for the FU to be easily pulled out. Therefore, the FU (follicular unit) breaks or can not be extracted.
If, on the other hand, one goes deeper, to reduce the dermal attachments on the upper side, the punch usually cuts one of the hair roots of the FU on the lower side. Therefore, the FU is damaged to some extent.

(2) Distortion of the FU structure- when one presses on the skin with the punch, the skin sinks. As a result the hair roots of the FU get splayed/ spread apart. This leads to an increased chance of damage to the hair roots as the punch cuts downwards.

It is because of these reasons that most ht surgeons maintain that traditional FUE leads to significant hair root damage.

In FUSE, these problems are dealt with thus:
(1) The punch goes a less deep than what would, normally, beconsidered safe. The skin depth which is not cut using the punch, is what we call the safety margin. The safety margin is deduced by titration in the initial few graft extractions. While inserting the punch, care is taken to visualize that the LOWER side of the punch goes to the mid dermis level only (irrespective of the fact that the upper side of the punch remains in upper dermis). The remainder of the FU micro dissection & extraction is done by the needle under direct magnified visualization and mild traction.
(2) Liberally infiltrating the dermis with normal saline helps in reducing the distortion of the FU due to pressure of the punch (i.e. when the punch presses down the skin does not sink too much).

In traditional FUE methods, only those patients with-
(1) Compact FUs without too much and too early a spread of the hair roots,
(2) FUs consisting of mostly straight hair,
(3) Comparatively weak dermal attachments,
get favourable results without unacceptable levels of hair root transections.

In FUSE, we deliberately limit the cutting with the punch to a higher level. The remaining dissection of the FU is done with needle under direct magnified vision before the graft is completely extracted.

In FUSE, the needle based dissection is given more importance than the use of punch. It is not sufficient that the needle be used occasionally to separate a particularly tenacious FU. Rather, the needle is deliberately and regularly used for the final in vivo dissection of the dermal attachments of the FUs.

We believe too that exerting mild traction on the follicular unit, before using the needle, brings the hair roots closer together. This further reduces the chance of hair root transection.

Thus, FUSE provides a much safer method of extracting FUs compared to traditional FUE methods. Numerous respected hair transplant surgeons have valid doubts about FUE leading to increased hair root transaction. They are entirely justified in that respect. But the way forward is not to stop our attempts of individual follicular unit extraction but rather to improve techniques so that hair root transections are limited to negligible levels.