FUE Transection
Dr. Alan Feller
There are two distinct types of transection inherent to FUE. The
first is the application of a punch “off angle” to the target FU.
This will result in a slanted slice right through part or the whole
of the FU. The other type of transection is not so obvious.
During my first FUEs I noticed that I was getting a large number of
successful deliveries, but under the microscope I noted that many of
these grafts had partially transected bulbs in the lateral aspects.
That is, in a three haired FU, I would successfully extract the FU,
but only the center graft was intact. At first I though it was the
result of poor angulation, but upon close inspection I realized this
was not possible. While an “off angle” attempt may result in the
transection of one side of a (planar) 3 haired graft, it didn’t
explain why the other side was also cut.
If the geometry of the scenario is considered schematically, logic
demands that the opposite side follicle not only be untouched, but
given an extra bit of room of safety directly proportional to that
of the transected side. In other words, only one side can be
transected, not both, but this was not the case. Both sides were
consistently transected. Furthermore, it happened often enough for
me to realize that I couldn’t just by mere chance be shaving the
graft so close as to injure the follicle but not the nearby dermis,
time and time again. No, something else had to be happening. Then it
became clear.
Torsional or linear tearing was probably the root cause of this
root problem. As the punch travels down the dermis there is a
frictional component created by the wall of the punch, both static
and dynamic. To decrease the linear friction, which is easily
detected by even an amateurs hand, we tend to rotate the punch so
that it will proceed faster and easier through the skin. However,
this now introduces a torsional component, that combined with
friction creates a shearing force that I suspect rips the lateral
and poorly supported deep follicles and bulbs off the body of the
graft. This explains why both sides would suffer “transection” but
not the center.
This torsional phenomena probably occurred with the larger punch
grafting, but was ignored due to the relatively small amount of
damaged lateral follicles compared to the safe and intact core
follicles.
.
To reduce the amount of torsional transection, it is helpful to
reduce the spinning of the punch to more of a reciprocating action.
Even better is to use a punch whose walls are slightly greater in
diameter to the cutting edge. This will decrease friction and “grab”
of the graft during extraction.
It is also helpful to punch down to a slightly more shallow depth
during the scoring process and rely more on the perforation
technique to release the graft for delivery. This is accomplished
with practice.
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