Q: When a donor strip is taken out during a hair transplant and separated under the microscope, you can read on the internet that there is a wastage of grafts (about 15%), because of those unseen telogen hairs. What do you think about that and how does it affect the hair restoration?
A: The Telogen phase of the hair cycle is about 3 months long and about 12% of follicles are in this phase at any one time. It is speculated that the follicles may be empty for perhaps 1/2 that time (this number may vary significantly between people). Therefore, approximately 6% of the hair follicles may be in telogen at any one time.
On average about 15% of the follicular units are 1-hair units (but this also may very greatly between patients). If 6% of all follicles are “empty” telogen follicles, then there should be .15 x .06 = .009 or about 1% of the patient’s 1-hair follicular units in the empty telogen phase that can’t be identified and will be missed on dissection.
The 1% isn’t very large. However, also consider that the remaining 5% of the empty follicles are associated with larger follicular units (i.e. those with 2-4 hairs). If these follicular unit grafts are closely trimmed, as is the practice with very dense packing, a much more significant number of follicles are at risk of being lost. With chubby follicular unit grafts (i.e., where the microscopic dissection leaves a protective sheath of tissue around the follicles) the risk should be closer to the 1%.
The lesson for hair transplantation is that over-trimming of grafts, for the sake of very dense packing, may waste telogen hairs as well as place the grafts at an unnecessary risk of mechanical trauma, drying and warming.
Topic: Graft NumbersTags: Dense Packing of Grafts / Dermal Sheath / Desiccation / Donor Hair / Follicular Unit / Hair Cycle / Mechanical Trauma / One-hair Follicular Unit / Telogen Phase
Posted by Robert M. Bernstein M.D. at 11:39 am
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