Graft Distribution Maps: Allocating Grafts Across Zones

Two surgeons quote the same patient 3,200 grafts. One commits 1,900 of them to the frontal third and leaves the crown alone; the other spreads the same number evenly across everything that looks thin under clinic lighting. Both operations are technically clean, and at four months both patients are pleased. At three years the second patient has a uniformly translucent scalp, no framing at the front and no donor left to correct either. Graft distribution planning is the step between agreeing a number and deciding where each hundred of those grafts goes, and it shapes the result more reliably than surgical technique does.

The reason is arithmetic rather than artistry. Survival differences between competent operators sit inside a fairly narrow band. The difference between committing 60% of a budget to the frontal third and committing 25% is visible across a room, and it is permanent, because grafts placed in the wrong zone are not merely wasted — they are subtracted from a supply that never refills.

What a distribution map actually is#

A distribution map is a document, not an intention. At minimum it carries marked zone boundaries, the measured area of each zone in square centimetres, a planned density, an allocated graft count, an assumption about hairs per graft, and the reserve deliberately withheld. It is dated, initialled and photographed alongside the marked scalp. Clinics that keep this record can explain any allocation decision two years later; clinics that keep only a graft number and a price cannot.

Zone definitions should be standardised across the practice so that two surgeons measuring the same head produce comparable numbers. The workable division is six zones, and they do not carry equal value.

Two rows in that table drive most planning disputes. The frontal third is small and cheap to make convincing. The crown is large, expands with age, and consumes grafts at a rate few patients anticipate when they ask for it.

Frontal versus crown allocation, settled properly#

The frontal vs crown allocation argument recurs at nearly every consultation, and it is usually framed as a matter of taste. It is not. The frontal third frames the face, carries every photograph, and — critically — sits in territory the patient has already lost, so it will not expand much further. The crown behaves in the opposite way: a vertex that measures roughly 20 cm² at Norwood IV can approach 60–70 cm² by Norwood VI, tripling the graft requirement for the same visual outcome while the donor stays fixed.

Here is where the conventional teaching is wrong. The common belief is that grafting the crown is itself the error. It is not; a mature patient with a stable pattern, a generous donor and a secured hairline is a perfectly reasonable crown candidate. The error is allocating against the pattern in front of you rather than the pattern the patient will have at sixty. A Norwood IV treated as a Norwood IV becomes a Norwood VI with an island of transplanted vertex and nothing to bridge it. Every allocation decision should be tested against the worst plausible progression, not the current photograph.

Percentages are of the session budget, not of the donor. The reserve column refers to lifetime harvestable units, and it is the number most often written down and then quietly spent.

Graft distribution planning across a lifetime, not a session#

Treat the first operation as one instalment in a plan that runs twenty years. That reframing changes three decisions. Density in the frontal third is planned to survive a second pass rather than to maximise the twelve-month photograph. The midscalp is left deliberately transitional so a later session can extend backwards without a visible seam. And the crown is either committed to properly or left entirely alone, because a half-covered vertex is worse than an untouched one.

Medical therapy belongs inside the map rather than beside it. Grafts can be allocated differently for a patient stable on treatment than for one who declines it, and that difference should be written down at the time. Our overview of medical management for hair loss covers what stabilisation realistically achieves; for planning purposes, the practical point is that an untreated patient needs a more conservative distribution and a larger reserve, not more grafts.

The other lifetime input is survival. Allocation assumes that placed grafts grow, and the honest planning figure sits below what most clinic marketing implies. The variables that move it are set out in our review of graft survival in FUE and DHI; a plan built on an optimistic survival assumption is a plan that under-delivers in the last zone on the map.

The temples, the zone most budgets omit#

Temporal recession is the most under-allocated area in routine graft distribution planning. It is easy to see why: the temples sit at the edge of the marked field, they are usually assigned last, and a patient looking straight into a mirror rarely notices them. In three-quarter view and in photographs they dominate, because the temporal points anchor the whole frame of the face.

The zone is also unusually efficient. Ten to fifteen square centimetres a side, planned at 25–35 FU/cm² with fine single and double units, converts a hairline that reads as transplanted into one that reads as intact. Six hundred grafts spent there frequently buy more perceived improvement than the same six hundred added to a midscalp that already has native coverage.

Two cautions apply. The first is angulation: temporal hair grows acutely, close to flat against the scalp, so sites cut at frontal angles produce a tufted edge that no amount of density hides. The second is progression, because temporal recession continues in most male patients, and an aggressively rebuilt temporal point is a commitment to maintain it later.

Where zone allocation goes wrong in theatre#

Most distribution failures are not planning failures. They are execution drift. Site creation runs slightly denser than planned in the first zone because the surgeon is fresh and the tissue is cooperative. Two hundred grafts disappear into that generosity. By the time the team reaches the final zone, the shortfall is real and the choices are all bad.

Three habits prevent it. Count sites per zone before placing anything, rather than counting grafts afterwards. Sequence the list so any shortfall lands in the lowest-priority zone — build the hairline and frontal third first and work backwards. And treat the zone allocation of grafts as a hard boundary during the operating day, with any reallocation requiring an explicit decision by the surgeon rather than a technician's judgement under time pressure.

Patient pressure mid-procedure deserves its own rule. A patient who asks for a little more in the crown while sedated is not in a position to consent to spending reserve, and the surgeon who agrees is trading a documented plan for a conversation nobody recorded. If graft distribution planning is to mean anything, the map has to outrank the operating day.

Documenting the plan so it survives the follow-up#

Photograph the markings before shaving, from the same five angles used for outcome photography, and file the map with them. Standardised imaging is what allows an allocation decision to be audited rather than remembered; our guidance on before-and-after photography standards sets out the conditions that make serial comparison meaningful. Note that advertising rules governing how those images may be used vary by jurisdiction — verify the position with your regulator, professional body or indemnity insurer before any image leaves the file.

Revise the map at each review and formally at twelve to eighteen months, when the result is mature and the donor has recovered. Distribution is a design decision as much as an arithmetic one, and the geometry that governs the front is covered in our hairline design principles; the map tells you how many grafts that design is allowed to consume.

Sources and further reading#

• Norwood OT. Male pattern baldness: classification and incidence. Southern Medical Journal. 1975;68(11):1359–1365.
• Parsley WM, Perez-Meza D. Review of factors affecting the growth and survival of follicular grafts. Journal of Cutaneous and Aesthetic Surgery. 2010;3(2):69–75.