Approach, incisions and undermining — What each route gains and what support it costs
The catalogue of incisions ordered by what each costs in tip support, when the external approach is justified, and undermining plane by plane with the extent each type of nose demands.
Content intended for healthcare professionals. It does not replace clinical assessment and is not written as patient information.
Key points
- Every incision is paid for in tip support. The question is not which route gives better exposure, but how much support am I willing to sacrifice and how will I restore it.
- The principle that orders the choice is old and still holds: the less surgical trauma, the better. Incisions are limited to what is strictly necessary to operate comfortably and in control.
- The external approach is not a routine method: it is reserved for situations that genuinely require it, whether primary or secondary.
- The correct plane is supraperichondrial over cartilage and subperiosteal over bone. Straying from it causes irregularities and healing problems.
- The extent of undermining decides how much the skin retracts, so it is tailored to the nose: minimal in small noses without excess skin, wide in large, drooping or thick-skinned noses.
The incision as a decision about support
The incision is only the access route, but choosing it is already a surgical decision about the tip. It can be internal, in the mucosa, or external, in the skin, and the choice depends on the areas to be treated and, no less, on each surgeon’s school and experience. What matters is knowing what each one breaks. When an incision is extended towards the membranous septum to reach the dorsum and septum, two of the major tip support mechanisms are being eliminated: the attachment of the medial crura to the caudal septal border and the support of the medial crura on the anterior nasal spine. This is not a side effect to be avoided but an unavoidable consequence of the access; what must be done is to count it into the plan and restore it afterwards with the appropriate grafts and sutures.
The incisions, ordered by what they cost
| Incision | Where it lies and what it gives | What it costs |
|---|---|---|
| Hemitransfixion | At the lower border of the membranous septum, on one side only. Access to the caudal septum, medial crura and nasal spine | It does not disturb the major support system of the tip. In exchange, it hinders access to the opposite side of the septum and can heal asymmetrically |
| Transfixion | The same, joining both sides. It can extend to the nasal spine, and to the nasal floor if more projection is sought | It eliminates the medial crural support on the caudal septum and spine. That must be restored |
| Intercartilaginous | Between the lower border of the upper lateral and the upper border of the alar cartilage, in the valve area. It gives access to tip and dorsum, and to the alars retrogradely | It sits in the valve: cicatricial retraction can alter its physiology. Do not join it to the internal osteotomy entry, and preserve the lateral end of the alars |
| Transcartilaginous | It crosses the alar cartilage, parallel to its cephalic border at 3-5 mm depending on the planned resection. It may involve mucosa only, or mucosa and cartilage | Less trauma than the intercartilaginous and, above all, it lies caudal to the valve, so it does not compromise its physiology. If only mucosa is divided, carefully elevating it on both sides allows comparison of how much cartilage to resect |
| Marginal, rim or infracartilaginous | Parallel to the caudal border of the alars, guided by the transition between hair-bearing skin and mucosa. It allows removal of fibrofatty tip tissue and cartilage weakening | It is the one always used in open rhinoplasty. Combined with the intercartilaginous it exposes the alars as a bucket-handle chondromucosal flap |
| Transcolumellar | In the columellar skin, joining the two marginal incisions. It sits at the transition or widening of the medial crural feet, extending towards the domes 2-3 mm from the skin edge | It exposes the whole skeleton. If placed closer to the face, a depressed or visible scar is risked, for lack of cartilage to resist healing tension |
To deliver or not to deliver the cartilages
This is the division that really separates approaches, more than the open-or-closed label. Those that do not deliver the alars — intercartilaginous, transcartilaginous — work on them retrogradely and preserve support; those that do deliver — double incision with bucket-handle mobilisation, or complete skin elevation — give excellent exposure and far better symmetry, at the cost of greatly disturbing the major tip support mechanisms. The practical consequence: exposure is justified when there is something to analyse, that is, asymmetry or alterations in the shape, position or consistency of the alars. Without any of that, exposure only adds cost.
Designing the transcolumellar incision
- The original was a direct transverse line. Current forms — stepped or with a midline triangular flap — allow precise closure, hide the scar and prevent transverse contracture.
- Mark the points of the design before incising: scar symmetry is decided in the drawing, not in the closure.
- The incision ends in the nasal mucosa, not in skin: that is where it continues into each marginal incision.
- The lateral extension is done with fine scissors, pulling both nostrils upward with a double hook.
Before the incision
- PositionSupine with the head slightly above heart level: it aids venous return and reduces oedema
- MarkingBiological ink — methylene blue, gentian violet or a dermographic marker — to avoid tattooing from conventional markers, applied with a sterile stick or fine brush
- InfiltrationAlways, whether general or local with sedation. Anaesthetic solution with adrenaline: it prevents bleeding and facilitates the anatomical dissection of the structures
- Where to infiltrateDorsum entering through the mucosa between lateral crus and upper lateral; tip above the intermediate crus subcutaneously; columella and anterior nasal spine; septum by direct puncture of its mucosa; the marginal area where the incision will run; and the inferior turbinates if turbinoplasty is planned
Undermining: a different plane in each territory
Undermining means separating the skin and soft tissues — fat and muscle — from the skeleton to be worked on, and the plane changes according to whether one is over cartilage or bone. Over cartilage, both at the tip and the dorsum, one works in the supraperichondrial plane, and the rule there is not to stray: leaving it produces irregularities and healing disturbances. Over the bony skeleton one moves to the subperiosteal plane with a periosteal elevator. There is an honest caveat about this last point: some object that the nasal periosteum is barely elevated at all; in practice what happens is that it is pushed superiorly to the frontonasal suture. Even so the manoeuvre is worthwhile, because it avoids damaging the periosteum with the rasp, one of the described causes of postoperative osteoma.
How much to undermine depends on the skin, not on preference
It is one of the few parameters in rhinoplasty with a clear rule: the extent of dissection determines the degree of skin retraction. Hence it is smaller in small noses, where there is no excess skin to redistribute, and wider when skin is in excess — large, long or drooping noses. Two further situations call for wide undermining: the drooping tip in which significant upward rotation is sought, because the skin must redistribute and retract postoperatively; and thick skin, for the same reason. And one exception in the opposite direction: laterally, over the ascending processes of the maxilla, it is best not to undermine, because that intact periosteum holds the fragments after the lateral fracture.
The undermining sequence
- From the lateral incisionApproach the superficial surface of the upper laterals with a 15 blade or fine scissors and undermine them to the lower border of the nasal bones, joining the dissection of both sides
- In the external approachAscend along the medial crura to the level of the domes and there find the subperichondrial plane properly before extending the dissection laterally, sliding over the alar cartilage. Countertraction with a fine hook
- Over boneChange to subperiosteal with the periosteal elevator, up to the radix and the medial canthus. Some, once bone is palpable, use a cold blade to find the plane better
- The transitionSeparate the upper laterals from the nasal bones resting on the former, remembering that the upper laterals tuck under the nasal bones
- LaterallyMinimal dissection, only what the planned dorsal reduction requires, and meticulous: this is what prevents skin adhesions to the dorsal bone
Pitanguy’s ligament: the decision that divides schools
Ascending along the medial crura in the external approach reveals the dermocartilaginous ligament, and here there is a genuine fork between surgeons with good results on both sides. Some divide it — sometimes ligating it, along with the interdomal ligament — because separating the alars this way eases the subsequent septal approach. Others always preserve it, considering it key to achieving supratip definition. There is no clear winner, so the reasonable stance is to know that a decision is being made and not to divide it by inertia: whoever preserves it gains supratip definition, whoever divides it gains access. What should not happen is cutting it without having decided.
Details that save trouble
- In open rhinoplasty, tip undermining must be particularly careful: the skin over the medial crura is delicate and alar continuity is easily broken.
- In secondary rhinoplasty it can be extremely difficult because of fibrous tissue and irregular previous dissections. Abundant infiltration in the correct plane greatly facilitates undermining.
- When elevating the perichondrium of the upper laterals towards the piriform ligament, perforating vessels appear: expect them and cauterise.
- If turbinoplasty is performed, most place it after the septoplasty and before the osteotomies. Direct scissor division increases bleeding compared with radiofrequency reduction or simple outfracture.
- And an argument for restraint with the turbinate: it serves to warm the air, and over-cauterising it is associated with more dry rhinitis.
Which approach to choose
Do the alar cartilages need analysing and modifying for asymmetry, shape, position or consistency?
Is working the cephalic portion of the alars enough?
References
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Related specialty: Rhinoplasty