Dorsum and osteotomies — Lowering the hump without losing the lines or the valve
Component reduction versus en bloc resection, the reference level and why the rhinion rules, the three osteotomies and their traps, closing the open roof and dorsal preservation techniques.
Content intended for healthcare professionals. It does not replace clinical assessment and is not written as patient information.
Key points
- Small resections have large effects. That sentence sums up the whole chapter: it is always preferable to fall short and adjust afterwards with a rasp than to overdo it and have to rebuild.
- The hump has a bony and a cartilaginous component in different proportions in each nose. Treating them separately — component reduction — is what preserves the dorsal aesthetic lines.
- The rhinion should remain the most prominent point of the dorsum, with the supratip slightly below to accommodate skin retraction. That is the reference level, not a uniform straight line.
- Removing the hump opens the roof and widens the nose. Osteotomies are not an aesthetic extra: they are the manoeuvre that rebuilds the bony roof, and must be bilateral and symmetrical or the result will be worse than the starting point.
- The inverted-V deformity is the characteristic sequela of this stage: it appears when the upper laterals collapse medially as the bones are mobilised. It is prevented, not corrected.
What exactly the dorsum is
The dorsum is formed by the upper lateral cartilages inserted on the anterior septal border and, above them, the nasal bones and the ascending processes of the maxilla. The zone where the two overlap — the keystone area — is not a simple boundary: the upper laterals tuck under the nasal bones for several millimetres, and that junction is what keeps the middle third open. A prominent dorsum may present as a continuously elevated line — rhinokyphosis — or as a true hump, an elevation preceded and followed by a depression. The proportion of bone and cartilage varies widely: in short noses it is usually mostly cartilaginous, so once a minimal bony excess is rasped the rest is resolved with a blade. Knowing that proportion before starting is what prevents reaching for the mallet where a 15 blade would have done.
How much to lower decides what to lower it with
- Minimal excess, up to 3 mmCareful rasping of the bone. The rasp is held perpendicular to the long axis of the nose and cuts only with its anterior part, so as not to damage the cartilage or tear the delicate osseocartilaginous attachments. The upper lateral–septal junction may be preserved or lowered with a blade
- Short noseOnly a small part of the hump is bony. That minimum is rasped and the rest is remodelled directly with a blade on the cartilaginous component
- Larger reductionSubmucous technique: tunnels on each side of the anterior septum releasing the perichondrium of the internal dorsal vault and the anterior borders of the upper laterals, with the subperiosteal plane extended over the bony dorsum
- Large bony humpA guarded osteotome with blunt edges and the bevel facing down, so it does not tend to dive. Or piezoelectric instrumentation, which cuts bone without injuring soft tissue. The rasp allows more precision than the osteotome but is far slower
By components, not en bloc
En bloc resection of the upper lateral vault together with the anterior septal border is quick, but it treats as one piece three structures with different thicknesses and behaviours, and is the classic way to lose the dorsal aesthetic lines in a single stroke. The alternative — doing it step by step — means first separating the upper laterals from the septum submucously, hugging the septum so as to resect as little upper lateral as possible, then judging with the structures individualised how much anterior septum is truly redundant, and only then addressing bone. It is slower and allows correction as you go. It also keeps open the most valuable option: not resecting the upper laterals so they can serve as spreader flaps, which is exactly what will be needed minutes later to close the roof.
Where to set the level
The reference for deciding how much to lower is the facial plane, not the eye over the field. And on that reference two rules order the profile. First: the rhinion, the osseocartilaginous junction, must remain the most prominent point of the dorsum; lowered below the line, the middle-third depression appears that no later manoeuvre fully repairs. Second: at the supratip, room must be left for skin retraction, because the soft tissue is thicker there and accumulates over time; a dorsum perfectly straight in theatre ends up with supratip fullness at six months. There is also a difference of taste worth stating because it changes the amount resected: a few millimetres more are removed in women to leave a slightly concave dorsum, and less in men to leave it straight.
The check after resecting
- If an osteotome was used, look at the fragment removed: its bone-to-cartilage proportion varies greatly between cases and tells you whether you resected where you thought.
- Wet the dorsal skin and run your fingers over it. This is the manoeuvre that detects irregularities the eye misses with a dry field and undermined skin.
- The final gentle rasping evens out the bony dorsum and removes edges that in thin skin will show through months later.
- Recheck the dorsum after the osteotomies and again after placing the spreaders: each of those manoeuvres can create a new osseocartilaginous interference.
The three osteotomies
| Osteotomy | Course | What for |
|---|---|---|
| Medial (or medial oblique) | The osteotome parallel to the septum at the lower border of the bony defect, struck at about 30° upward and outward until the change in sound on reaching denser bone | It defines the final dorsal width: the defect must be equally wide on both sides. Always necessary when a significant hump has been removed |
| Transverse | At the level of the medial canthus, slightly below the nasofrontal suture. This is where perforating vessels are found | It is the upper hinge: without it the fracture propagates unpredictably and may reach the frontal bone |
| Lateral (low-to-low) | Over the ascending process of the maxilla, from the piriform aperture up to meet the transverse cut. It describes a curve: first outward and upward, then upward and inward following the bone | It is the one that allows the roof to close. The lower the better: it leaves a less palpable step and a narrower dorsum |
| Multiple laterals | Several levels of lateral osteotomy on the same side | Markedly deviated or very broad noses, where a single fracture does not mobilise the lateral wall enough |
Details of the lateral osteotomy
- The approach may be internal — a minimal vestibular mucosal incision below the piriform aperture and anterior to the turbinate, without elevating periosteum — or transcutaneous, through a minimal lateral skin incision with a 3 mm osteotome making small fractures that are then joined.
- Sound informs: low down, where the bone is thin, the osteotomy advances easily; higher up the thickness increases, progress slows and the pitch changes. That is the signal that solid bone has been reached.
- The base of the piriform aperture — Webster’s triangle — is spared, because including that fragment in the fracture narrows the vestibule and compromises the airway.
- Infracture is done with the fingers, index and thumb. It must be complete, symmetrical and without resistance; a small crack is even heard. If there is resistance the fracture is incomplete, and forcing it is what produces asymmetry.
- Loose bone fragments left behind will widen the dorsum later: complete the fracture with a horizontal osteotomy at the radix or with the medial cut. And if a palpable step remains, burr it down.
The inverted-V deformity
When continuity between the upper laterals and the septum has been interrupted, the upper laterals are supported only by the caudal borders of the nasal bones. As the bones are moved medially by the osteotomies, those attachments drag the upper laterals towards the septum. If the bones are short, or if those attachments were lost during dissection, the medial collapse is excessive: the internal valve narrows — with the functional consequence — and a visible step appears at the caudal border of the bones, the inverted-V deformity. The approach is to anticipate: when it is suspected, or already evident intraoperatively, spreader grafts are placed to reposition the upper laterals. This is why in current practice spreaders routinely accompany a significant dorsal reduction.
Dorsal preservation: when the hump is not removed but lowered
The logic above — resect then rebuild — has an alternative that has returned strongly in the last decade: do not open the roof. In preservation techniques the osseocartilaginous vault is kept intact and lowered as a block, resecting from beneath: a subdorsal strip of septal cartilage and, depending on the variant, a bony strip at the base — let-down — or simply release of the pyramid to sink it — push-down. The advantage is direct: there is no open roof, no upper lateral–septal junction to rebuild, and the dorsal aesthetic lines have never been touched, so the risk of dorsal irregularity and inverted-V disappears. So do the drawbacks: the technique depends heavily on radix shape and septal deviation, is less versatile with very large humps or deviated dorsa, and has its own learning curve and its own recurrences. In practice both families coexist, and the sensible approach is to choose by case rather than by school: preservation when the dorsum is harmonious and only too high, structured resection when the shape of the dorsum must be redesigned.
The nasofrontal angle and procerus
Not all of the upper profile is bone. Procerus contributes to reducing the nasofrontal angle, and when that angle appears very open because of muscular hypertrophy, resecting the muscle at the glabella corrects it without touching the skeleton. It is worth discussing beforehand with the patient, because it produces striking postoperative bruising in the area that alarms without being serious. In the other direction, if the radix is low the manoeuvre is additive — a radix graft — not subtractive, and it should be decided before starting to lower the dorsum: a low radix makes the hump look bigger than it is, and whoever fails to assess it ends up resecting dorsum that was not redundant.
When to perform the osteotomies
Is septal graft needed in this operation?
Is the dorsum already regularised with only narrowing left?
What prevents the dorsum from narrowing
If after correct osteotomies the dorsum is still wide, there are two usual suspects before repeating the fracture. First: the medial osteotomy defect is not equally wide on both sides, so one lateral wall moves in and the other does not. Second, quieter: a wide, T-shaped anterior septal border acting as a physical stop that prevents the bony plates from approximating or makes them do so asymmetrically. Checking and thinning that border before insisting with the mallet saves unnecessary fractures. And a third option when an even narrower bony dorsum is sought: two fine burr holes in the remaining nasal bones and a 4/0 PDS stitch to approximate them in a controlled way, instead of forcing the fracture further.
References
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Related specialty: Rhinoplasty