Nasal function is comprised of air-conditioning (heating, humidifying), filtration, and smell. The different parts of the nasal airways from the nostrils to the nasopharynx contribute in specific ways to the overall task. The bony pyramid is part of the external nose and has close relationships to the septodorsal cartilage (septal cartilage and upper lateral cartilages) and the perpendicular plate. While most of the nasal functions are related to the infrastructure of the nasal cavity and especially the mucosa, the pyramid has specific tasks in inspiration and expiration. The inspired air is directed in a proper way to the nasal cavity and the airstream divided in two more or less equal bilateral volumes. Important functional areas are the nasal vestibule and the nasal valve area with the head of the inferior turbinates. Since the upper lateral cartilages are just the cartilaginous extensions of the nasal bones, they contribute to the nasal valve cross-sectional area (“bone dominates cartilage”). The perpendicular plate is fixed to the undersurface of the nasal bones and determines the direction of the septal cartilage. Because of these complex interrelationships between bone and cartilage of the external nose, the bony pyramid is jointly responsible for adequate distribution of air.

While the nasal valve area acts as a diffusor at inspiration and slows down the postvalve air velocity, it is also responsible for accelerating the expired air. This way, the CO₂-rich air is transported from the nostrils in order not to be inhaled again at the following inspiration.

In most of the cases, indications for bony pyramid surgery are based on abnormalities of the bony and cartilaginous vault (e.g., nasal profile). With a regular position (projection) of the nasal tip, prominences of the dorsum are called “nasal hump” and can be resected for aesthetic reasons. However, if the dorsum is very high together with a prominent tip and a narrow vault, it is part of a “tension nose” (prominent nose syndrome) and may cause functional disturbances (increased resistance at inspiration, alar collapse). After trauma or previous surgery, irregularities can also be indications for surgery.

The nasal dorsum can be straight or deviated from the midline or crooked in many variations (e.g., C-shaped, S-shaped). Because of the anatomic unit of nasal bones, upper lateral cartilages and bony as well as cartilaginous septum, all these structures have to follow the nasal bones, if they are deviated from the midline. The typical findings are a deviation of the septum with an ascending crest from the premaxilla to the vomer contralateral to the deviation of the dorsum. The end of the caudal septum is, in most cases, fixed in the midline position at the anterior nasal spine. Its caudal edge, however, is deviated in the same direction as the dorsum (subluxation). It is obvious that in patients who have a significant deviation of the nasal bones, the correction of its sequela, the septal deviation, is not sufficient. The underlying cause also has to be corrected by osteotomies.

Other indications for surgery include a wide nasal pyramid. In some cases, this may be part of larger malformations such as nasal clefts or nasal fistulas. Fistulas extend deep to the nasal bones; therefore, a temporary removal of the nasal bones provides access to the skull base. Partial transoral resection of the piriform aperture can be part of a midfacial degloving approach.

There are only a few contraindications for osteotomies or bone resections. One of them is significant disturbances in healing, for example, in immunocompromised patients. In a growing nose, osteotomies can affect a normal development. However, growth disturbances are more feared with surgery of the cartilaginous infrastructure.

Some patients claim pain in the area of the piriform aperture after previous rhinoplasty or trauma. Very often, the external nasal nerve is involved. It is the terminal branch of the anterior ethmoidal nerve and leaves the nasal cavity between the nasal bones and the upper lateral cartilages. The nerve may be imbedded in scars and additional surgical trauma can increase the problems. Therefore, revision surgery for release of pain is normally not indicated.

Careful preoperative examination and planning is essential, as minor deformities or even deviations of the dorsum are no longer visible, as soon as the skin is elevated and edematous. The amount of resection of the dorsum in humps or prominent noses depends primarily on the definite projection of the nasal tip. In specific situations, it is better to increase the tip projection or augment the nasion than to resect too much from the bony and cartilaginous dorsum. Very often, combined procedures with augmentation, elevation, and resection are the best solution. Computer planning can be very helpful, but the surgeon should be aware that a good surgical result is much more difficult to achieve than is generating digital images. The most critical aspect in planning is to anticipate the dynamics of the healing process. It can be reasonable to expect a decrease of tip projection
of 2 or 3 mm within 6 months and to adjust the amount of resection of the dorsum accordingly (prevention of “polly-beak deformity”).

If a prominent nasal dorsum in a tension nose has to be lowered, one can plan resections of bony wedges at the base of the nose instead of resections of the dorsum. In these patients, the skin is extremely thin and even tiny irregularities are visible. In these cases, interventions at the dorsum can be limited to paramedial osteotomies, leaving otherwise smooth bony surfaces.

In the rare case of a wide bony pyramid and piriform aperture (e.g., median nasal cleft), an intermediate osteotomy or even multiple osteotomies may be indicated. The decision is also best made preoperatively as intraoperative swelling can mimic an adequate narrowing.