The nose is made up of a fixed and rigid part that is called nasal pyramid, although it rather has the shape of a tent or roof, and a pliable mobile part which is the nasal tip, the alae and its annexes. The nasal pyramid is formed by two types of structures or tissues; in the most cephalic or upper part the nasal pyramid is formed by the nasal bones and the ascending process of the maxilla, that is, by bone tissue; the most caudal or lower part of the nasal pyramid is formed by the triangular cartilages or also called quadrangular or lateral or upper lateral, that is, by cartilaginous tissue.
Both halves or walls of the nasal pyramid join and fuse horizontally with each other in the center of the nose to form the dorsum, hump or nasal bridge (misnamed by many people as the septum, which is not part of the nasal dorsum), creating what is called pyramid or bony or osseous or hard dorsum (cephalic or upper), formed by synostosis or fusion between bones, and the cartilaginous middle vault or soft pyramid or dorsum (caudal or lower), formed by synchondrosis or fusion between cartilages. In turn, the nasal dorsum is joined and merged by its lower or posterior face with the nasal septum, nasal septum which also, in turn, consists of a cephalic or upper bony part and a caudal or lower cartilaginous part, corresponding the bony septum to the fusion with the cephalic or upper or bony dorsum and the cartilaginous septum to the fusion with the caudal or lower or cartilaginous dorsum, forming a tripod in which the lateral legs are the nasal wall and the central leg the nasal septum.
Nasal osteotomies are controlled and precision fractures with bone chisel of the nasal bones and their osseous fusions (synostosis), between them and with the maxilla and nasal septum; they are a basic and essential maneuver in the vast majority of rhinoplasties, being the refinement in their execution a critical element for achieving outstanding results after rhinoplasty, prevention of complication and absence of well known and typical postoperative deformities.
There are different kind of osteotomies; between the nasal bones and the maxilla to narrow the pyramid and close the roof after either hump resection or humpless dorsum narrowing, thus preventing at the same time open roof deformity, inverted V deformity and pinched middle vault; between both nasal bones at the dorsum to freed them from the osseous septum to prevent wrong location of the fractures and step off deformity, as well as allow smooth medialization of nasal bones; paramedial wedge or strip osseous resection in order to narrow a broad bony dorsum and prevent step off deformity; etc.
Failing to perform the osteotomies or a poor indication, planning, location or execution will certainly lead to a series of deformities, some of them mentioned above and others, thus this is a non negotiable surgical step and a fundamental skill required from the rhinoplasty surgeon; nasal bones fracturing, either infractures or outfractures, is one of the cornerstones of rhinoplasty.
Those noses with very thin dermis of nasal skin cover, scarce subcutaneous fat, already somehow transparent and showing internal natural skeletal structures through the skin, particularly at the nasal dorsum and the nasal tip, are prone to let the technical issues of rhinoplasties be externally visible with great ease and therefore aggravating their irregularities.
As prevention or once the irregularities have been produced it might be indicated adding on their top and beneath the skin camouflage layers like perichondrium or temporalis fascia grafting.
Step off deformity require revision to redo the osteotomies with better planning and skills.