The patient is positioned on the operating table supine with the head in a head holder.
For corrective bone surgery, the whole face including the lower part of the forehead and eye brows, the auricles and the superior part of the neck need to be visible, and not covered with drapes. The nasal anaesthetic tube is covered with sterile adhesive tape and the cranium covered with two sterile drapes as illustrated. The eyes are protected with a bland eye ointment and the lips are lubricated.
To achieve a good hemostatic effect, local anaesthesia with a vasoconstrictor is injected into the labio-buccal sulcus from the midline to the maxillary tuberosities and pterygomaxillary areas.
Hypotensive anaesthesia is routinely employed during all but the final stages of the surgery maintaining the systolic blood pressure around 80 mm Hg.
Many methods have been described for ensuring that vertical changes during orthognathic surgery especially Le Fort I osteotomy are accurate. In the authors experience a screw inserted into the glabella (the root of the bridge of the nose) provides a good vertical reference point.
The procedure starts with the insertion of a 12-14 mm long screw with a cruciform head into a 6-8 mm hole drilled into the glabella. The distance between the middle of the cruciform head and the arch wire is measured with a caliper and recorded. All vertical changes are then measured against this reference distance.
Pearl: Using the electrocautery, two vertical reference dots are made in the labial frenum area of the maxillary midline to ensure that the incision is replaced accurately during suturing.
For a Le Fort I osteotomy or SARPE the incision starts 5 mm anterior and 5 mm superior to the opening of the parotid duct and proceeds forwards and slightly downwards in the labio-buccal sulcus crossing the labial frenulum in the midline and proceeds upwards in the same manner on the contralateral side.
For supra-apical osteotomies preserving the nasal floor, the incision is made at the same level (upper sulcus approach), but with a length appropriate for the surgical procedure and not circumferential.
Alternatively vertical incisions combined with a subperiosteal tunneling can also be used.
The incision is made through the mucosa, submucosa, underlying facial muscles and periosteum. An electrocautery needle may be used to further reduce bleeding. Care should be taken with the electrocautery in the region of the nasal floor so as not to damage it and also on the bone if the tooth roots have perforated the buccal plate.
3. Subperiosteal dissections
Sharp periosteal elevators are used to strip the soft tissues in the subperiosteal plane to expose the anterior maxillary wall, pyriform rims and nasal apertures, and zygomatico-maxillary buttresses. The periosteal dissection is performed in a systematic fashion.
This clinical photograph shows the dissection.
This clinical photograph shows the exposure gained.
Anterior midline and posterior (pterygopalatine fissure)
The subperiosteal dissection continues behind the zygomaticomaxillary buttress into the region of the maxillary tuberosity and the pterygomaxillary fissure. The tip of the periosteal elevator is always kept in intimate contact with the bony surface.
Pitfall: A perforation of the periosteum and slippage into the soft tissues can either produce a herniation of the buccal fat pad obscuring the surgical field and/or bleeding from veins of the pterygoid plexus.
Once exposed, a small curved up flat retractor (eg, a curved up Obwegeser retractor) is inserted behind the maxilla.
The nasal mucosa should be elevated from the lateral wall and floor of the nose with a periosteal elevator The anterior nasal spine and the lower border of the cartilaginous septum are addressed by soft-tissue retraction if necessary with a forked retractor, and the perichondrium on top of the cartilaginous septal border is incised.
Wound closure begins with the insertion of a single suture in the midline using the previous markings placed at incision.
The rest of the incision is then subsequently closed.
In cases of significant maxillary advancements or if the patients lip is short, a V-Y closure may be considered.