1. Introduction

The LeFort I osteotomy is designed to separate the tooth bearing maxillary component from the superior part of the maxilla. The segment always contains the bony palate.

The mobilized segment can be moved in every direction. The procedure is a very versatile tool to correct maxillary deformities.

If changes in vertical maxillary height are intended, it is of crucial importance to use a fixed skeletal marker (K-wire or screw) which will allow vertical measurements before and after the osteotomy is anchored into the nasofrontal junction.

AO Teaching video on advancement and fixation of the Maxilla and Mandiblehttps://cdnapisec.kaltura.com/html5/html5lib/v2.78.2/mwEmbedFrame.php/p/2396982/uiconf_id/44564041/entry_id/1_k3mbqe0k?wid=_2396982&iframeembed=true&playerId=kaltura_player2&entry_id=1_k3mbqe0k&flashvars[streamerType]=auto&flashvars[localizationCode]=en&flashvars[leadWithHTML5]=true&flashvars[sideBarContainer.plugin]=true&flashvars[sideBarContainer.position]=left&flashvars[sideBarContainer.clickToClose]=true&flashvars[chapters.plugin]=true&flashvars[chapters.layout]=vertical&flashvars[chapters.thumbnailRotator]=false&flashvars[streamSelector.plugin]=true&flashvars[EmbedPlayer.SpinnerTarget]=videoHolder&flashvars[dualScreen.plugin]=true&&wid=0_inxn63wz

2. Planning

For a detailed description of how to plan orthognathic surgery, please click here.

3. Approach

For this procedure the buccal sulcus approach is used.

4. Osteotomy

A periosteal elevator is inserted between the nasal mucosa and the lateral wall of the nose on one side. A curved retractor is inserted behind the maxillary tuberosity. A further instrument is used to retract upwards the lip and mucoperiosteal flap, exposing the lateral maxilla.

Horizontal osteotomies

The horizontal osteotomy is usually made at the level of the nasal floor at a safe distance (~5 mm) from the apices of the teeth.

When indicated, additional vertical interdental osteotomies to segment the dental arch are now performed. The osteotomies are completed after the downfracture.

The segments should be designed to ensure adequate blood supply to the individual osteotomized segments.

Posterior and vertical osteotomies

A curved pterygoid chisel is placed with the curvature pointing medially and inferiorly between the tuberosity and the pterygoid plates.

A mallet is used to drive the osteotome medially to complete the pterygomaxillary dysjunction. The position of the tip of the osteotome can be checked with a palpating finger.

Pitfall: An upward and posteriorly oriented osteotome will not reliably separate the maxilla from the pterygoid plates. It is also associated with increased risk of bleeding from the pterygoid plexus and internal maxillary artery.

Separation of the nasal septum from the palate

The nasal septum has to be separated from the palate with either an osteotome or septum scissors.

Special “guarded” osteotomes are used for this purpose to protect the nasal mucosa.

Separation of the lateral nasal walls

The lateral nasal wall is then separated using a nasal osteotome or saw.

Special “guarded” osteotomes are used for this purpose to protect the nasal mucosa.

Pitfall: This osteotomy should end anteriorly to the greater palatine vessels and nerve to prevent bleeding.

5. Downfracture and mobilization

Downfracture

The maxilla is downfractured anteriorly, with the help of a bone hook…

…or manually.

The downfracture maneuver allows for a complete visualization of the osteotomy lines. Remaining bony bridges at the posterior aspect of the maxilla can be transected under direct vision. To minimize bleeding when trimming bone close to the posterior maxilla, meticulous soft tissue protection should be employed.

The downfracture technique allows good access to the nasal septum for septal corrections when indicated.

It may be useful to use Tessier mobilizers (see illustration) or curved osteotomes which are inserted behind the maxilla on each side in order to pull the maxilla forwards. Rowe disimpaction forceps can also be used for this purpose.

At this point the mobilized maxilla should be free and able to be moved by the surgeon’s hand more than is actually required.

Anterior movements can be facilitated with traction using a wire directly attached to the maxilla or to a bone screw in the maxilla.

The interdental osteotomies and any additional palatal osteotomies to correct transverse discrepancies are now completed.

Care should be taken to preserve adequate blood supply to the individual osteotomized segments.

Positioning of the maxilla

Mandibulo-maxillary fixation is performed to position the maxilla to the desired relationship with the mandible. A prefabricated surgical splint (or wafer) may be used to facilitate this.

The maxillomandibular complex is now rotated around the condylar hinge until the desired vertical dimension has been attained.

Control of vertical height

The preplanned vertical position of the maxilla is then established against the fixed reference marker in the nasofrontal junction. When necessary, maxillary bone is removed with a drill until that vertical relationship is achieved passively. If the nasal septum or the inferior turbinates are preventing upward movement of the maxilla, they are reduced at this stage.

Posterior movement (backward)

Posterior movements are rarely indicated. If needed, a segment of bone must be removed usually from the posterior aspect of the maxilla. This is usually performed under direct vision from a downfracture approach.

Superior (upward) movement

Superior movement (shortening) of the maxilla requires an ostectomy of a bone segment.

In an upward movement of the maxilla the septum needs to be vertically trimmed to avoid septal buckling deviation, which may lead to impaired airway flow and nasal deformation. In large impactions, the inferior turbinates should be trimmed to avoid airway obstruction.

Inferior (downward) movement

Inferior movement (lengthening) of the maxilla is possible, but results in a gap and a non-contact situation between the upper and lower part of the maxilla.

The gaps need to be bone grafted, usually with free bone grafts from the iliac crest or the outer table of the skull, or allogeneic bone.

The amount of lengthening is checked against the vertical reference mark at the naso-frontal junction.

Asymmetric movement/rotations

Asymmetric movements and rotations are also possible. In this case a bone gap may occur on one side and bone may need to be trimmed on the contralateral side.

6. Fixation

Internal fixation

Internal fixation is performed with four miniplates, usually L- or reversed L-shaped, along the pyriform aperture and the zygomaticomaxillary buttress.

Care must be taken to passively adapt the plates to the bone surfaces. The screws in the mobilized maxillary segment must avoid the tooth roots.

After osteosynthesis, the need for bone grafts (eg. by rotational movements) should be evaluated and if required, they should be placed at this time.

Control of position

After completion of osteosynthesis on both sides, the MMF is released and the resulting occlusion is checked against the pre-planned position. The splint may be fixed to the maxillary teeth with a few thin wires (especially when the maxilla is segmented) and left in place during the healing phase to allow for neuromuscular adaption and position control.

Removal of glabellar reference screw

The glabellar reference screw is removed.

Special considerations

Pearl: Extensive anterior movements of the maxilla will stretch the soft tissue envelope of the face and will lead to bilateral widening of the alar base and the nasal vestibules. This can be prevented by performing an alar cinch suture, which engages both alar bases in an attempt to approximate them towards the midline immediately before wound closure.

7. Aftercare following orthognatic surgery with occlusal change

If MMF screws or Temporary Anchoring Devices (TADs) are used intraoperatively, they are removed at the end of surgery if not further needed for elastic traction. If a final splint was used, it may be fixed to the orthodontic devices (brackets) of the upper jaw to assure the planned occlusion and to serve as guidance for the neuromuscular adaption during functional training for about 2 weeks postoperatively.

To reduce swelling, the application of ice-packs or cooling devices during the early post-operative phase is advice. Intravenous steroids should also be continued for a short period postoperatively for the same purpose.

Antibiotic prophylaxis is continued for 1-5 days depending on the nature, complexity, and duration of the surgical procedure.

Especially in two-jaw surgery, the airway control is of major importance. An individual decision has to be taken if the patient can be extubated or should remain intubated until it is clear that safe airway can be established.

Early post-operative x-rays are obtained to verify correct segment position. Additional postoperative imaging is performed as needed.

Regular follow up examinations to monitor healing and the postoperative occlusion are required. If an occlusal problem is present in the early postoperative phase, the surgeon must determine its etiology. If the malocclusion is secondary to surgical edema or muscle detachment/disorders, training elastics may be beneficial. The elastics are only used for guidance, because active motion of the mandible is desirable. Patients should be instructed how to place and remove the elastics using a hand mirror. If the malocclusion is secondary to a bone problem due to inadequate fragment positioning, displaced or failed hardware, or condylar displacement during surgery, elastic training will be of no benefit. The patient must be rescheduled for revision surgery.

At each appointment, the surgeon must evaluate the patient’s ability to perform adequate oral hygiene and wound care and should provide additional instructions if necessary.

Postoperatively, patients will have to follow three basic instructions:

1. Diet
In orthognathic surgery the internal fixation devices usually do not allow for full functional load. A soft diet should be used up to 6 weeks, starting with liquids for the first 3-4 days. Elastics can be removed during eating.

2. Oral hygiene
Patients with intraoral wounds must be instructed in appropriate oral hygiene procedures. The presence of orthodontic appliances, the splint, and elastics makes this a more difficult task. A small soft toothbrush with toothpaste should be used.Any elastics are usually removed for oral hygiene procedures. Additionally, antiseptic rinses can be used in the early postoperative period. An oral irrigator (eg, Waterpik) is a very useful tool to help . If a Waterpik is used, care should be taken not to direct the jet stream directly over intraoral incisions to prevent wound dehiscence in the early postoperative phase.

3. Functional training/physiotherapy
The patient is instructed how to perform functional training (opening and excursive exercises) as soon as possible. The progress should be monitored by the surgeon. If available and needed, a physiotherapist can support the functional rehabilitation. An undisturbed mouth opening of minimum 35 mm interincisal jaw opening should be attained by 4 weeks postoperatively.

In case of undisturbed healing, the postoperative orthodontic treatment can usually start 2 to 6 weeks after surgery depending on the case.