Osteotomy

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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, a safe distance (~5 mm) from the apices of the teeth.
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.
Sagittal osteotomy of the anterior alveolar crest and the palate


The sagittal osteotomy is usually made between the roots of the central incisors. To avoid iatrogenic damage of those roots it is recommended to first mark the position and penetrate the outer cortex with a small burr or with a piezoelectric device.


The osteotomy is continued posteriorly through the alveolus and the palate, usually with a thin straight scaled osteotome. Care must be taken not to penetrate the palatal mucosa. The course of the chisel tip as it goes posteriorly is monitored with a palpating finger, which is difficult with a tooth borne expansion device in place.
Check of segment mobility


After completion of the osteotomies, the mobility of the segments must be checked. The palatal expansion device can now be inserted, if not already in place.

Downfracture and mobilization of the maxilla

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Downfracture





The lower part of the maxilla is then mobilized initially by digitally pushing it downwards. The term downfracture was coined to describe this downward movement and the fracture of the posterior wall of the maxilla which has not been cut with either saws or chisels.


The remainder of the clefted nasal mucosa can now be visualized and sharply separated from the palatal mucosa to allow completion of the mobilization.


Pitfall: Incomplete osteotomies and excessive force during the downfracture are thought to have caused fracture of the posterior wall of the maxilla running up into the orbit and as a result causing blindness. Consequently excessive force during downfracture and incomplete osteotomies should be avoided.


If major resistance is encountered, the following action should be taken:
Re-examine all of the osteotomy cuts especially in the posterior pterygoid region
Ensure all of the cuts have been completed successfully and if not, complete them
At downfracture it is usually possible to visualize the maxillary sinuses through the cuts and across the sinus to see the posterior wall of the maxilla. The posterior wall can be gently osteotomized under that direct vision using a fine osteotome taking care not to cause major bleeding.





During downfracture it is possible to visualize both the lateral wall of the nose, the nasal septum and the posterior wall of the maxilla across the maxillary sinus. Where the bone cuts are incomplete it is possible to complete the maxillary osteotomy with fine osteotomes under direct vision.





It may be necessary to trim the lateral wall of the nose and the nasal septum with bone rongeurs.
Mobilization





Digital manipulation (twisting) of the down fractured maxilla is performed to continue the mobilization.





Once initial mobilization digitally has been accomplished, Rowe's maxillary disimpaction forceps or similar devices may be used and the mobilization of the maxilla is completed. This should only be performed after inserting a custom made cast steel palatal protection plate to avoid damaging the palate or accidently fracturing the maxilla.


The mobilization is carried out by downward circular movements and then twisting the maxilla on each side in turn. During this procedure it is necessary to ensure that the mucoperiosteal pedicle to the maxilla postero-laterally does not tear.





It is often necessary to break down posterior scar tissue in the region of the soft palate either digitally or very carefully with blunt end dissection scissors. If this is not done, that scar tissue will be a major factor for future relapse.





It is sometimes useful also to use Tessier mobilizers which are inserted behind the maxilla on each side in order to pull the maxilla forwards.


At this point the mobilized maxilla should be free and able to be advanced by the surgeon by his or her hand much more than is actually required.
Trimming of osteotomy lines





With the maxilla displaced downwards, bony interferences on the lateral nasal wall and the anterior and posterior wall of the maxilla are removed. This can be done initially with rongeurs but usually bone has to be removed with a drill whilst carefully protecting the soft tissues. The greater palatine vessels may need to be sacrificed if they interfere with complete mobilization of the maxilla.


In order to prevent unfavourable pressure on the nose (widening of the alar base etc.) the piriform rims are rounded off and the anterior nasal spine reduced.