Le Fort II Advancement With Distraction Osteogenesis
Eugenia K. Page
Colin M. Brady
Joseph K. Williams
DEFINITION
A Le Fort type II is a pyramidal fracture pattern that peaks at the nasofrontal suture and extends across the orbital floor and rim, underneath the zygoma, and then wraps around the pterygomaxillary fissure through the pterygoid plates. This was first described in 1901 by the French military surgeon Rene Le Fort.1
Variations of the Le Fort II osteotomy, including the anterior, pyramidal, and quadrangular types, have been utilized to advance the hypoplastic midface (FIG 1).
The various osteotomy patterns can be utilized with distraction osteogenesis (DO) to achieve changes in the midface skeleton including nasal projection and maxillary advancement.
ANATOMY
Identify the lacrimal system (ie, inferior lacrimal duct and sac) and the medial canthal attachment in the superior/posterior aspect of the medial orbit, located on the maxillary process of the frontal bone (FIG 2).
PATIENT HISTORY AND PHYSICAL FINDINGS
Nasomaxillary deficiency is commonly found in craniofacial syndromes such as Crouzon, Apert, and Pfeiffer syndromes but can also be due to craniosynostosis, hemifacial microsomia, Romberg disease, Binder syndrome, traumatic defects, and cleft and non-cleft-related nasomaxillary hypoplasia.2,3,4,5
FIG 1 • Comparison of Le Fort II osteotomy patterns. Blue, anterior; green, pyramidal; red, quadrangular.
Presurgical assessment should include airway, speech, occlusion, mastication, and social/psychological consequences of the craniofacial deformity.
Physical findings include maxillary hypoplasia with an associated class III molar relationship and varying degrees of recession of the nasal base as well as malar deficiency.6
Exophthalmos is traditionally corrected with a Le Fort III advancement; however, successful repair has been reported using a Le Fort II osteotomy that includes the majority of the inferior orbital rim.7
Nasomaxillary retrusion is the most common finding in patients who need a Le Fort II procedure in which a pyramidal Le Fort II pattern is used (TABLE 1).
IMAGING
Cephalometric analysis of the facial skeleton may be used to characterize and quantitate the areas of deficiency.
Overlay grids taken from age-matched norms of facial skeletons may highlight deficiencies and can be used to determine the amount of skeletal movement.
Dental radiographs and orthodontic records are obtained for orthodontic preparation and timing of the procedure (mixed vs adult dentition).
Computed tomography with three-dimensional (3D) reconstructions should be obtained.
Virtual surgical planning (VSP) uses CT images to improve accuracy of the osteotomies and decrease operative time. VSP is advantageous for planning vectors, advancement distances, manufacturing skull models and occlusal splints, molding distraction devices preoperatively, and avoiding potential periorbital asymmetries.8,9
Skull models are constructed from the scans via either stereolithographs or 3D modeling for presurgical planning and device fitting in the operating room.
A polysomnogram may be needed to evaluate airway obstruction secondary to the midface retrusion.
SURGICAL MANAGEMENT
In patients in whom the advancement required at the midface level is no more than 6 to 8 mm, mobilization of the mild hypoplastic midface can be performed with definitive advancement, bone grafting, and plate fixation.
In syndromic patients, those with moderate to severe midface hypoplasia with significant negative overjet/class III malocclusal patterns, and adolescents still in active facial development, use of techniques for midface level DO is recommended.10
 FIG 2 • Relevant skeletal anatomy. A. Sagittal view. B. Coronal view. C. Skull base view. |
Table 1 Indications for Using Le Fort Osteotomies | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Preoperative Planning
Two commercially available external halo devices are available (External Midface Distractor, manufactured by Synthes, Oberdorf, Switzerland, and the Rigid External Distractor, manufactured by KLS Martin, Tuttlingen, Germany).
The primary advantage of the external device is the ability to perform real-time modification of the vectors of force during distraction and its versatility for distraction at all Le Fort osteotomy patterns.
Secondary benefits of the external device include the technical ease of device application and removal, as well as a decreased risk of unfavorable fracture patterns in areas of thin cortical bony stock during pin application.
Disadvantages of the halo are patient noncompliance related to the psychosocial stigma of wearing the device, as well as frame- and hardware-related complications such as pin loosening and pin-site scarring.11
An internal maxillary device can also be used for both quadrangular and pyramidal patterns.
Despite improved compliance, these designs are criticized because they distract at a single pivot point, with an inability to adjust the vector of force during distraction.
The consequent vector may result in a clockwise rotation of the entire midface during distraction, leading to long midface and an uncorrected or undercorrected class III malocclusion with a posterior open bite.
FIG 3 • Access incisions for Le Fort II level osteotomies. A. Maxillary vestibular incision. B. Bicoronal incision with deep temporal fat pad dissection. C. Transconjunctival approach with lateral canthal extension. D. Sagittal view demonstrating preseptal plane.
The potential for clockwise rotation of the midface during distraction at the Le Fort II level may be addressed by using temporary anchorage devices (TADs) or microimplants to hold interarch class III relationship elastics.Related posts:
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