Le Fort I Distraction Osteogenesis

DEFINITION

Maxillary hypoplasia poses both functional and aesthetic challenges.
- Compromised mastication, speech abnormalities, nasal and pharyngeal airway constriction, dental malocclusion, and abnormal facial proportions are common.¹
Maxillary hypoplasia is a common finding in patients with orofacial clefts.
- Soft tissue scarring of the palate, pharyngeal structures, and lip may be severe, creating significant difficulties with traditional maxillary advancement.¹
Distraction osteogenesis (DO) is a powerful alternative to traditional Le Fort I advancement in patients with severe maxillofacial abnormalities. DO allows for greater advancement (greater than 8 mm) while avoiding the need for rigid internal fixation or bone grafting.²^,³
Rigid external distraction (RED) allows rigid, multivector control over the distraction process, allowing for successful and predictable outcomes.
- The method outlined in this chapter focuses on Le Fort I DO using the RED system.²

ANATOMY

The maxilla is composed of two adjacent bones that play several roles: separating the oral and nasal cavities, housing of developing and mature dentition, supporting the soft tissue of the face, and providing a stable platform for mastication.
In patients with orofacial clefts, the hypoplastic maxilla may be deficient in all dimensions with thin or structurally weak bone. The mandible is typically normal in size and morphology.⁴
Severe maxillary hypoplasia can be defined as a negative overjet of 8 mm or greater.

PATIENT HISTORY AND PHYSICAL FINDINGS

Many patients requiring Le Fort I DO have a history of cleft lip and/or cleft palate.
In addition to a complete history and physical examination, complete dental and orthodontic examination should be done to establish a multidisciplinary treatment plan.
Common physical examination findings in patients with severe maxillary hypoplasia include a concave facial profile and class 3 relationship with a large negative overjet, often greater than 8 mm (FIG 1).
- Scarring of the gingival mucosa may be present if the patient has undergone correction of orofacial clefts.

FIG 1 • Profile photograph of a patient with severe maxillary hypoplasia.

IMAGING

Preoperative panoramic radiographs are routinely done to assess dental and osseous anatomy.
Cephalograms and photographs are used for preoperative planning and postoperative comparisons (FIG 2).
Computed tomography is not required but may provide further anatomic details in complex cases.
Virtual surgical planning is not necessary for Le Fort I DO.

SURGICAL MANAGEMENT

Criteria for Le Fort I DO include patients with severe maxillary hypoplasia (horizontal, vertical, and transverse vectors), patients requiring greater than 8 mm of horizontal
advancement, severe palatal or pharyngeal scarring, concave facial profile, and airway obstruction or sleep apnea with normal mandibular position and morphology.

FIG 2 • Preoperative cephalogram.
Surgery is delayed until dental and skeletal maturity, if possible, usually around age 16 to 18 years. Indications for earlier intervention are airway compromise, severe occlusal disease, or severe psychosocial issues.

Preoperative Planning

Preoperative orthodontics are placed to align and level the dental arches prior to distraction.
- These movements are planned with dental impressions, casts, and models.
If the maxilla and dental arches are severely hypoplastic, preoperative orthodontics are not used, and the alignment and occlusion are addressed after distraction is complete.
The dental impressions are sent to a dental lab for creation of a custom-made intraoral splint.
- The splint acts as the link between the Le Fort I segment and the distraction device and is applied a few days before the surgical procedure.
- The splint is then cemented to the first permanent or second primary maxillary molar (FIG 3).
Two large, removable traction hooks made of heavy rectangular wire are constructed and will be placed when the distraction phase is initiated, postoperatively.
- These are not present at the time of surgery to facilitate intraoral manipulation and airway management.

Positioning

Patients are positioned supine with the head supported by a Mayfield headrest.
- Both arms are padded and tucked at the patient’s side.
- The bed is placed in a slight reverse Trendelenburg position.

Oral intubation is achieved and secured in place with circumdental wiring.

FIG 3 • Intraoral splint design used during maxillary distraction. Anterior square tubes are used to insert removable traction hooks. The splint is usually anchored to the maxillary first molars and secured anteriorly to maxillomandibular fixation screws placed at the time of Le Fort I osteotomy.

Nasal intubation is not required as mandibulomaxillary fixation and occlusal analysis are not necessary during the operation.

Tarsorrhaphy sutures are placed centrally to protect the cornea, and a throat pack is placed.
A thorough maxillofacial prep including half-strength peroxide oral brushing, alcohol skin scrub, and betadine paint is completed.
Sterile drapes are applied leaving only the face exposed.
- Exposure of only the nose and mouth is possible as no intraoperative aesthetic analysis for advancement of the maxilla is necessary.

Approach

Access to the maxilla is achieved through an upper buccal sulcus incision.
Compared with traditional advancement, the transverse maxillary osteotomy may be performed much higher allowing for distraction of a larger portion of the midface.
- This is possible as preservation of adequate bone stock for internal skeletal fixation hardware is not necessary.

TECHNIQUES

▪ Le Fort I Osteotomy

Soft Tissue Release

Local anesthetic with epinephrine is injected at the site of the upper buccal sulcus incision to minimize bleeding and improve pain control.
Maxillomandibular fixation (MMF) screws are placed adjacent to each maxillary canine tooth root (TECH FIG 1A).
- A 25-gauge wire is used to attach the preoperatively applied dental splint to the MMF screws. This provides additional support to the splint during the distraction phase.
The maxilla is approached through an upper buccal sulcus incision extending between the first maxillary molars bilaterally (TECH FIG 1B).
- Care is taken to maintain a 3- to 5-mm cuff of buccal mucosa attached to the gingival mucosal to aid in an eventual watertight closure.
A no. 15 scalpel is used to incise through mucosa; dissection is then continued to bone with needle-tipped electrocautery (TECH FIG 1C).
- Once through the periosteum, initial elevation of the periosteal dissection can be done with electrocautery to aid in further subperiosteal elevation.
- A periosteal elevator is used to release the soft tissue from the maxilla.
- Dissection is carried out around the pyriform aperture to release the floor and lateral walls of nasal mucoperiosteum.
- Superiorly, exposure beyond the level of the planned transverse osteotomy is performed. Care should be taken to avoid damage to the infraorbital nerves.
- Posteriorly, dissection is carried around the maxillary tuberosity toward the junction of the pterygoid plates for later disjunction.

TECH FIG 1 • A. Intraoperative placement of bilateral maxillomandibular fixation screws to provide additional security of the splint to the maxilla. B. Intraoral incision in the upper buccal sulcus is made through the mucosa with a no. 15 scalpel. A small cuff of buccal mucosal is left attached to the gingiva to aid in a watertight closure. C. Needle-tip electrocautery is used for dissection through periosteum. Initial elevation of the periosteum with electrocautery will aid in further dissection with the periosteal elevator. Tension and countertension should be applied with the suction tip.

Only gold members can continue reading. Log In or Register to continue