Continuing Education Activity

The LeFort I osteotomy is utilized extensively within the field of oral and maxillofacial surgery when repositioning of the maxilla is required for correction of dentofacial abnormalities or to facilitate surgical access. The osteotomy allows both horizontal and vertical movement and, when performed as a segmental osteotomy allows for transverse expansion. This activity outlines and reviews the origins, indications, limitations/contraindications, potential complications, and clinical significance for the LeFort I osteotomy and highlights the role of the interprofessional team in evaluating and treating patients with dentofacial abnormalities.

Objectives:

• Identify pertinent anatomical structures associated with the LeFort I osteotomy.
• Review the indications for the LeFort I osteotomy.
• Describe the surgical technique for the LeFort I osteotomy.

Introduction

The LeFort I osteotomy is a horizontal maxillary osteotomy utilized in the correction of midface deformities allowing movement anteriorly/posteriorly, vertically, rotationally, and with segmentation: expansion. It can also be utilized to facilitate surgical access for the removal of tumors or the reduction of complex midfacial fractures. It is named in accordance with the LeFort I horizontal fracture pattern described by Rene LeFort in 1901.[1] 

The earliest maxillary osteotomies were utilized to facilitate exposure for removal of nasopharyngeal polyps, and the first LeFort I osteotomy for correction of dentofacial deformities was described by Wassmund in 1921 utilizing orthopedic traction rather than intra-operative mobilization. Auxhausen first described the osteotomy with intra-operative mobilization in 1934 for the closure of an open bite. Schuchardt separated the pterygomaxillary junction allowing anterior repositioning. Bell’s research demonstrated the revascularization phenomenon, the ability to sacrifice the descending palatine arteries without compromising blood supply, and the ability for osseous healing from a complete maxillary osteotomy, thus providing the biologic basis for a complete down fracture. As the procedure has continued to evolve, incorporating and recognizing the roles of hypotensive anesthesia, orthodontics, tension-free stability, and virtual surgical planning, it has become widely accepted as a common, predictable, and safe procedure.[2][3]

Anatomy and Physiology

The maxilla is comprised of paired maxillary bones fused at the midline. It articulates with the frontal bone superiorly, the alveolar process inferiorly, bilateral zygomatic bones laterally, posteriorly with the palatine bone, and posterolaterally with the pterygoid plates of the sphenoid bone.[4]

Blood supply to the LeFort I segment is provided by the ascending palatine artery, a branch of the facial artery, and the anterior branch of the ascending pharyngeal artery, which arises directly from the external carotid artery.[2] During the LeFort I osteotomy potential for significant bleeding requires in-depth knowledge of the location of various blood vessels in relation to the procedure. In particular: the descending palatine arteries are located posterior to the pyramidal processes of the palatine bone and can be inadvertently damaged as a result of over-extension of the lateral nasal osteotomy. Inappropriately superior placement of the osteotome for separation of the pterygomaxillary junction can interrupt the pterygopalatine fossa and damage the internal maxillary artery and its branches.[5]

Innervation to the maxilla is via the maxillary division of the trigeminal nerve (V2), which originates in the trigeminal ganglion, exits through the foramen rotundum to enter the pterygopalatine fossa, where it gives off multiple branches. The infra-orbital nerve, a terminal extension of V2, exits through the infraorbital foramen and provides sensory innervation to the soft tissue of the midface: lower lid, cheek/malar region, nose, upper lip, and anterior maxillary dentition. The infraorbital nerve is encountered in the dissection for the LeFort I osteotomy and should be identified and protected.[4][2]

Indications

LeFort osteotomy is indicated in the following:

• Maxillomandibular deformities
  • Maxillary hypoplasia and/or mandibular hyperplasia
  • Vertical maxillary excess
  • Angle’s class II and class III malocclusions
  • Midline discrepancies/asymmetries
  • Apertognathia/open bite
  • Absolute transverse arch discrepancy*
  • Dual or multi-planar occlusion*
  • Severe maxillary atrophy (in conjunction with bone grafting)
• Obstructive sleep apnea
• Access for skull base tumors
• Facilitation of reduction of non-reducible fractures[2][3][6][7][8]

*Segmental or multi-piece LeFort osteotomy (not covered in this article)

Contraindications

Here are some complications of LeFort osteotomy:

• Incomplete skeletal growth/skeletal immaturity
• Severe and/or uncontrolled periodontal disease
• progressive dentofacial deformities (e.g. condylar hyperplasia, idiopathic condylar resorption)
• bone/joint diseases (e.g. osteoporosis, osteopenia)
• medical comorbidities (e.g. uncontrolled diabetes, immunocompromise)
• poor nutritional status (hypoalbuminemia)[9][10]

Contraindications should be considered relative in nature and in certain scenarios may conversely be an indication for the surgery. Thus the surgeon must perform a thorough pre-operative evaluation and ensure that informed consent is obtained from the patient, parent, or legal guardian regarding risks, benefits, and potential complications before proceeding with surgery.

Equipment

The following equipment is needed for LeFort osteotomy 

• 15 blade
• monopolar and/or bipolar electrocautery
• assorted retractors
• marking pen
• local anesthetic with epinephrine 
• Kirschner "K" wire
• gauge or caliper
• assorted periosteal elevators
• reciprocating saw
• straight tapered fissure bur (701 or 702)
• U-shaped or double guarded straight osteotome
• single guarded osteotome
• cruciform or large curved osteotome
• Turvey spreaders
• Rowe dis-impaction forceps
• Rongeur
• bone-eating bur or reciprocating rasp
• small single pronged skin hook 
• sutures
• assorted 24-28 gauge wires[2][11]

Personnel

The following personnel are needed:

• Surgeon(s)
• Surgical assistant
• Surgical technician
• Peri-operative nurse
• Anesthesiologist and/or nurse anesthetist 
• Post-anesthesia care unit nurse

Preparation

A comprehensive work up to include a detailed history and physical examination, facial analysis, and meticulous surgical planning via virtual surgical planning or traditional model surgery should be performed as part of the pre-operative workup. If applicable, orthodontics may be performed before surgery to level, align, and decompensate the dentition.

Technique or Treatment

The procedure is performed under general anesthesia in the supine position. Nasotracheal intubation facilitates an intra-operative assessment of occlusion and placement in maxilla-mandibular fixation. The endotracheal tube should be secured passively but securely. Landmarks are established pre-operatively to provide reference points, which can be referred to throughout surgery to confirm the intended movements of the maxilla. This can be accomplished utilizing a k-wire or marking pen at the nasion or nasofrontal junction. Preoperative measurements are recorded measuring from the wire to the level of the orthodontic brackets or another stable and reproducible landmark bilaterally. Local anesthetic containing epinephrine is injected along the anticipated surgical incision to assist with hemostasis and post-operative analgesia. A throat pack is placed.

Plastic lip and cheek retractors, “toe-out” Obwegeser, or similar retractors can be utilized to provide better surgical access to the maxillary vestibule.

Careful planning of the surgical incision is necessary to provide an adequate cuff of gingival tissue for soft tissue closure. A minimum of 5mm above the mucogingival junction should be maintained. The initial mucosal surgical incision is made from the first molar to the first molar utilizing either a #15 blade or electrocautery perpendicular to the maxilla. The incision is extended down to the bone, and the periosteum is scored to facilitate subperiosteal dissection. Subperiosteal dissection is then performed with a periosteal elevator medially to the piriform rims with care taken to dissect the nasal mucosa around the nasal aperture. A curved freer elevator or the blunt end of a Woodson elevator may assist with the dissection of the nasal mucosa. The nasal mucosal dissection then proceeds posteriorly to the palatine bone. The subperiosteal dissection proceeds superiorly to the infra-orbital nerves, which should be identified and protected. Laterally, the dissection extends to and around the lateral maxillary buttress. At this curvature, it is of particular importance to maintaining a subperiosteal plane as failure to do so may inadvertently expose the buccal fat pad which will compromise and interfere with surgical access. A curved freer elevator may be useful in completing this part of the dissection. The lateral dissection terminates at the pterygomaxillary junction. A ray-tec sponge or neuro-patties may be placed in the lateral subperiosteal pocket at this point to allow further blunt dissection and assist with hemostasis while the osteotomy is being performed on the opposite side. 

Once fully exposed, the planned osteotomy may be marked with a Bovie electrocautery, a bur, or another implement. The osteotomy should be apical to the roots of the teeth while terminating below the inferior turbinate. An instrument such as a Sayre elevator or freer may be inserted on the medial aspect of the nasal aperture to protect the previously dissected nasal mucosa while completing the osteotomy if desired.

The osteotomy is then initiated at the lateral maxillary buttress and extended through the piriform rim utilizing a reciprocating saw, straight tapered fissure bur, or bone scalpel under continuous irrigation. The osteotomy is then mirrored on the contralateral side. Care should be taken not to apply force to the cutting implement as the initial bone in the buttress is dense however once through the buttress the anterior maxillary sinus wall is very thin and excessive force can result in loss of control of the implement and iatrogenic damage to the sinus wall as well as potentially compromised areas for fixation. Once bilateral osteotomies are completed, the lateral maxillary buttress can then be “back cut” by re-inserting the cutting implement into the lateral portion of the osteotomy and passing it in a medial to lateral direction. Alternatively, small straight osteotomes can be utilized to recapitulate the cut at the lateral buttresses.

Lateral nasal osteotomies are then completed with a small straight chisel or Neivert-Anderson single guarded osteotomes with the curved end of the osteotome in contact with the floor. Note that the lateral nasal wall diverges from anterior to posterior thus the osteotome must be oriented in a similar manner to account for this. A hard stop will be encountered when the osteotome contacts the pyramidal process of the palatine bone. The nasal septum is then separated from the maxilla utilizing a thin u-shaped osteotome or a double-guarded v-shaped osteotome which is seated on either side of the septum with the curved end of the osteotome against the nasal floor. To avoid damage to the descending palatine arteries care should be taken to avoid extending this osteotomy more than 30mm in females and 35mm in males.[12]

Finally, the pterygomaxillary junction is separated utilizing a large curved osteotome or a Tessier cruciform osteotome which is directed in an anterior, inferior, and medial direction at the junction. A finger is placed intra-orally against the pterygoid hamulus to ensure that the osteotomy is completed at the appropriate level. Prior to the pterygomaxillary osteotomy, it is prudent to alert the anesthesia team that the surgical team is preparing to down-fracture the maxilla. Anesthesia may wish to maintain mean arterial pressure (MAP) around 60 to limit excessive bleeding if a hypotensive anesthetic is preferred. The potential for damage to the maxillary artery and its branches the descending palatine artery and the sphenopalatine artery can result in significant bleeding during this step if the osteotome is inappropriately positioned. For this reason, some authors advocate for the separation of the maxilla at the tuberosity or through achieving down-fracture with digital pressure alone and foregoing the use of an osteotome at the pterygomaxillary junction.[13]

Ultimately, it is up to the experience, skill, and clinical judgment of the surgeon to determine which method for separation of the maxilla is indicated. Some surgeons prefer to separate the pterygomaxillary junction prior to the completion of the nasal osteotomies in order to expedite visualization and access in the event of vessel damage and brisk bleeding. 

Digital pressure should be utilized to down-fracture the maxilla. Excessive force should not be required to down fracture the maxilla if all osteotomies were properly completed and are, in fact, discouraged as it can result in an unfavorable fracture and other complications. If the maxilla does not down fracture at this point: each previous osteotomy should be carefully checked and recapitulated if necessary until such a point that the maxilla down-fractures easily.

Once down-fractured, additional nasal mucosal dissection or repair of torn nasal mucosa will be more easily performed due to improved access. Repair is best performed with a fine, resorbable suture such as a 5-0 fast-absorbing gut.

Completion of the down-fracture should be followed by careful inspection for any active bleeding which needs to be controlled at this point prior to proceeding. Bleeding can be controlled with packing/pressure however pulsatile bleeds are best controlled with bipolar electrocautery or ligation of identifiable vessels. Dependent upon surgeon preference: the descending palatine arteries can be identified, exposed, maintained, or conversely ligated and sacrificed at this stage. The sacrifice of the descending palatine arteries will not result in a vascular compromise of the maxilla.

Dependent upon the planned surgery, the soft tissue may require stretching at this point to allow for mobilization and tension-free repositioning of the maxilla to the pre-determined post-operative position. This can be accomplished with digital pressure or Rowe dis-impaction forceps.[11] Care should be taken when placing and manipulating the maxilla with the forceps as damage to the teeth or the maxillary bone can occur if used improperly.

The pre-operative surgical plan and indications for the osteotomy will dictate the next steps in the procedure. A planned impaction, as in the case of vertical maxillary excess, will require bone reduction and reduction of the nasal septum to allow for appropriate repositioning and to prevent nasal septal deviation. Large advancements or down-grafts may require bone grafting for added stability and success; both autogenous and allograft sources are acceptable.

If a surgical splint has been fabricated it should be fitted to the dentition, the maxilla should be manipulated into position, and the patient should be placed into maxillomandibular fixation utilizing stainless steel wires. The entire maxillomandibular complex is rotated up, ensuring that the mandibular condyles are seated in their respective fossae. Failure to seat the condyles may result in post-operative malocclusion. At this point it is also appropriate to re-check the landmarks determined pre-operatively and the anticipated moves against the actual position of the maxilla to confirm appropriate positioning, making adjustments as needed. Fixation is then accomplished utilizing plates and screws. Plates are bent and adapted to the contours of the position of the maxilla and are secured to the piriform rims and the zygomaticomaxillary buttresses bilaterally, 4 plates in total. Alternatively, Lindorf style pre-bent plates can be utilized on each piriform rim, 2 plates in total.

The patient should then be released from maxillomandibular fixation and the mandible should be rotated in and out of the splint (if present) to confirm passive rotation in and out of centric occlusion. Centric relation should also be checked at this point. An occlusal discrepancy at this point is indicative of a potential failure to appropriately seat the condyles and will require consideration of removal and replacement of hardware. Dental and skeletal midlines should also be checked at this point to ensure that the pre-determined positions have been achieved.

The surgical site is then irrigated and the mucosa is closed in a watertight fashion utilizing a resorbable suture such as 3-0 or 4-0 chromic gut in a continuous or continuous interlocking fashion.

Prior to closure of the vestibular incision a nasal cinch or alar cinch suture may be considered to limit widening of the alar base as seen with large maxillary advancements. This is accomplished by everting the vestibular incision and passing a slowly resorbing or non-resorbable 2-0 to 3-0 suture through the transverse nasalis muscle on either side of the alar base intraorally. The suture is then cinched down in a controlled fashion and care is taken to ensure that the alar bases are narrowing symmetrically. Evaluation of this maneuver can be made more difficult by the presence of a nasal endotracheal tube which distorts this landmark.[14]

Consideration should be given to performing a V to Y closure if concern for excessive thinning or may be performed at this point to avoid excessive shortening and thinning of the lip. To perform a V to Y closure a single prong skin hook is placed in the labial mucosa at the midline and lifted approximately 1 cm. The same suture utilized for mucosal closure is then passed in a continuous fashion to create a 1 cm vertical limb. Vestibular closure then proceeds on either side.[14] The decision to perform either procedure should be based on the anticipated soft tissue changes associated with the planned surgery, surgeon experience, and preference. The oral cavity is suctioned free of debris, a nasogastric or orogastric tube may be passed at this point to suction the patient’s stomach contents, and the throat pack is removed. Guiding elastics or maxillomandibular fixation is then placed if indicated.

Complications

While a technically simple and versatile procedure, rare but serious complications can occur and the potential for complications must not be overlooked by the surgeon. Complication rates are variable and incidence has been reported in several studies between 6.7% TO 8.77%.[15][5] Complications can broadly be categorized as anatomic, septic, ischemic, vascular, neurologic, and otologic.[2] In a prospective study of 1000 patients, Kramer et al found that patients with major anatomic irregularities (i.e. craniofacial or cleft patients or patients with vascular abnormalities) were at increased risk of complications and accounted for a disproportionate number of those observed.[15] Patients who undergo segmental osteotomies or large advancements were also shown to have an increased risk of complications.[2][15] Another smaller study excluding segmental osteotomies and patients with major anatomic irregularities demonstrated an increase in complications associated with maxillary setbacks relative to other movements.[5]

The most commonly encountered complications are anatomic and include nasal septal deviation resulting from an inadequate reduction of the cartilaginous septum when performing a maxillary impaction, non-union of the osteotomy gap, improper positioning of the maxilla.[14][15][16] Common septic complications include abscesses and maxillary sinusitis both of which are readily controlled by conservative therapies.[15] The primary vascular complication of concern is hemorrhage which typically occurs as a result of damage to branches of the maxillary artery most often the result of an unfavorable fracture of the pterygoid plates.[15][17] This can be avoided by careful surgical technique and osteotome placement or consideration of alternatives to the traditional pterygomaxillary osteotomy. Tranexamic acid at 10mg/kg 30 minutes prior to induction of general anesthesia is also advocated to reduce blood loss.[18]

Ischemic complications to include avascular necrosis are associated with large advancements, segmental osteotomies, and major anatomic irregularities. If a large advancement is anticipated consideration should be given to two jaw surgery to limit large anterior/posterior movements in a single jaw.[15] 

Damage to teeth or root amputation is another complication that may be encountered but is related to surgeon experience and failure to initiate the osteotomy apical to the roots of the teeth. Neurosensory deficits in the infraorbital nerve are frequently seen after surgery secondary to compression or retraction but typically resolve with the majority of patients regaining full sensation at 2 months and all patients regaining sensation in 6 months.[5] Other more serious neurologic complications have been reported such as unilateral blindness and oculomotor nerve palsy however these complications are exceedingly rare.[2]

Clinical Significance

The relative safety, versatility, and technical simplicity of the LeFort I osteotomy contributes to its position as a workhorse in maxillofacial surgery. With numerous applications including but not limited to reconstruction, trauma, pathology, and sleep medicine: the LeFort I osteotomy has utility for surgeons of multiple disciplines.

Enhancing Healthcare Team Outcomes

While the LeFort I osteotomy is most commonly performed by oral and maxillofacial surgeons or other head and neck surgeons, the critical importance of an interdisciplinary team is pre-operatively, peri-operatively, intra-operatively, and post-operatively cannot be overlooked. Successful outcomes are contingent upon comprehensive multi-disciplinary care and support. Pre-operatively and post-operatively, the orthodontist plays a critical role in preparing the patient for orthognathic surgery and by providing input and expertise relative to the surgical treatment plan and the anticipated need for post-surgical orthodontics.

For patients with medical comorbidities, pre-operative optimization is essential to safe and successful surgery. Depending upon the patient’s medical conditions, pre-operative optimization may involve care coordination and planning by physicians and caregivers from multiple disciplines. Intra-operatively, the role of the anesthesiologist or anesthesia provider facilitates a safe surgery and emergence from general anesthesia. Coordination and discussion between the surgeon and the anesthesia provider with respect to desired intubation technique, risks versus benefits of hypotensive anesthesia and timing of hypotensive anesthesia, and planning ahead for potential airway issues posed by maxilla-mandibular fixation and postoperative edema. Hypotensive anesthesia has been shown to reduce blood loss and provider better visualization of the surgical field and shorten the length of hospital stay.[19][20]

In the immediate post-operative period, the nursing team will play a vital role in patient education, providing psychosocial support, and ensuring that patients meet immediate post-operative milestones. The pharmacist and pharmacy team will play an important role in determining the appropriate post-operative medications for the patient balancing adequate pain control with minimization of deleterious side effects. The pharmacist also plays a role in devising appropriate and effective pain control regimens for patients at risk for over narcotization or respiratory depression, as is the case with obstructive sleep apnea patients or the morbidly obese. Proper nutrition is critical for wound healing; thus, nutritionists and Registered Dieticians play a vital role in determining appropriate caloric needs, supporting and facilitating a dietary regimen, ultimately minimizing postoperative complications and decreasing patient morbidity.[21] [Level 5]