Download - Monobloc and Facial Bipartition Osteotomies

Monobloc and facial bipartition osteotomies

Ramon L. Ruiz, DMD, MDa,b,c,d,*, Timothy A. Turvey, DDSa,c,Paul S. Tiwana, DDS, MDa

aDepartment of Oral and Maxillofacial Surgery, University of North Carolina at Chapel Hill, Brauer Hall,

CB# 7450, Chapel Hill, NC 27599-7450, USAbDepartment of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA

cChildren’s Hospital of North Carolina, Chapel Hill, NC 27599, USAdUniversity of North Carolina Craniofacial Center, Chapel Hill, NC 27599, USA

Maxillofacial surgery underwent a dramatic evolution as a direct result of the experience

gained by surgeons who managed the facial injuries seen during the trench warfare of World

War I [1]. The surgical techniques pioneered for the repair of injuries that involved the maxil-

lofacial structures often were applied to the craniofacial skeleton and subsequently providedthe foundation for newer procedures used in the reconstruction of congenital deformities. In

the strictest sense, craniofacial surgical procedures are defined as those in which a transcranial

approach is used for access to the upper facial skeleton. Despite this distinction, however, most

craniofacial procedures represent an extension of the original scientific principles and traditional

techniques of maxillofacial surgery.

Tessier was the first to describe an approach for the correction of the craniofacial anomalies

associated with Crouzon and Apert syndromes using a Le Fort III osteotomy, which included a

combined extracranial/transcranial approach, access via a coronal scalp flap, interpositionalbone grafts for stabilization at the osteotomy sites, and an external fixation device [2–4]. Sub-

sequent modifications [5–7] resulted in the development of the monobloc and facial bipartition

procedures. More recently, the work of Posnick provides the most comprehensive description of

the specific surgical techniques, additional technical refinements, and clinical examples of ideal

functional and esthetic results in the correction of total midface deficiency associated with con-

genital deformities [8–13]. In North America, Posnick’s numerous publications have established

the role of the monobloc and facial bipartition procedures as viable reconstructive maneuvers in

the craniofacial surgeon’s armamentarium.The purpose of this article is to provide the surgeon with an overview of the monobloc and

facial bipartition procedures. The operative steps are described, with attention given to the in-

dications for surgery and specific intraoperative, technical considerations.

Indications

The craniofacial dysostosis syndromes (Crouzon, Apert, Pfeiffer, Saethre-Chotzen, and Car-penter) are inherited forms of craniosynostosis in which there is also extensive involvement of

the sutures of the midfacial skeleton. In addition to the cranial vault dysmorphology that results

from craniosynostosis (usually bilateral coronal), affected patients exhibit a characteristic total

midface deficiency that involves the orbits and maxilla.

The surgical correction of the craniofacial anomalies of the craniofacial dysostosis syndromes

requires at least three carefully sequenced stages of reconstruction [14,15]. Initially, release of

the bilateral coronal synostosis with reshaping of the cranial vault is undertaken. The surgical

Atlas Oral Maxillofacial Surg Clin N Am 10 (2002) 131–148

* Corresponding author.

E-mail address: [email protected] (R.L. Ruiz).

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technique used is similar to that for patients with nonsyndromic bilateral coronal synostosis.

Bifrontal craniotomy is combined with frontoorbital advancement and cranial vault reshaping.

In the second stage of reconstruction, correction of the total midface deficiency is under-

taken. The goal of this operative procedure is to improve cranial vault morphology further, nor-malize intracranial volume, and address further the problem of inadequate orbital depth. The

authors prefer to carry out this stage of the reconstructive sequence at approximately age 5

to 7, because the brain and cranioorbital structures have reached 80% to 90% of their adult size

[16]. The operation can finalize the position of the orbits and shape of the forehead. Waiting

until the permanent maxillary first molars have erupted also decreases the likelihood of damag-

ing these teeth and the developing second molars during the total midfacial osteotomy. It is at

this stage in the reconstructive sequence of the craniofacial dysostosis syndromes that the mono-

bloc and facial bipartition procedures may be applied. The exact timing of this operation alsodepends on the patient’s medical condition, functional neurologic concerns, and ophthalmologic

situation. Patients with a marked degree of exorbitism are at risk for corneal injury, exposure

keratitis, and disorders of ocular motility.

Later in life, definitive orthognathic procedures are required to finalize the occlusion. The

goal of second-stage reconstruction is to improve the contour and position of the orbits and

forehead. Although the maxilla may be advanced into an ideal anteroposterior relationship with

the mandible at the time of the monobloc osteotomy, it is not always possible to finalize the

occlusion with this operation. It is predictable that in patients with craniofacial dysostosis therewill be continued normal mandibular growth combined with deficient maxillary development,

which results in a significant class III malocclusion. These patients require definitive orthognathic

surgery to finalize the position of the lower face and occlusion. The surgical-orthodontic treat-

ment is usually planned once growth of the maxilla andmandible is complete (14–18 years of age).

The most common application for the monobloc facial advancement procedure is in the final

reconstruction of the cranioorbital deformities associated with Crouzon syndrome. The mono-

bloc osteotomy allows for advancement of the orbits, nasal complex, and maxilla as one unit.

This procedure allows final repositioning of the orbits while addressing the total midface defi-ciency present in these patients. In cases in which the amount of forward movement required

is different for the orbits than it is for the maxilla, the procedure allows for differential move-

ments, which is accomplished by further osteotomizing and recontouring the frontoorbital ban-

deau after the midface has been advanced. In cases in which the position and contour of the

forehead and superior orbital rims are acceptable, a subcranial Le Fort III osteotomy may be

used instead of the monobloc procedure. The decision regarding what type of osteotomy is car-

ried out must be based on the specific skeletal dysmorphology and the anteroposterior position

and contour of the frontoorbital region.Although there are similarities, the facial abnormalities associated with Apert syndrome

generally are more pronounced and have less variation than those associated with Crouzon syn-

drome. Patients with Apert syndrome also demonstrate downslanting palpebral fissures and

an increased facial width with orbital hypertelorism. In patients with Apert syndrome, second-

stage reconstruction is carried out using a facial bipartition procedure combined with repeat

cranial vault reshaping during childhood. Facial bipartition allows the surgeon to finalize the

orbital contours and position, correct the orbital hypertelorism, and advance the middle face.

The midline split and excision of a central fragment of bone permits forward rotation of the lat-eral orbits and the elimination of the ‘‘flat face’’ appearance characteristic of Apert syndrome

[8]. In these patients there may be an abnormally large frontal sinus, which must be managed

along with the extradural dead space at the time of surgery. The standard approach involves

cranialization, meticulous removal of the mucosal lining, and obliteration with autogenous

material (pericranial flap, free fat graft, bone graft).

The facial bipartition procedure also has found application in the reconstruction of the facial

deformity associatedwith craniofrontonasal dysplasia andatypicalmidline cleft anomalies. In cra-

niofrontonasal and frontonasal dysplasia, the typical skeletal dysmorphology is characterizedby widening of the upper craniofacial segment and orbital hypertelorism (see Fig. 1). In general,

the disproportionate skeletal growth is nonprogressive, and reconstruction of the midfacial

skeleton should be delayed until the cranioorbital units are near skeletal maturity (5–7 years

of age).

132 R.L. Ruiz et al. / Atlas Oral Maxillofacial Surg Clin N Am 10 (2002) 131–148

Fig. 1. (A) Preoperative view of a 6-year-old child with craniofrontonasal dysplasia. She underwent primary

cranioorbtial decompression and release of bilateral coronal synostosis during infancy and returned for second-stage

midfacial surgery. Surgical reconstruction consisted of a facial bipartition procedure with additional reshaping of the

anterior cranial vault. (B) Severe orbital hypertelorism and widening of the upper craniofacial skeleton are noted.

(C) Stereolithographic model of the same patient with proposed osteotomy sites. (D) Intraoperative view after exposure

through a coronal flap, osteotomies, and disimpaction with complete mobilization of the midface. The area of midline

ostectomy has been measured and marked. (E) Fragment of frontonasal bone excised measuring 27 mm.

(F) Repositioned facial halves with initial fixation. The interface is then recontoured using a surgical handpiece.

(G) Intraoperative view after fixation of repositioned frontal bones and the use of calcium phosphate cement for anterior

cranial vault reshaping. (H) Postoperative frontal view 1 year after surgery.

133R.L. Ruiz et al. / Atlas Oral Maxillofacial Surg Clin N Am 10 (2002) 131–148

Technique

Coronal flap

The coronal scalp incision is a versatile and cosmetically acceptable approach for accessto the cranial vault, cranial base, forehead, nose, upper middle face, and orbits. With the use

of this approach, inferior eyelid or transconjunctival access to the orbit in most cases is not

necessary.

Fig. 1 (continued )


The incision is placed from one supraauricular area to the other, and the degree of skeletalexposure required for a given procedure dictates the inferior extent of the incisions. When access

to the zygoma and infraorbital rims is necessary, the incisions must be extended further infer-

iorly. The hairline of the patient is a consideration in the placement of the incision. Although

anterior extension at the midportion of the coronal flap may enhance flap retraction and access

to the midface, the resulting scar subsequently may become obvious with male pattern baldness.

The authors’ preference is to place the incision across the top of the head rather than carry it

toward the forehead. The use of a postauricular coronal incision eliminates visible scars in

Fig. 1 (continued )


the preauricular area and decreases the risk to the frontal branch of the facial nerve in reoper-ated patients. Placement of this incision further posteriorly in the scalp is also beneficial in

children, in whom migration of the coronal scar may occur with growth. When secondary op-

erations are performed, it is preferable to reincise through the original scar. Although it may be

tempting to place the incision in a different location, consideration must be given to the effect of

the previous scar on flap perfusion and wound healing. Use of a curved or sinusoidal (stealth)

incision avoids a straight line scar and is particularly useful in patients with short hair.

Initially, the proposed incision is injected with a diluted solution of 1% lidocaine with

1:200,000 epinephrine. This solution reduces bleeding and helps dissection along the subapo-neurotic plane. Sterile saline may be injected freely into the subgaleal plane from the incision

line to the forehead with the use of a spinal needle. The scalp has a rich vascular supply, so

the incision is carried out in segments with the application of hemoclips. The authors’ preference

is to begin with the bilateral supraauricular portions of the incision. Once the initial incision has

been carried through the skin, two double-prong skin hooks are used to retract the wound edges

outward. Blunt dissection with a surgical sponge or finger is then used through the loose sub-

cutaneous connective tissue over each temporal extension to reach the temporalis fascia. Once

the proper layer has been established, the superior portion of the coronal flap incision (superiortemporal ridge to superior temporal ridge) is made. Bipolar electrocautery is used to obtain

hemostasis, which has a minimal effect on the adjacent peripheral hair follicles.

Once the pericranium is identified, a plane of dissection is established above it. Dissection

proceeds rapidly and bloodlessly to the forehead in this supraperiosteal plane.

Fig. 1 (continued )


Once the anterior cranial vault is reached, the dissection is converted to the subperiosteal

plane. An incision is carried through periosteum approximately 2 to 4 cm posterior to the super-

ior orbital rims. It is critical to remain within the subperiosteal plane during dissection over the

facial skeleton to avoid injury to the facial nerve. Bleeding from vessels that perforate the cra-

nium can be controlled with bone wax.When monobloc facial advancement is undertaken, the authors prefer a modification in this

technique that allows for the elevation of a large pericranial flap. A standard postauricular skin

incision is made and dissection is started forward in the supragaleal plane. The posterior edge of

the skin flap is undermined and the monopolar electrocautery is used to incise through the peri-

osteum 1 to 2 cm behind the incision line. The pericranium is raised as an intact flap. The right

and left margins of the flap are created along the superior temporal ridges and its anterior base is

meticulously preserved to maintain an adequate blood supply. Subperiosteal dissection con-

tinues forward to expose the frontal bone and orbitozygomatic structures. Once the flaps (cor-onal and pericranial) have been raised and they remain pedicled anteriorly, the pericranium is

wrapped with a surgical sponge soaked with antibiotic-containing solution. This solution pro-

tects the pericranium and prevents desiccation.

In infants and young children, care must be exercised when dissecting over open sutures,

especially midline sutures, to avoid venous sinus hemorrhage or injury to the meninges. In older

children who have undergone previous cranial vault surgery, full-thickness cranial defects may

remain and make dissection and elevation of the coronal flap more complicated. Care also must

be exercised when establishing a plane of dissection over the temporalis muscle. The naturalplane of dissection is subgaleal. Within the region over the temporalis muscle, the plane should

be deepened to the level of the muscle fascia (superficial layer of the deep temporal fascia). The

temporoparietal fascia, which is superficial to the fascia of the temporalis muscle and is an ex-

tension of the superficial musculoaponeurotic system, invests the temporal branch of the facial

nerve. Deepening the incision to the level of the temporalis muscle fascia avoids the nerve and

leads to subperiosteal dissection of the facial skeleton. The supraorbital nerves sometimes re-

strict flap mobility and dissection of the periorbita. Removal of the bony floor of the foramina

using a small osteotome is often required to release the supraorbital neurovascular bundles andpermit further forward mobility of the flap.

Closure of the incision in layers, even after facial advancement that exceeds 15 mm, is usually

not a problem. Before the coronal flap is repositioned, care should be taken to resuspend the

lateral canthal tendons. The authors begin by using a small single-prong skin hook to grasp

the tendon and lateral canthal soft tissues. Lateral canthopexy is then carried out using a non-

resorbable suture material or fine stainless steel suture ligatures placed through the tendon and

around the zygoma. Alternatively, a drill hole is made through the lateral orbital rim and the

suture is attached. When a pericranial flap is not used, the pericranium may be closed using4-0 chromic gut sutures. The wound must be irrigated with copious normal saline solution be-

fore closure. Once the skin flap is repositioned, closure of the coronal scalp flap is accomplished

in layers beginning with interrupted 3-0 vicryl sutures, which are passed through the galea and

reapproximate the subcutaneous tissues. Cutaneous closure typically has been accomplished

using surgical staples that are maintained for 12 to 14 days. The authors have found the

use of absorbable suture materials (chromic gut, vicryl rapide) to be favorable in the closure

of coronal flaps. This is especially true in pediatric cases in which the use of a resorbable

material for closure obviates the need for staple or suture removal during the postoperativeperiod.

Oral incisions

The use of transoral approaches to the facial skeleton also provides wide exposure while con-

cealing scars, which is an important component of the facial bipartition procedure. Typically,

this procedure includes a small midline incision within the maxillary vestibule to create a seg-

mental (sagittal) osteotomy of the maxilla. Although pterygomaxillary disimpaction may be car-ried out transorally, as performed during a Le Fort I level osteotomy, this requires a larger

vestibular incision and area of dissection. The authors’ preference is to use an osteotome placed

from above through the coronal flap for separation of the pterygomaxillary junction.


The monobloc facial advancement procedure

As described previously, the craniofacial skeleton is exposed through a coronal scalp flap ap-

proach. Care must be taken to expose the nasal dorsum, internal aspect of the orbits, lateralorbital rims and lateral walls, and zygomatic arch (Fig. 2). After the soft tissue dissection, bi-

frontal craniotomy is carried out and the frontal bone flap is removed (Fig. 3). The combination

of intracranial and subcranial (anterior) approaches allows retraction and protection of the

brain and globes so that the procedure may be carried out safely under direct visualization.

A reciprocating saw is used to create a small osteotomy through the zygomatic arch (Fig. 4)

and then a series of bone cuts through the lateral orbital wall down to the level of the inferior

orbital fissure, temporal bone (Tenon extensions), and anterior cranial base (Figs. 5–8), [17].

When the osteotomy is near the temporal fossa, adequate dissection of the fossa below the sphe-noid wing affords protection to the temporal lobe during the osteotomy procedure. This is espe-

cially important in patients with Apert syndrome, in whom the temporal lobe tip may extend

forward into the lateral orbital rim area.

Extension of the osteotomy cuts through the medial orbital wall and orbital floor is then ac-

complished with the use of a small osteotome. Care must be taken to avoid the infraorbital neuro-

vascular bundle and the nasolacrimal apparatus.

Separation of the nasal septal complex from the base of the skull is performed using a large

osteotome directed transcranially from the anterior skull base (in front of the cribriform) to thelevel of the maxillary crest (Fig. 9). Typically, an oral endotracheal tube is used during the initial

portion of the operative procedure. Once the nasal septum is divided, the patient may be con-

verted over to a nasal endotracheal tube. In cases in which nasal intubation is used, meticulous

care must be taken to avoid damaging the endotracheal tube during this osteotomy.

Next, a long, curved osteotome is used to separate the maxilla from the pterygoid plates. This

is approached from above through the coronal flap and a finger is placed over the medial surface

Fig. 2. (A, B) Once the coronal flap is elevated, care is taken to expose the entire craniofacial complex so that the

osteotomies may be carried out under direct visualization. This includes exposure of the nasal dorsum, internal walls of the

orbits, and zygomatic arch in the subperiosteal plane. The temporalis muscle is elevated from the squamosal portion of the

temporal bone,which allows access to the lateral orbital walls and the creation of Tenon extensions. (From Posnick JC.

Craniofacial dysostosis syndromes: a staged reconstructive approach. In: Turvey TA, Vig KWL, Fonseca RJ, editors.

Facial clefts and craniosynostosis: principles and management. Philadelphia: W.B. Saunders; 1995; with permission.)


of the pterygomaxillary junction to confirm complete separation and appropriate placement of

the osteotome (Fig. 10).

Once the osteotomies are completed, the bone cuts should be tested with a thin osteotome to

identify areas of incomplete separation and prevent unintended fractures. Attempts to mobilize

facial bones after incomplete osteotomies may result in fracture disruption of the segments,inadequate advancement, and relapse. These problems most frequently occur during movements

at the Le Fort III or frontofacial (monobloc) levels. Inadequate separation of the posterior max-

illary walls and perpendicular portion of the palatine bone, which are impossible to visualize

completely, contributes to this problem and may result in disruption of the zygomatic portion

Fig. 3. Transcranial access is provided through bifrontal craniotomy. Initially, bur holes are placed at the margins of the

bone flap and on either side of the sagittal sinus, which allows for separation of the dura before the craniotome is used

and the bone flap is elevated by the neurosurgeon. The frontal/superior orbital rim unit and Tenon extensions are

outlined with a surgical marker before bur holes are placed. (From Posnick JC. Craniofacial dysostosis syndromes: a

staged reconstructive approach. In: Turvey TA, Vig KWL, Fonseca RJ, editors. Facial clefts and craniosynostosis:

principles and management. Philadelphia: W.B. Saunders; 1995; with permission.)

Fig. 4. Osteotomy through the midportion of the zygomatic arch is completed with a reciprocating saw. (From Posnick

JC. Craniofacial dysostosis syndromes: a staged reconstructive approach. In: Turvey TA, Vig KWL, Fonseca RJ,

editors. Facial clefts and craniosynostosis: principles and management. Philadelphia: W.B. Saunders; 1995; with

permission.)


of the orbit. The use of osteotomes and specially designed bone spreaders assists in the comple-

tion of pterygomaxillary separation and minimizes the risk of associated fractures (Figs. 8, 10,

and 11) [13]. When fractures do occur, complete mobilization still must be accomplished. Repair

of the involved segments by plate fixation is indicated; when this is appropriately performed it

seldom results in a problem.Mobilization of the total midfacial skeletal unit is carried out with Rowe disimpaction for-

ceps used to apply slow, controlled, downward force (Fig. 11). The authors’ preferred approach

is to use a prefabricated occlusal splint and arch bars with wire maxillomandibular fixation to

stabilize the monobloc segment initially. Once the midface has been mobilized with the desired

advancement achieved and the patient placed into maxillomandibular fixation, attention may be

directed to the application of rigid internal fixation.

Fig. 5. Orbital bone cuts begin by dividing the lateral orbital wall and continue inferiorly to the level of the inferior

orbital fissure. An assistant places a malleable retractor within the orbit and retracts the periorbita. The osteotomy is

completed under direct visualization. (From Posnick JC. Craniofacial dysostosis syndromes: a staged reconstructive

approach. In: Turvey TA, Vig KWL, Fonseca RJ, editors. Facial clefts and craniosynostosis: principles and

management. Philadelphia: W.B. Saunders; 1995; with permission.)

Fig. 6. Superiorly, the lateral orbital osteotomy is extended to join the inferior line of the Tenon extension. During this

part of the operative procedure, a retractor is placed into the temporal fossa for protection of the temporal lobe. (From

Posnick JC. Craniofacial dysostosis syndromes: a staged reconstructive approach. In: Turvey TA, Vig KWL, Fonseca

RJ, editors. Facial clefts and craniosynostosis: principles and management. Philadelphia: W.B. Saunders; 1995; with

permission.)


The large skeletal movements carried out duringmonobloc facial advancements require careful

stabilization for successful outcomes. Inadequate stabilization contributes to relapse and infec-

tion, and the use of rigid fixation minimizes these problems. The application of bone plates and

screws for internal fixation of the osteotomized segments is done beginning at the zygomatic ar-

ches and lateral Tenon extensions. The authors’ preference is to use resorbable internal fixation

Fig. 7. The frontal lobes are gently retracted for access to the anterior cranial base. Osteotomy through the orbital roofs

is carried out from above using the reciprocating saw, which is continued in front of the cribriform plate in the midline.

(From Posnick JC. Craniofacial dysostosis syndromes: a staged reconstructive approach. In: Turvey TA, Vig KWL,

Fonseca RJ, editors. Facial clefts and craniosynostosis: principles and management. Philadelphia: W.B. Saunders; 1995;

with permission.)

Fig. 8. A small osteotome is used to complete the osteotomies, which allows the surgeon to test potential areas where

there has been incomplete separation and prevents unintended fractures. This is especially critical at pterion where

complete division with the saw is difficult because of visualization. (From Posnick JC. Craniofacial dysostosis syndromes:

a staged reconstructive approach. In: Turvey TA, Vig KWL, Fonseca RJ, editors. Facial clefts and craniosynostosis:

principles and management. Philadelphia: W.B. Saunders; 1995; with permission.)


wherever possible. The recent evolution in resorbable (polylactic acid polymer) rigid fixation sys-

tems hasmade this an attractive option for stabilization of the craniomaxillofacial skeleton.When

there is any question that the resorbable fixation will withstand the soft tissue relapse forces

encountered during midfacial advancements, titanium hardware is used for internal fixation.

The use of fresh autogenous bone grafts to fill osteotomy gaps provides the most predictableresults during orbital and midfacial procedures. Bone grafts are placed into the osteotomy gaps

Fig. 9. A larger osteotome is then placed through the cranial fossa osteotomy in front of the cribriform and driven

inferiorly to the level of the maxillary crest. The nasal septum is separated from the skull base. (From Posnick JC.

Craniofacial dysostosis syndromes: a staged reconstructive approach. In: Turvey TA, Vig KWL, Fonseca RJ, editors.

Facial clefts and craniosynostosis: principles and management. Philadelphia: W.B. Saunders; 1995; with permission.)

Fig. 10. Division at the pterygomaxillary junction is accomplished using a longer curved osteotome placed from above

through the coronal flap. A finger is placed over the medial aspect of the pterygomaxillary junction to confirm placement

of the osteotome and complete separation of the maxilla. Once disimpaction has been carried out, Posnick spreaders are

used to mobilize the maxilla adequately. (From Posnick JC. Craniofacial dysostosis syndromes: a staged reconstructive




at the zygomatic arch, along the posterior margin of the advanced frontal bones, and to recon-

struct the orbital floors after a monobloc advancement. These grafts are useful in restoring ana-

tomic contours and contribute to the stability of the advanced segments. As a general rule,

full-thickness bony defects of the cranial vault should be grafted to ensure adequate regener-

ation and continuity. This is especially true in children older than 2 years of age, in whomfull-thickness skull defects of more than a few millimeters do not heal predictably. The use of

split-thickness cranial grafts is favored because of proximity to the surgical site, ease of access

through the same coronal flap, and quantities of bone available. The consistency of the bone

in the cranium (dense cortical) and its rich haversian network allow it to revascularize quickly

and resorb minimally. Calcium phosphate bone cements also may be used for the repair of full-

thickness defects and recontouring the cranial vault (Fig. 1G).

Modifications for facial bipartition

The facial bipartition procedure begins with the same surgical steps carried out during a

monobloc facial advancement, which are carried out up to and including the complete disimpac-tion and mobilization of the midface. Before the facial halves may be translocated medially, two

additional surgical maneuvers must be carried out. First, midline ostectomy is carried out and

a segment of bone from the central face (frontonasal bones) must be removed (Figs. 12 and 1).

The specific amount of bone removed varies depending on the individual patient’s deformity

and is predetermined based on presurgical anthropometric and CT-based measurements. Second,

the maxilla is segmentalized into two segments using a midline (sagittal) osteotomy (Fig. 13).

A nasal-septal osteotome is used to separate the cartilaginous and bony septum from the max-

illary crest. The maxilla is then divided in the sagittal plane using a small midline osteotomycreated with a bur and then an osteotome for completion.

In addition to midfacial advancement, the division of the facial skeleton into two halves

permits translocation of the orbits medially for the correction of hypertelorism and forward

movement of the lateral orbital rims to correct the arch of the facial form (Fig. 14). The extents

to which these movements may be carried out are limited primarily by the palatal soft tissues

(Fig. 15). As the facial halves are translocated medially, the most notable change below the level

of the orbits is a widening of the maxillary arch form. The forward advancement of the lateral

Fig. 11. Disimpaction of the total midfacial unit is performed using Rowe disimpaction forceps to apply controlled,

downward, and forward traction. (From Posnick JC. Craniofacial dysostosis syndromes: a staged reconstructive




orbital rims produces differential widening, which affects the posterior maxilla. In patients un-

dergoing facial bipartition who have preexisting constriction of the maxillary arch, as is seen in

the craniofacial dysostosis syndromes, the surgeon encounters substantial resistance during

these skeletal movements. This is especially the case in children with a history of cleft palate

repair, in whom palatal scarring results in even greater maxillary transverse collapse and softtissue immobility.

Fig. 12. Removal of a fragment of midline bone (frontal and nasal) during facial bipartition. It is often necessary to trim

away any residual portions of ethmoidal bone and cartilaginous nasal septum that may interfere with translocation of

the facial halves. Care must be taken to minimize tearing of the nasal mucosa. (From Posnick JC. Craniofacial dysostosis

syndromes: a staged reconstructive approach. In: Turvey TA, Vig KWL, Fonseca RJ, editors. Facial clefts and

craniosynostosis: principles and management. Philadelphia: W.B. Saunders; 1995; with permission.)

Fig. 13. Sagittal osteotomy of the maxilla as used in the bipartition procedure. (A) Small midline vestibular incision with

exposure of the piriform rim, nasal floor, and septum. (B) Nasal-septal osteotome used for separation of the septum

along the maxillary crest. (C and D) A straight osteotome is then used to complete the segmentalization, and small bone

spreaders confirm mobility of the two maxillary halves. (From Posnick JC. Craniofacial dysostosis syndromes: a staged

reconstructive approach. In: Turvey TA, Vig KWL, Fonseca RJ, editors. Facial clefts and craniosynostosis: principles

and management. Philadelphia: W.B. Saunders; 1995; with permission.)


Once the orbital medialization is complete, rigid internal fixation is applied across the mid-

line. The central region is fixated before any bone plates are applied to the lateral Tenon exten-

sions or zygomatic arches.

Management of dead space

The elimination of dead space during closure of the craniomaxillofacial region is critical for

sound surgical practice. Dead space that results from craniofacial procedures is resolved by

meticulous closure of tissues, placement of bone grafts, and obliteration with soft tissue flaps

or free fat.

Forward advancements of the craniofacial skeleton during monobloc and bipartition proce-

dures result in the creation of extradural, retrofrontal dead space and communication with the

nasal cavity [11]. Potential complications of residual dead space include delayed healing, cere-brospinal fluid leaks, and infection. The management of this space in the anterior cranium after

frontofacial advancement remains controversial. Expansion of the frontal bones and relatively

rapid filling of the residual intracranial space has been well demonstrated in infants and young

children. This observation supports the conservative management of dead space in younger pa-

tients. More gradual, and less complete, filling occurs in the adult, which may be particularly

troublesome when the space communicates directly with the nasal cavity. Sealing the nasal

cavity from the cranial fossa is accomplished with primary repair of the nasal mucosa.

Because this is not usually feasible, the authors prefer to use an anteriorly based pericranialflap inserted for coverage of the anterior cranial base. The use of fibrin glue in the recon-

Fig. 14. Skeletal movements before (A) and after (B) facial bipartition. Notice that medial translocation of the upper

facial halves to correct orbital hypertelorism also results in some degree of lateral movement involving the maxillary

segments.


struction of the anterior cranial floor also provides a temporary seal between the cavities and

allows for re-epithelialization of the nasal mucosa. When forehead procedures are performed

and the frontal sinuses are present, management of the dead space is achieved by cranialization,

complete removal of the mucosal lining, and obliteration of the nasofrontal ducts with bone

grafts or free fat.

The placement of bone grafts into bony defects is important for closure of dead space and

facilitates rapid healing. These bone grafts should be wedged or stabilized with screws to preventmigration. Defects within the temporal fossa after facial advancements also may be covered

nicely with advancement of the temporalis muscles. This procedure eliminates the dead space,

and the defect is confined to the hair-bearing area of the scalp.

A layered closure of the coronal incision is required for elimination of dead space and an op-

timal esthetic result. The lateral canthus is stripped during the exposure of the orbital rims, and

these structures must be resuspended. Sutures are passed through the canthus and secured to the

lateral orbital rim or temporalis muscle fascia. When the temporalis muscle is stripped from the

lateral temporal crest or fossa, it should be reattached to the lateral orbital wall and temporalridge to prevent bitemporal defects. Closure of the subcutaneous tissues and galea is accom-

plished as a separate layer.

Until the nasopharyngeal mucosa seals, communications with the nasal cavity allow air leaks

that may result in subcutaneous emphysema or a pneumocephalus. To prevent this type of air-

flow, postoperative endotracheal intubation may be extended or bilateral nasopharyngeal air-

ways placed for a 3- to 5-day period. Sinus precautions and restriction of nose blowing also

further limit reflux of air and fluid during the postoperative period.

Fig. 14 (continued)


References

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Fig. 15. (A) High arched palate and narrowed maxillary arch width are common findings in children with craniofacial

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the midline result in lateral expansion of the maxillary arch form. Resistance is encountered from palatal soft tissues at

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