Maxillary, Mandibular, and Chin Advancement: Treatment ... · sleep deprivation, alcoholism, insomnia, and narco-lepsy. Furthermore, OSAS does not develop in all snorers. However,

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J Oral Maxillofac Surg69:663-676, 2011

Maxillary, Mandibular, and ChinAdvancement: Treatment Planning Based onAirway Anatomy in Obstructive Sleep Apnea

Stephen Schendel, MD, DDS,* Nelson Powell, MD, DDS,†

and Richard Jacobson, DMD, MS‡

Surgical correction of obstructive sleep apnea (OSA) syndrome involves understanding a number ofparameters, of which the 3-dimensional airway anatomy is important. Visualization of the upper airwaybased on cone beam computed tomography scans and automated computer analysis is an aid inunderstanding normal and abnormal airway conditions and their response to surgery. The goal of surgicaltreatment of OSA syndrome is to enlarge the velo-oropharyngeal airway by anterior/lateral displacementof the soft tissues and musculature by maxillary, mandibular, and possibly, genioglossus advancement.Knowledge of the specific airway obstruction and characteristics based on 3-dimensional studies permitsa directed surgical treatment plan that can successfully address the area or areas of airway obstruction.The end occlusal result can be improved when orthodontic treatment is combined with the surgical plan.The individual with OSA, though, is more complicated than the usual orthognathic patient, and both themedical condition and treatment length need to be judiciously managed when OSA and associatedconditions are present. The perioperative management of the patient with OSA is more complex and themargin for error is reduced, and this needs to be taken into consideration and the care altered asindicated.© 2011 American Association of Oral and Maxillofacial Surgeons
J Oral Maxillofac Surg 69:663-676, 2011
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urgical correction of obstructive sleep apnea syn-rome (OSAS) involves understanding a number ofarameters, of which the 3-dimensional (3D) airwaynatomy is important. Recent advances in the visual-zation of the upper airway based on cone beamomputed tomography (CBCT) scans and automatedomputer analysis have been a great aid in under-tanding normal and abnormal airway conditions andheir response to surgery. Knowledge of the specificirway obstruction and its characteristics based onreoperative studies permits a precise surgical treat-ent plan directed at the areas of restriction.1 The

goal of surgical treatment of OSAS is to enlarge thevelo-oropharyngeal airway by anterior/lateral dis-

*Professor Emeritus of Surgery, Stanford University, Palo

Alto, CA.

†Adjunct Clinical Professor of Surgery, Stanford University, Palo

Alto, CA.

‡Clinical Instructor of Orthodontics, School of Dentistry, UCLA,

Los Angeles, CA.

Address correspondence and reprint requests to Dr Schendel:

Stanford University School of Medicine, 1900 University Ave, Suite

101, Palo Alto, CA 94304; e-mail: [email protected]

© 2011 American Association of Oral and Maxillofacial Surgeons

278-2391/11/6903-0010$36.00/0

oi:10.1016/j.joms.2010.11.010

663

placement of the soft tissues and musculature bymaxillary, mandibular, and possibly, genioglossus ad-vancement (Fig 1). Treatment may also include thecorrection of transverse problems with expansion aspart of the overall plan and other soft tissue proce-dures such as uvulopalatoplasty.2 Review of the liter-ature indicates that maxillary and mandibular ad-vancement (MMA) is 75% to 100% successful in thecorrection of OSAS.3-8 MMA may be performed as atand alone procedure or as part of a staged treat-ent, which yields the highest success rates.3,9 In the

literature the usual advancement of the maxilla is atleast 1 cm. Long-term cephalometric studies haveshown good skeletal stability after MMA advance-ment in these cases.6,7 However, anatomic airwaychanges with surgery have generally only beenstudied on lateral cephalometric radiographs,which are 2-dimensional (2D). Three-dimensionalairway analyses permit a more refined and directedapproach to correction of the airway in OSAS, yetthere is little in the literature regarding the use ofthis modality. This article will cover the indicationsfor and planning algorithm in the treatment of theanatomic airway in OSAS by MMA based on com-puterized 3D analyses as an integral part of theoverall treatment plan, which must also address
neuromuscular and medical factors.
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664 SURGICAL CORRECTION AND OSAS

To effectively develop a treatment plan, the sur-geon should have a clear understanding of both themedical and surgical management used in OSAS.10

The treatment of OSAS, or the relatively newer term“sleep-disordered breathing” (SDB), which includessnoring and upper airway resistance syndrome, pres-ently is accomplished by medical and/or surgical man-agement. Neither of these 2 modalities is always suc-cessful, but each has its place in the management ofthese conditions. Primary medical management ofOSAS via continuous positive airway pressure (CPAP)is the main treatment modality for airway col-lapse.11-14 The partially or totally obstructed upperirway in OSAS/upper airway resistance syndrome isrimarily an anatomic problem secondarily influ-nced by neuromuscular influences and, therefore, aurgical problem.

There are 3 defined general anatomic levels (nose,alate, and base of tongue) in the upper airway tovaluate. Each may be partially or totally blocked inatients with OSAS. The surgeon’s goal is to enlargehe airway by repositioning or removing the obstruc-ion at each respective level without creating a com-lication. It is more difficult to treat the more distal

evels of the airway from the nose to the larynx. Thiss due, in part, to the increasing amount of soft tissuencountered (nose vs tongue). Furthermore, theleep patient is far more difficult to treat than issually anticipated because the problem is frequentlyultifactorial and it is easy to overestimate the ability

FIGURE 1. MMA and genioglossus advancement schema.

chendel, Powell, and Jacobson. Surgical Correction and OSAS.Oral Maxillofac Surg 2011.

o control all the variables. A few examples are factors

uch as weight, age, gender, body mass index (inilograms per square meter), skeletal and soft tissuenatomy, excessive daytime sleepiness (EDS), and theatient’s subjective response. Therefore it is prudento have a broad approach to the treatment, where allevels found to be obstructed are addressed. Failure orncomplete treatment will result if these issues are notppreciated, because OSAS is known to involve dif-use upper airway collapse during sleep and, there-ore, seldom will treatment of a single site be curative.

There are 2 major rationales that should be wellnderstood in the surgical management of OSAS. Therst, “behavioral derangement,” is due to EDS. EDS ishe result of nocturnal arousals during sleep due toirway collapse and usually manifests as sleepinessnd/or fatigue to such a degree that the subject lacksigilance and does not function normally during theay. Symptoms may include snoring, apneas, morningeadaches, fatigue, sleepiness after lunch, memory

oss, irritability, poor work performance, altered fam-ly relationships, and in some cases alterations in li-ido. These symptoms may be minimal, where theatient denies sleepiness, or severe, to the point thathe subject falls asleep driving and may cause a cata-trophic accident.12 When this level of sleepiness is

experienced, concentration and vigilance are im-paired and may result in dangerous pathologic sleep-iness. Regardless of the number of these symptoms,there is not necessarily a direct correlation with theseverity as seen on the apnea-hypopnea index (AHI).

The second rationale is “pathophysiologic derange-ment,” which is, in part, cardiorespiratory in nature. Itis well known that at some level of OSAS severity,there is an increased risk for myocardial infarction,stroke, and sudden death.13 Three important well-nown physiologic processes are involved in OSAShat predispose to these risks: hypoxemia, negativentrathoracic pressure, and disequilibrium of the au-onomic nervous system.14-17

The indications for surgery are as follows:

● EDS● Respiratory disturbance index (RDI) of greater

than 20 episodes per hour of sleep (or in caseswhere the RDI is �20 associated with markedobjective EDS)

● Oxygen desaturation of less than 90%● Hypertension and/or arrhythmia● Negative esophageal pressures more negative

than negative 10-cm H2O● Anatomic abnormalities of the upper airway● Failure of medical management (one of the most

common rationales but not an acceptable metric
by itself)

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SCHENDEL, POWELL, AND JACOBSON 665

These indications are similar to those for medicalmanagement with CPAP, which is not curative andfrequently not tolerated.

Patient Evaluation

The patient’s history and complaints are generallyassociated with snoring and/or EDS (behavioral de-rangement) and rarely do they mention respiratory orcardiac pathology as their chief complaint. Thereforeit is imperative that a basic understanding of thismetric exist when one is evaluating such patients.This is especially true in light of the fact there aremultiple other causes for the behavioral derangementin EDS other than OSAS. Some examples are volitionalsleep deprivation, alcoholism, insomnia, and narco-lepsy. Furthermore, OSAS does not develop in allsnorers. However, as intermittent snoring turns tohabitual snoring, the airway progressively collapses,and as a rule of thumb, if the bed partner frequentlyleaves the bedroom, there is about an 80% chance thepatient will have some degree of OSAS.

Preoperative Evaluation

GENERAL WORKUP

A thorough medical and sleep history should betaken regardless of age, and it is recommended inadults that a subjective questionnaire such as theEpworth Sleepiness Scale be used.18 The EpworthSleepiness Scale assesses the propensity of sleep in 8situations. It is not perfect and does not always cor-relate with OSAS severity but does give some infor-mation regarding the patient’s waking sleepiness.

A clinical examination of the head and neck alongwith a 3D CBCT scan, followed by fiberoptic naso-pharyngoscopy and polysomnography (PSG), is rec-ommended. Careful evaluation of the following issuggested: nasal airway obstruction, the palatal regionto include the lateral pharyngeal walls, the size andcharacter of the tonsils (if present), oral soft tissues,malocclusion or other skeletal abnormities, andtongue and tongue base. The clinical examination isthen correlated with the radiographic study and fiber-optic nasopharyngoscopy, along with data from anobjective overnight PSG scan and the subjectivesymptoms of the patient.

The airway can be divided into 3 anatomic sectionsfor evaluation and thus treatment of SDB; 1) nose, 2)retropalatal, and 3) retroglossal (Fig 2). Airway ob-struction may occur in any 1 or more of these areassimultaneously; thus a thorough knowledge of theanatomy in each area and its influence on the airwayis necessary. The airway description in this chapterwill deal with the internal anatomy and supporting
structures.1 t
The nose prepares the air for the lower respiratorytract by warming and humidifying it. Any deformity ofthe internal nose will affect airflow, and thus thesurgeon and orthodontist should be concerned withnasal aerodynamics. The nares act as a funnel guidingthe airstream toward the 2 valve areas, which is gen-erally the narrowest area of the nose. Deformities orcollapse of the alar cartilages will cause airflow reduc-tion at the external nasal valve. The angle betweenthe caudal end of the upper lateral cartilages and theseptum is called the internal nasal valve. This angle isnormally between 10° and 15°. The total nasal area atthis point has been estimated at between 55 and 64mm2 and is normally the smallest part of the airway.

ny stricture or stenosis here can cause restrictedirflow or turbulence. Airflow symptoms at this levelan be evaluated by the Cottle test. While the patientreathes quietly, the cheek is retracted laterally, thuspening the nasal valves; if the Cottle test improveshe breathing, the result is considered positive andndicates a valve problem. Septal deviations also ob-truct the nose in addition to causing airflow turbu-ence and secondary problems such as dryness andleeding. The turbinates, of which the inferior is theost import with regard to airflow dynamics, are in a

onstant cycle. One side is congested whereas thether is decongested; however, the total nasal resis-

FIGURE 2. Lateral schema showing the 3 general areas of airwayobstruction that may occur alone or, more frequently, in any com-bination: 1, nasal area; 2, retropalatal area; and 3, retroglossalarea.

Schendel, Powell, and Jacobson. Surgical Correction and OSAS.J Oral Maxillofac Surg 2011.

ance remains relatively constant. The turbinates rap-


idly heat the air from 0°C to 36°C and humidify it.Enlarged inferior turbinates can obstruct the nose andgreatly reduce airflow, and thus surgical reductionmay be indicated. The overall width of the face andespecially the maxilla also influences the nasal cavity,as the floor of the nose is the hard palate. Maxillaryconstriction seen with cross-bite–type malocclusionsand low tongue positions will thus decrease the nasalwidth, negatively affecting the airflow.

Area 2 in Figure 2 is the retropalatal area. Thisconsists of the space behind the soft palate and ante-rior to the posterior wall of the pharynx. Airflowdynamics here are influenced by the position of themaxilla, soft palate, and adenotonsillar structures. Aretruded maxilla will decrease the available spacebehind the hard palate and thus the airway. This ismost clearly seen in cases of midfacial retrusion suchas Apert-Crouzon syndrome, and clefting but can alsobe found in ordinary maxillary retrusion. The lengthand thickness of the soft palate are also important,and either a very thick or long palate will causeobstruction. Airway problems can be seen after cleftpalate surgery, especially after pharyngeal flap orsphincter-type procedures. In the adult with chronicSDB and snoring, the palate thickens, elongates, anddescends, further compounding the airway problem.In adolescents, however, the most common conditionis lymphoid hyperplasia with enlargement of the ad-enoids and tonsils. This reduces the retropalatal air-way, causing obstructive sleep apnea (OSA), and isstated to be the cause of airway problems 60% of thetime in this group.

Area 3, is the retroglossal region, which is mostinfluenced by the position of the mandible and thetongue. Retrusion of the mandible carries the base ofthe tongue posteriorly, and with relaxation duringsleep, the tongue may drop further back, obstructingthe airway and leading to apneic or hypopneic spells.Posterior tongue position can also influence palatalposition causing secondary obstruction at the palatallevel also. Some idea of the tongue position can begained from a lateral cephalometric radiograph; how-ever, more complete visualization of the tongue andthe airway can be gained from 3D imaging as seen onCBCT examinations and nasopharyngoscopy. The sizeof the tonsils also contributes greatly to airway size atthis level, mainly in the transverse width.

POLYSOMNOGRAPHY

The PSG study is an essential part of the surgicalworkup and must be done before and after surgery;otherwise, the patient’s PSG parameters and the sur-geon’s personal success rate will not be appreciated.Some of the parameters to insist on from an attendedPSG study are as follows: name; age; body mass index;
total sleep time of at least 240 minutes for a valid
study16; sleep stages NREM and REM, as well as per-cent of sleep in each; apnea index (mean and maxi-mum duration in seconds); hypopnea index (meanand maximum duration in seconds); awake SaO2; low-est SaO2; stratifications of the percent of time SaO2

were below 90%, 80%, 70%, and so on; heart ratefluctuations (bradyarrhythmia/tachyarrhythmias); andperiodic leg movements. All of these parameters maybe reviewed in most any text on sleep medicine.14

The severity as an index is summarized as the respi-ratory disturbance index (RDI) or, more frequentlynow, the apnea hypopnea index (AHI). An AHI of 5 orless is considered normal for an adult. The surgeonshould be aware that the polysomnogram (PSG) studyshould be current (6-12 months) and, if possible, nota split-night study (one-half is diagnostic and one-halfis therapeutic). Split-night studies apply continuouspositive airway pressure (CPAP) for the second half ofthe night and may underestimate the severity of ob-structive sleep apnea syndrome (OSAS). This findingis common because the total sleep time does not meetdiagnostic criteria. For medical and ethical reasons, asplit-night study is mandated in certain cases, espe-cially for patients who are hypoxemic, have arrhyth-mias, or exhibit hypertension during the study. It isagain suggested that all sleep studies for a surgicalpatient comprise attended overnight PSG studies.Home monitoring is acceptable in some cases but isnot suggested for surgical evaluation because a major-ity of these types of studies lack detailed informationon actual sleep parameters.

RADIOGRAPHIC STUDIES

One should avoid trying to make a diagnosis ortreatment plan by using a cephalometric head filmbecause it is only a small part of the workup and is 2Din nature. Measurements that have been commonlyused for evaluating soft tissue and bony anatomy inOSAS include SNA, SNB, PNS-P, PAS, and mandibularplane to hyoid (MP-H); however, their correlation tothe airway and subsequent treatment results are ques-tionable.19 A CBCT study should be obtained, and anairway analysis should be done. The smallest airwaycross section is easily seen and has been correlated tothe extent of the OSA. On the basis of this, thesurgical treatment must primarily address the indi-cated area or areas.19-24

Radiation dose from CBCT scans is significantly lessthan other computed tomographic imaging methodssuch as medical computed tomography (CT) and iswithin the range of traditional dental imaging meth-ods. The superior anatomic information availablefrom 3D imaging is establishing CBCT as the preferredimaging modality for airway evaluation in the adoles-cent and adult populations. Medical CT imaging is
best for infants and young children with SDB. As a

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result of 3D imaging, there is an increased awarenessamong practitioners regarding the relationship be-tween craniofacial structures, airway anatomy, andobstructed SDB. Other applications using 3D imaginginclude evaluation of the changes in the airway result-ing from surgery on the oral soft tissues and the jaws.

The accuracy of predicting airway space changesfrom lateral cephalometric radiographs is � 1.5 mm.In a study by Muto et al,19 a set-back of the mandibleof 1 cm showed a 0.4-mm decrease of the airway inthe anteroposterior dimension only. The usefulness ofthese cephalometric studies is also limited becausedata are obtained in only 2 dimensions. CT is superior,in terms of both accuracy and the ability to measure in3 dimensions. Airway space measurement has beenshown to be quite accurate by use of CBCT scans.20

Multivariate analysis shows both retroglossal space(P � .027) and retropalatal space (P � .0036) to bepredictive of RDI. Li et al21 have also shown a rela-tionship between the airway area and the likelihoodof OSA. There is a high probability of severe OSA withan airway area of less the 52 mm2, an intermediateprobability if the airway is between 52 and 110 mm2,nd a low probability if the airway is greater than 110m2. Lowe et al22 showed that a majority of the

constrictions occur in the oropharynx, with a meanairway volume of 13.89 � 5.33 cm3. Barkdull et al24

showed a correlation between the retrolingual cross-sectional airway and OSA when this area was less than4% of the cross-sectional area of the cervicomandibu-lar ring. Schendel and Hatcher25 have shown thatmeasurement of the 3D airway using a semi-assistedsoftware program (Vultus, Atlanta, GA) from CBCTdata is as accurate as manual segmentation, reliable,and fast. The difference in measured volume of aphantom-filled cone of known volume was � 0.15mL. The Vultus program easily identified the smallestairway area and the largest area while analyzing theairway in successive slices. In addition, we have ver-ified the intraexaminer reliability of this system to amean of 0.26 cm3 out of a total airway volume of 19.5m3. Hakan and Palomo26 have shown that otherigital Imaging and Communications in Medicineiewing systems such as Dolphim3d (Dolphin Imag-ng, Chatsworth, CA) are less accurate. Imaging of thepper airway by use of CBCT data is thus valuable in

dentifying the exact location and nature of the ob-truction in OSA together with the other parameters,elping to refine the surgical approach. Incorporationf this into daily practice will allow practitioners toeadily evaluate and screen their patients for anatomicelated obstructed SDB (Fig 6). This is especially im-ortant in the adolescent population, where manylready seek orthodontic treatment for dentofacialeformities associated with obstructed SDB and
here radiographs are already routinely obtained. i
FIBEROPTIC EXAMINATION

The use of nasopharyngolaryngoscopy can furtherhelp to identify regions (nose, retropalatal area, andtongue base) in the airway that may be a part ofnocturnal obstruction. In addition, it is useful to ruleout other causes of upper airway obstruction such astumors, cysts, lingual tonsils, and laryngeal pathology.

PREOPERATIVE MANAGEMENT

Regardless of age, all subjects should have an ap-propriate medical workup because many of thesepatients have increased medical, anesthesia, and sur-gical risks. In addition, it is imperative that the pa-tient’s health status be maximized to the extent pos-sible before surgery. The patient’s overall nutritionalstatus, including biochemical analyses, should be as-sessed because many of these individuals have re-duced regenerative capacity due to the long-standingillness and associated medical conditions. These con-ditions can also cause skeletal atrophy, trabecularbone loss, and root resorption during treatment.

One of the most important issues in all OSAS pa-tients who undergo surgery is the preoperative andpostoperative airway. Clinical assessments, includingall studies, should be used to decide whether a tra-cheotomy should be performed to protect the airwayperioperatively. Should you have any concern aboutthe airway, a tracheotomy is usually indicated. It isrecommended that it not be done at the same time asa maxillomandibular advancement (MMA) procedurefor 2 reasons: first, the patient’s initial problem is theairway, which is already compromised, and second,combining a tracheotomy with airway surgery willsignificantly increase the risk of infection.

Airway, Airflow, and Surgery

Common nasal surgical procedures include septo-plasty and inferior turbinate reduction by resection orradiofrequency. Airway collapse and a decreased in-ternal nasal angle are treated by spreader grafts orother rhinoplasty techniques to expand and stabilizethe cartilaginous structures of the nose. Thesechanges can easily be seen on a nasal examinationwith a speculum or nasal endoscope but are difficultto quantify without using rhinometry. Subjectivechanges, though, are readily noticed by the patient.Studies of these procedures have mainly looked at thechange on PSG with occasional lateral cephalomet-ric support. Sophisticated 3D airway studies areabsent except for that of Fairburn et al.27 Maxillo-

andibular surgery is performed when there islinical and radiographic evidence of jaw retrusionn adolescents or adults. In addition, MMA surgery
s performed in those individuals who may have a

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normal dentofacial skeleton but who have not com-pletely responded to the other surgical treatmentsand cannot tolerate CPAP. The rule of thumb herehas been an advancement of 1 cm. Studies showgenerally good results as previously stated; how-ever, these have been mainly based on differentcriteria for cure based mainly on PSG, and 3D air-way studies are generally few.28-32 Two-dimen-ional anatomic airway changes on lateral cephalo-etric films in individuals undergoing bimaxillary

dvancement show pharyngeal depth increases inhe magnitude of 48% of the maxillary advancementLi et al21). In addition, these studies show ana-omic differences between individuals with OSAnd normal subjects. However, these studies areimited because of their 2D basis.20,33-38 Three-di-

ensional studies of airway changes after bimaxil-ary surgery are also limited but do show that theurgically induced change is not only in the antero-osterior dimension: important changes also occur

n the lateral dimension. Fairburn et al examined 20atients with OSA who underwent bimaxillary ad-ancement. The patients underwent preoperativend postoperative PSG and CT scans. The authorsound that bimaxillary advancement enlarges thentire velopharynx by elevating the tissues at-ached to the jaws and hyoid. Airways with a de-reased ratio of lateral airway dimension to antero-osterior dimension are more prone to collapse.Although the airway and airflow are coupled, very

ittle attention has been given to the role of airflow intudies of OSAS. The dynamics of airflow in the pha-yngeal airway may play an important role in under-tanding etiologic factors of airway collapsibility inSAS. An ongoing study to assess the characteristicsf airflow in OSAS is being undertaken by Stanfordniversity Sleep Center (Palo Alto, CA) and the De-artment of Aerospace Engineering, University of Cin-innati (Cincinnati, OH). The study focuses on func-ional 3D CT imaging and computational fluidynamics (CFD) modeling using Reynolds-averagedavier-Stokes equations with a k-� turbulenceodel.39 It should be noted that CFD modeling is

sed in many different fields but has only recentlyeen applied for studying the flow associated withSAS.40-42

As a result of this approach, a virtual 3D airwaymodel and the corresponding airflow through theairway passages can be extracted. The modeling ap-proach is used to quantify and compare the flowvariables in the pharyngeal airway before and aftermedical or surgical treatment. The specific flow vari-ables calculated include axial velocity, wall static pres-sure, and wall shear stress.

These flow variables could be associated with pe-
riodic events of airway collapsibility. As the airway b
narrows during sleep, the airway lumen becomessmaller and axial velocity increases at the minimumcross-sectional area. Static pressures decrease at theobstruction, and downstream flow separation causesan abnormal increase in airflow turbulence levels.Further downstream, this separated flow may im-pinge on the pharyngeal airway walls, generatinglarge wall shear stresses at the reattachment region,which over time may have the potential to cause highcycle fatigue of the lumen wall.

CFD modeling can generate precise data on OSASairflow characteristics, which can help to gain insightinto the possible etiology of airway collapsibility inOSAS.43-45 CFD data were obtained and evaluated pre-operatively and postoperatively for a single subjectwith OSAS.1 This subject underwent bimaxillary ad-ancement surgery for severe OSAS.Figure 3 shows the reconstructed pharyngeal airwayodels before and after treatment. End-inspiratory and

nd-expiratory data were calculated for different flowate conditions (5, 10, 15, and 30 L/min), but because ofimited space in this presentation, only end-inspiratoryata for the flow rate of 15 L/min are shown.Preoperatively, the CFD data showed that thereas a large increase in axial velocity (Fig 4A) and theall shear stress values (Fig 4C) at the minimum

ross-sectional areas (locations 2 and 4) in Figures 3nd 4. Large static pressure variations were found asell along the pharyngeal airway length, as de-icted in Figure 4B. As inspiratory flow continues

FIGURE 3. Side views of pretreatment and posttreatment pharyn-geal airway models and comparison of flow variables along air-way. Flow data in the pharyngeal airway were calculated by CFDduring inspiration at a flow rate of 15 L/min for pre- and post-OSAS surgical treatment conditions. Vertical red lines 1 through 5re pre- and post-location markers. Location marker 1 represents

he inlet level of the airway at the posterior nasal choanae. Theutlet of the airway is at location marker 5 at the base of thepiglottis. These location markers 1 to 5 show changes from beforeo after treatment for each of the 3 flow variables.


elow the obstruction site to the supraglottic re-

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gion, flow separation is observed with recirculationupward enhancing turbulence in the jet-like shearlayers. Further downstream, the higher-velocity jetreattaches to the pharyngeal wall, an interactionthat may cause large fluctuations in the wall shearstress and the pressure forces that act on the pha-ryngeal wall.

Postoperatively, the variations in flow variablesalong the pharyngeal airway length (z) almost fullydisappeared, and both airway resistance (based on thepressure difference) and wall shear stresses were sig-nificantly reduced compared with the pretreatmentcase (Fig 4). The flow becomes more streamlined andsmooth, the larger cross-sectional areas associatedwith the surgery being favorable to a laminar-like flow

FIGURE 4. A, Pretreatment and posttreatment axial velocity. At thvelocity values were significantly higher before treatment compasecond. (Z, airway length in meters.) B, Pretreatment and posttreatm15 L/min) before treatment compared with after treatment. Wallretreatment and posttreatment wall shear stress. Pretreatment wonditions. Wall shear stress is measured in pascals. (Z, airway le

chendel, Powell, and Jacobson. Surgical Correction and OSAS. J

situation rather than a turbulent one. A laminar air-

flow is less traumatic than a turbulent airflow, itsinteraction with the airway lumen being minimized.The volumetric airway changes from before to aftersurgery were easily seen, with these changes playinga critical part in the pharyngeal airway and airflowdynamics, as shown in Figures 3 and 4.

The subject’s severe OSAS was completely resolvedafter treatment. The pharyngeal airway after treat-ment showed improved contour and volume that dra-matically changed airflow characteristics. This prelim-inary study will require continued research usingstatic and compliance imaging of the upper airwayfrom the nasal inlet to the outlet at the base of theepiglottis. A better understanding of airflow charac-teristics in OSAS may, in the future, provide a link to

ow sites of the airway at location numbers 2, 3, and 4, the peakh after treatment. Velocity magnitude is presented in meters perll static pressure. Pressure drops were found for the same flow rateressure is measured in pascals. (Z, airway length in meters). C,

ar stress values were significantly higher than the posttreatmentmeters.)

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Decision Algorithm

All factors are then considered in the decision forsurgery. Mild OSAS symptoms are usually associatedwith minimal obstruction at one of the levels, such asthe nose. Soft tissue procedures such as tonsillectomyare performed before the decision for major skeletalsurgery, and the patient is then retested afterward. Asmall anatomic airway, less than 50 mm2, in the ret-ropalatal area is best treated by maxillary advance-ment alone or in combination with mandibular ad-vancement depending on the extent of themalocclusion. A severe Class III malocclusion may becorrected solely by maxillary surgery, for example. Asmall airway at the retrolingual location will mostlikely need a significant mandibular advancement. Anairway closer to 100 mm2 may need only a genioglos-us geniohyoid advancement. This is usually per-ormed as a segmental osteotomy as shown in Figure; however, in cases with associated microgenia, a fulldvancement genioplasty may be performed as longs the central portion of the osteotomy actually isigh enough to capture the genial tubercle. It is our

mpression that airways, which are round in appear-nce, respond less to the surgery and will need largerdvancements than elliptical airways with more lat-ral extension. Multiple levels of obstruction will ne-essitate bimaxillary surgery. In addition, younger andhinner patients respond better than older and obeseatients, in whom there is more soft tissue involve-ent and laxity. If the airway problem is major, the

eptal and/or turbinate corrections are usually com-ined with the jaw surgery. If the airway problem isild to moderate, these surgeries may be done be-

orehand to judge the response before embarking onajor jaw surgery.

Surgical Technique

LIMITING ANESTHESIA RISKS

A laryngeal examination done indirectly or fiberop-tically will give the surgeon and the anesthesiologist achance to assess the possible difficulty of intubationand extubation. To further limit the perioperativerisks, the surgeon may wish to be at the bedside of thepatient on intubation and extubation. Considerationshould be given to extubation in the operating roomand will require the anesthesiologist to have the pa-tient sufficiently awake at the end of the procedure.

SURGICAL PREPARATION

Nasopharyngeal intubation is accomplished with aRoyal Aircraft Establishment (RAE) tube and fixedsuperiorly over the forehead and cranium. Becausemost MMA cases are done with cranial bone grafts,
the tube is sutured to the scalp on the side opposite
from which the graft is taken. Procurement of thecranial graft is the first procedure. Hypotensive anes-thesia is necessary to reduce blood loss and improvevisualization in surgery. This means a systolic pressurebelow 100 and a mean arterial pressure (MAp) ofaround 70 mmHg. Because hypotensive agents areneeded, an arterial line is recommended. In addition,we use a Foley catheter and sequential compressiongarments, and the head is placed higher than theheart. We routinely run light on intravenous (IV)fluids to limit postoperative edema. If bimaxillary ad-vancement is planned for an adult, we request 2 U ofautologous blood before surgery.

SURGICAL TECHNIQUE

The Le Fort I surgical technique is generally similarto that published by other authors with several ex-ceptions.10 The maxilla is approached first, and ahorizontal vestibular incision is made from the firstmolar on 1 side to the opposite first molar. A sub-periosteal dissection is then accomplished, exposingthe anterior face of the maxilla back to the pterygoidprocess and the piriform rims anteriorly. The infraor-bital nerve is visualized and attention taken to notretract forcefully directly on the nerve. The anteriornasal spine is removed with the muscles attached andthe nasal floor elevated; this includes separating theseptum from the maxilla. At this time, we prefer tofracture the pterygoid plates while the maxilla is stillstable. Next, the osteotomy cuts are marked at least 5mm above the apices of the teeth and generally some-what higher to accommodate the plates. The maxillais then mobilized by an anterior downfracture andposterior downfracture. Sufficient mobility must beobtained to advance the jaw passively into the desiredposition, which in many adult patients with OSA is 1cm or greater. The maxilla is rigidly fixed in the newposition with titanium miniplates. An intermediatesplint is frequently beneficial here to align the maxillaand prevent midline discrepancies and sideways andvertical yaw of the jaw. Next, attention is turned tothe mandible. An incision is made along the externaloblique ridge from midramus height to lateral to thefirst molar. The tissues are then elevated at the sub-periosteal level to expose the lateral border of themandible and anterior aspect of the ramus only. Thisis the so-called modified sagittal split technique.46 Thetemporalis muscle must be stripped from the coro-noid process high enough to access the medical ra-mus above the lingual process. The medial ramus isthen exposed to just above and behind the lingualprocess, which can easily be identified with a nervehook and is always at the same level as the mandibularocclusal plane. Retraction is obtained and an osteot-omy made 4 to 5 mm above the lingual process with
a saw or bur to just behind the lingual. It is not

oeamebpiidaamTpaaOb


necessary to carry the cut any further back becausethe split will usually occur at this level anyway and itis safer to end the cut at this level. The osteotomy iscarried along the anterior aspect of the coronoidprocess following the external oblique ridge, wherethey connect to just distal to the first molar tooth orwhere the ridge turns down and the bone becomesthinner. A vertical osteotomy is then made from thisosteotomy inferiorly through the inferior border ofthe mandible, usually in the area of the antegonialnotch. It is extremely important here to cut com-pletely through the inferior border from lateral tomedial; otherwise, the odds of a bad split increasesignificantly. The split is then accomplished with os-teotomes and spreaders. Careful attention must begiven to the position of the inferior alveolar nerveduring this process because it frequently can be foundin the proximal fragment and must be gently teasedout to prevent injury to it. The muscles are detachedfrom the distal fragment at this time. A similar proce-dure is then accomplished on the opposite side of themandible. The mandible is then brought into occlu-sion with the maxilla. An occlusal splint is beneficialwith some built-in overcorrection. The mandible isthen plated or fixed with screws or a combination ofthe two. Rigid fixation is mandatory because the ad-vancements are always quite large over 1 cm andsometimes around 2 cm. In the larger advancements(�1 cm) we prefer to use distraction in the mandible.Slower advancement allows fine tuning of occlusionand limits the force on the condyles. When distractionis used, the rate is 1 mm/d with no latency period.Distraction of the sagittal split segments is easilydone, and the activating wires can be placed in-traorally.47 The maxillary bone grafts are then placedin the advancement gap and either wedged in orsecured with screws. The maxillary vestibular inci-sion is closed with a nasal muscle cinch suture and aV-Y advancement of the vestibular tissues. This pre-vents nasal widening and thinning of the lips, whichis a common complication of bimaxillary advance-ment.46-48 The mandible soft tissues are then closed.Intermaxillary fixation is not used because of thepostoperative airway issues and the fact that rigidinternal fixation is applied. Postoperative trainingelastics are used, however, to guide the jaws into theappropriate occlusion.

POSTOPERATIVE MANAGEMENT

Medical management of the postsurgical patientwith OSAS is more complicated than the usual orthog-nathic patient. A very important care concept is fre-quently missed in the postoperative period. A major-ity of OSAS patients, once in the intensive care unit(ICU), appear stable, but usually, these findings are
noted while the patient is awake. The problem is that
the patient’s condition may dramatically changewhen he or she is overly sedated or asleep. This iswhen a typical OSAS patient’s condition may becomepathologic and he or she have airway problems.32

It is recognized that the surgeon will select and usehis or her familiar routine for recovery and follow-up.We suggest the use of an ICU or monitored bedpostoperatively and careful use of analgesics and an-tihypertensives. The use of a patient-controlled anal-gesia pump is not recommended in sleep patientsbecause the sensitivity to “any” respiratory depressantdrug is so variable that total apnea can be the out-come even in minute doses. A logical and safe methodto control pain in the ICU is the administration ofsmall IV doses at frequent intervals by an ICU nursewho is constantly evaluating any attenuation of respi-ratory rates. The use of nasal CPAP after surgery,especially when the patient is sleeping, is very helpfulto maintain the airway and control edema and tendsto lessen the use of narcotics. After MMO surgery,bilateral nasal trumpet airways must be used to applyCPAP. If not used, air emphysema will be seen in theface and neck and is most unpleasant. Use of CPAPmay also decrease patient anxiety because, if properlyfitted, the patient knows from preoperative experi-ence that CPAP will protect his or her airway whensleeping.14,18,19 Usually the patient may be transferred

ut of the ICU or step-down unit on the first postop-rative day. Pain can be controlled with oral liquidnalgesics or intramuscular injections because IVedication is seldom necessary after the first postop-

rative day. The patient is encouraged to be out ofed ambulating and taking oral liquids on the firstostoperative day. The patient is seen by a nutrition-

st for diet instructions before discharge. Discharges up to the surgeon and patient, and it usuallyepends on pain control and oral intake. The youngdult or adolescent patient is usually easier to man-ge because such patients do not have the overlyingedical problems seen in the adult OSA patient.he main concern is airway management the firstostoperative night. To assist in this, we do notpply intra-arch elastics until 1 to 2 days postoper-tively. Management of the pediatric patient withSA and craniofacial abnormalities is complex andeyond the scope of this article.

FOLLOW-UP

Follow-up is again up to the individual surgeon.Because most surgeries for OSAS may create somedegree of pain, swelling, and airway concerns, it issuggested to have frequent follow-up. It should bekept in mind that surgical edema will usually peak at72 hours, at which point the patient may notice theeffect of swelling and become concerned about his or
her airway. This finding can in some cases be quite

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significant. The usual hospital stay is 2 to 3 days for anadult OSAS MMO procedure. Our patients are seen atday 3 or 4 in the office and again weekly until fullyhealed. Those with CPAP are encouraged to continueuse of the device while sleeping until 1 to 2 weeksbefore the follow-up full-attended PSG study, which isdone at 4 to 6 months. This time interval allows forweight stabilization and neurologic equilibration.20 Aull PSG study can be done as early as 4 to 6 weeksfter surgery in the pediatric population. Should fur-her surgical or medical treatment be necessary, theselans can then be made. If the outcomes of the PSGtudy and EDS are resolved, routine follow-up is at 6onths and then yearly as necessary.

FIGURE 5. Pretreatment facial views. A, Lateral facial view. B,Frontal facial view.

Schendel, Powell, and Jacobson. Surgical Correction and OSAS.
OJ Oral Maxillofac Surg 2011.
WEIGHT IN OSAS

Obesity is considered an important associated fac-tor in the onset and severity of SDB. An elegant studyby Peppard et al49 nicely outlines the cardiovascularisks associated with SDB for weight gain and weightoss. Excess body weight was found to be positivelyssociated with SDB and relative to a stable weight,here a 10% weight gain predicted a 32% increase in

he AHI. This same 10% gain in weight predicted a-fold increase in the odds of moderate to severe SDBeveloping. Conversely, a weight loss of 10% pre-icted a 26% decrease in the same index (AHI). Un-ortunately, weight loss programs in patients withDB have failed miserably. Even with the use of so-histicated behavioral modification programs andariatric surgery, failures are common. Because therean be measurable improvement in patients with SDBhen weight is lost, there has been keen interest in

nvironmental, mechanical, genetic, and hormonalactors that may affect weight in these subjects. Ithould be stressed to each and every overweight

FIGURE 6. Pretreatment radiographs. A, Lateral cephalogram. B,anoramic radiograph.


SAS patient that weight loss is an important part of


the pretreatment or posttreatment management be-cause even modest weight loss may improve surgicaloutcomes.

Clinical Case

A 54-year-old man was seen in consultation for hisOSA, which was debilitating, prevented him fromfunctioning as a pilot, and severely affected his dailylife. The OSA was so severe that it significantly af-fected his health and, if left untreated, may have beenlife-threatening. Weight loss, changes in his sleep po-sitioning, eliminating alcohol, mandibular positioningdevices, uvular surgery, and genioglossus muscle ad-vancement were ineffective in controlling his sleepapnea because of an anatomically small airway quan-tified by a CBCT scan. The Vultus analysis showed asmallest surface area of 59.5 mm2, which—accordingto the literature mentioned previously—falls in theregion of moderate to possibly severe sleep symp-

FIGURE 7. Pretreatment and posttreatment Vultus airway analysairway area was 59.5 mm2. B, After treatment. Total airway volumMMA. C, The smallest airway area presurgery is 56.52 mm2 withwith an airway volume of 20.69 cm3 according to the Vultus airw

Schendel, Powell, and Jacobson. Surgical Correction and OSAS. J Oral M

toms. Overnight PSG showed moderate OSA with anAHI of 21/h, which increased to 49.4/h in rapid eyemovement (REM) sleep. This was associated withbradycardia/tachycardia and an oxygen desaturationto 82%. Sleep stages were also disrupted, with 75% ofthe time spent in stage 2.

Clinical facial and oral examination showed a ClassIII–type malocclusion with maxillary insufficiencyand mild skeletal mandibular asymmetry with chindeviation to the right (Figs 5-7). The patient wasminimally concerned with facial or dental estheticsbut was most interested in correcting the sleep apnea.Maxillary and mandibular arches were misalignedwith midline discrepancy, and old fixed bridges werepresent in the maxillary anterior, replacing missinglateral incisors. There was also a history of clickingand locking of the temporomandibular joint with latereciprocal meniscus displacement bilaterally, whichwas currently stable. Intermittent myofascial pain waspresent upon awakening from nocturnal bruxism.

retreatment. Total airway volume was 10.97 cm3, and smallest20.69 cm3, and smallest airway area was 72 mm2 after 12-mm

l airway volume of 10.97 cm3 above and postsurgery is 72 mm2

lysis.

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CBCT imaging showed adaptive temporomandibularjoint condylar changes.

Presurgical orthodontic therapy consisted of ashort course of treatment to prepare the teeth forsurgery and for the prescribed final occlusion. Beforethe application of orthodontic appliances, a diagnos-tic setup was performed to ascertain the therapeuticocclusion. Impressions of the teeth were taken,poured in stone, and mounted on a semiadjustablearticulator in an unstrained repeatable physiologiccentric relation position. Centric relation was estab-lished disengaging the malocclusion with short-termflat-plane splint therapy and manual manipulation biteregistration techniques. Teeth surfaces on the castswere altered and then duplicated in the mouth withminimal restorative dental procedures to ensure idealpostsurgical occlusal interdigitation. An arch formwas chosen with a template based on the patient’smandibular cancellous and alveolar bone and archform for optimal periodontal health postorthodontictherapy. Edgewise appliances were then bondedto the surfaces of the teeth with custom bases toensure the expression of the intended orthodontictherapeutic occlusion dictated by the diagnosticsetup. Rectangular nitinol (0.016 � 0.022-inch) wirewas placed for torque control and bodily movement.Bodily teeth movement is preferred to minimize rootresorption from tipping. Light orthodontic pressuresand forces are used to achieve optimal tooth move-ment in the shortest possible time with a minimalamount of tissue damage. Rectangular nickel titaniumwires were engaged in 0.018 rectangular slots by useof RMO synergy brackets (Rocky Mountain Orthodon-tics, Denver, CO) ligated to the central bracket wingonly to minimize the friction, during the levelingstage.

The magnitude of orthodontic forces has beenshow to influence the severity of root resorption, andlight orthodontic forces are advocated. Traditionally,heavy forces of up to 3,000 to 4,000g have been usedin orthodontics. Burstone50 and Ricketts51 showedthat 50 to 75g of force was adequate to successfullymove incisors. The pressure necessary for bodilymovement in adults and concluded that 197g/cm2

was optimal.52

An accelerated presurgical phase of treatment wasadvocated because of the health advantages gained bynormalizing the airway and patient oxygen saturationduring sleep in lieu of prolonged presurgical ortho-dontics as traditionally done. Rectangular elgiloy(0.016 � 0.022-inch) passive wires (Rocky Mountain

rthodontics) were placed presurgically with hookslaced interdentally for intermaxillary traction. Post-perative orthodontic treatment was minimal based
n the exactness of the preoperative setup. m
A bimaxillary advancement of 12 mm was thenperformed with the patient under general anesthesiaand the patient admitted for postoperative care; cra-nial bone was used to graft the maxillary defect (Figs8, 9). The surgical technique was performed as out-lined previously. Postoperatively, he did well, andthere were no complications. He was discharged onpostoperative day 4. The entire orthodontic and sur-gical treatment period took less than 9 months. A PSGscan was done at postoperative month 3. The AHI wasthen 5, and he reported physical improvement. Thesmallest airway measured 72 mm2, and the volumencreased to 20.69 cm3 from a preoperative value of0.97 cm3.In summary, bimaxillary surgery plays an important

ole in correction of OSA that is refractive to medical

FIGURE 8. A, Face after treatment. B, Profile after treatment.


anagement or where medical management is not


tolerated and in those patients desiring a definitivecorrection of the problem. The older adult patientusually requires MMA of at least 1 cm based on theliterature and is complex to manage because of thelongstanding associated soft tissue abnormalities atmultiple levels. They may also be medically compro-mised, which complicates the perioperative period.Treatment of the young adult or adolescent patient ismore direct and aimed at correcting the skeletal mal-formation but may be complicated by existing tem-poromandibular joint problems such as condylysis orrheumatoid arthritis. Distraction osteogenesis is play-ing a larger role in the treatment of these patientswho require large advancements (0.1 cm). The wide-spread use of CBCT scans and the recent develop-ment of automated airway analysis such as Vultusprovides the surgeon more refinement in treatmentplanning because the exact site or sites of obstructioncan be readily visualized. Surgical correction can thus

FIGURE 9. A, Lateral cephalometric radiograph after treatment. B,Panoramic radiograph after treatment.

Schendel, Powell, and Jacobson. Surgical Correction and OSAS.J Oral Maxillofac Surg 2011.

be more individually tailored for each patient.

Orthodontists, in preparing patients for jaw surgeryin the treatment of OSA, tend to focus on the mechan-ical aspects of the presurgical and postsurgical occlu-sion. Specialists are acutely attuned to the nuances ofocclusion; often, the biochemistry of the patient andits importance in healing are neglected. Calcium ho-meostasis, parathyroid hormone levels, vitamin D me-tabolites, and the patient’s biochemistry, in general,should be monitored to reduce the metabolic causesof bone loss and tooth resorption.

Acknowledgment

The CFD study was performed by G. Mylavarapu, M. Mihaescu, andE. J. Gutmark (Department of Aerospace Engineering, University ofCincinnati) and N. Powell (Stanford University’s Sleep Center).

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