Retrognathia, or posterior positioning of the mandible relative to the cranial base, is a complex condition that may have various etiologies and effects on patients of all age groups. The range of those affected spans from neonates born with congenital conditions or syndromes to adults who suffer from growth abnormalities, systemic disease, or posttraumatic deformities. The consequences of retrognathia are many and vary in severity from mild aesthetic abnormalities to emergent airway obstruction. Within this range of consequences exist an entire spectrum of effects on the upper airway.

The airway compromise, regardless of the degree, may result in part, entirely, or not at all from the retrognathia itself. Discerning the precise role played by posterior mandibular positioning in a particular case of airway obstruction is both challenging and controversial. Accurate determination of the contribution of the retrognathia to the airway compromise is paramount to appropriate treatment planning. Once the diagnostic challenge is surmounted, even greater controversies and challenges present in determining the optimum short-term and long-term strategies for managing the patient’s airway. This paper presents a general approach to airway management in the retrognathic patient (Fig. 75—1).

Background

Understanding the factors that determine mandibular positioning enhances one’s ability to identify the retrognathic mandible and its effects on the upper airway. The mandible articulates with the petrous portions of the temporal bones via bilateral temporomandibular joints. The size, location, and orientation of the petrous portions of the temporal bones affect the position of the mandible in both anteroposterior and superoinferior planes of space.¹ The base of the skull, therefore, is the first variable affecting mandibular positioning. From this articulation forward, the size and morphology of the mandibular condyles, rami, bodies, and symphysis determine the size and position of the mandible relative to the cranial base. This size and position have been shown to have important effects on the upper airway² via various mechanisms. One such mechanism is that of tongue position. Tongue position is affected by virtue of the space available for the tongue to rest as dictated by mandibular size, and by the genioglossus muscle³ pull, which is affected by the anteroposterior location of the genial tubercles located on the lingual cortex of the anterior mandible. Other means by which mandibular position affects the upper airway are by various muscle attachments from the mandible to other structures that affect the airway. Most important are the attachments of the genioglossus muscle, the geniohyoid muscle, and the anterior bellies of the digastric muscles.⁴

Discussion

Because mandibular position frequently plays an important role in airway patency,^{2, 4, 5} one should always question the status of the airway in any patient with retrognathia (Fig. 75—1-a). If airway obstruction is not known to be present, the patient should be questioned and examined for signs and symptoms of obstructive sleep apnea (Fig. 75—1-b). If there is a high index of suspicion for some degree of obstruction, further evaluation, such as polysomnography, cardiovascular and pulmonary examinations, and in some cases, laboratory tests and additional studies, is warranted (Fig. 75—1-c).

The first step in managing the airway of the retrognathic patient with known airway compromise is to assess the severity and urgency of the obstruction (Fig. 75—1-d). Historically, retrognathia in association with emergent airway compromise has been necessarily addressed in neonates and infants born with syndromes associated with posterior positioning of the mandible and/or micrognathia.^{6, 7} Such congenital conditions include, but are not limited to, Pierre Robin sequence, Treacher Collins syndrome, Goldenhar syndrome, and isolated first and second branchial arch syndromes.^{8, 9}

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