Le Fort II Distraction With Zygomatic Repositioning: A Technique for Differential Correction of Midface Hypoplasia

Simultaneous Lefort 2 Distraction and Fronto-Orbito-Malar Advancement: Correcting Severe Upper and Midface Retrusion in a Patient With Crouzon Syndrome

Craniofacial syndromes present with exorbitism and airway obstruction as a result of upper and middle facial hypoplasia. Classical subcranial Lefort III (LF III) or monobloc distraction osteogenesis (DO) using an external craniofacial device is used to treat these deformities. These procedures are done during mixed dentition, in most cases, advancing an abnormal face, to a more normal position. In patients with a severe midface retrusion, to achieve differential facial changes, Hopper and colleagues have proposed a combination of LF II distraction with simultaneous zigomatic repositioning. The aim of this presentation is to show a 3-year follow-up of a patient with Crouzon syndrome with severe upper and midface retrusion, who underwent an LF II DO combined with a fronto-malar advancement to achieve cranial and midface expansion and facial ratio normalization. The authors present a variation of technique by Hopper and colleagues;​ a combined intra and extracranial procedure, performing simultaneously a fronto-orbital-malar advancement and LF II DO. The authors performed photographs and craniofacial computed tomography scans to evaluate the patient's appearance and shape of the cranial base. Authors found an important expansion of the middle third of the face with improved facial rations due to differential movement of the bony segments. Lefort II distraction in combination with fronto-orbito-malar advancement is an excellent option for the treatment of patients with severe upper and middle face retrusion. It provides eye globe protection enabling maximal midfacial expansion, resulting in a better functional and esthetic outcome. Results have remained stable after 3 years.

Practical Considerations in Computerized Surgical Planning for Frontofacial Surgery

The field of frontofacial surgery has advanced considerably, building on the pioneering techniques of Paul Tessier, with computerized surgical planning (CSP) emerging as a critical component. CSP has enhanced the precision and efficiency of surgeries for craniofacial dysostoses and hypertelorism, resulting in improved outcomes. This review delves into the importance of understanding orbital anatomy and the crucial bony and soft tissue landmarks essential to the application of CSP in frontofacial procedures, encompassing Le Fort III and monobloc advancements, as well as the correction of hypertelorism.

Comparison of Internal and External Distraction in Frontofacial Monobloc Advancement: A Three-Dimensional Quantification

BACKGROUND

Crouzon syndrome is characterized by complex craniosynostosis and midfacial hypoplasia. Where frontofacial monobloc advancement (FFMBA) is indicated, the method of distraction used to achieve advancement holds an element of equipoise. This two-center retrospective cohort study quantifies the movements produced by internal or external distraction methods used for FFMBA. Using shape analysis, this study evaluates whether the different distraction forces cause plastic deformity of the frontofacial segment, producing distinct morphologic outcomes.

METHODS

Patients with Crouzon syndrome who underwent FFMBA with internal distraction [Hôpital Necker-Enfants Malades (Paris, France)] or external distraction [Great Ormond Street Hospital for Children (London, United Kingdom)] were compared. Digital Imaging and Communications in Medicine files of preoperative and postoperative computed tomographic scans were converted to three-dimensional bone meshes and skeletal movements were assessed using nonrigid iterative closest point registration. Displacements were visualized using color maps and statistical analysis of the vectors was undertaken.

RESULTS

Fifty-one patients met the strict inclusion criteria. Twenty-five underwent FFMBA with external distraction and 26 with internal distraction. External distraction provides a preferential midfacial advancement, whereas internal distractors produce a more positive movement at the lateral orbital rim. This confers good orbital protection but does not advance the central midface to the same extent. Vector analysis confirmed this to be statistically significant ( P < 0.01).

CONCLUSIONS

Morphologic changes resulting from monobloc surgery differ depending on the distraction technique used. Although the relative merits of internal and external distraction still stand, it may be that external distraction is more suited to addressing the midfacial biconcavity seen in syndromic craniosynostosis.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Apert Syndrome: Selection Rationale for Midface Advancement Technique

Apert syndrome is characterized by a wide spectrum of craniofacial clinical features that have been successfully addressed via a variety of midface advancement techniques. Although surgeons have individual preferences as to which specific procedures should be performed to best treat Apert patients, craniofacial plastic surgeons, working in tandem with pediatric neurosurgeons, can identify and evaluate functional limitations and facial morphologic disproportions, and establish appropriate criteria for effective midface advancement technique indication and selection. The purpose of this review article is to present and discuss our rationale for midface advancement technique selection based upon the most common craniofacial characteristics presented by Apert syndrome patients. The present article also provides a grading system that stratifies as major, moderate, and mild, the effect of each midface advancement technique on the different types of Apert syndrome facial features. Surgeons should take into consideration the maximum effect and benefit of each craniofacial osteotomy and how these procedures will alter the craniofacial skeleton. By understanding the long-term effect of each osteotomy on the most common craniofacial characteristics of Apert syndrome patients, craniofacial plastic surgeons and neurosurgeons will be able to customize the surgical procedures they perform in order to achieve the best possible outcomes.

Orthognathic Surgery in Patients with Syndromic Craniosynostosis

Patients with syndromic and nonsyndromic synostosis may have end-stage skeletal discrepancies involving the lower midface and mandible, with associated malocclusion. While orthognathic surgical procedures in this population can be reliably executed, the surgeon must be aware of the unique morphologic characteristics that accompany the primary diagnoses as well as the technical challenges associated with performing Le Fort I osteotomies in patients who have undergone prior subcranial midface distraction.

Influence of Nonsyndromic Bicoronal Synostosis and Syndromic Influences on Orbit and Periorbital Malformation

BACKGROUND

Oculoorbital disproportion in patients with craniosynostosis has similarities and dissimilarities between syndromic and nonsyndromic cases. The authors hypothesized that these two conditions have specific individual influences as they relate to development of the orbital and periorbital skeletons.

METHODS

A total of 133 preoperative computed tomography scans (nonsyndromic bicoronal synostosis, n = 38; Apert syndrome bicoronal synostosis subtype, n = 33; Crouzon syndrome bicoronal synostosis subtype, n = 10; controls, n = 52) were included. Craniometric and volumetric analyses related to the orbit and periorbital anatomy were performed.

RESULTS

Orbital cavity volume was mildly restricted in nonsyndromic bicoronal synostosis (7 percent, p = 0.147), but more so in Apert and Crouzon syndromes [17 percent (p = 0.002) and 21 percent (p = 0.005), respectively]. The sphenoid side angle in Apert syndrome was wider than when compared to Crouzon syndrome (p = 0.043). The ethmoid side angle in Apert patients, however, was narrower (p = 0.066) than that in Crouzon patients. Maxilla anteroposterior length was more restricted in Apert syndrome than Crouzon syndrome (21 percent, p = 0.003) and nonsyndromic cases (26 percent, p < 0.001). The posterior nasal spine position was retruded in Crouzon syndrome (39 percent, p < 0.001), yet the anterior nasal spine position was similar in Apert and Crouzon syndromes.

CONCLUSIONS

Orbit and periorbital malformation in syndromic craniosynostosis is likely the combined influence of syndromic influences and premature suture fusion. Apert syndrome expanded the anteriorly contoured lateral orbital wall associated with bicoronal synostosis, whereas Crouzon syndrome had more infraorbital rim retrusion, resulting in more severe exorbitism. Apert syndrome developed maxillary hypoplasia, in addition to the maxillary retrusion, observed in Crouzon syndrome and nonsyndromic bicoronal synostosis patients.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, II.

Facial Suture Pathology in Syndromic Craniosynostosis: Human and Animal Studies

BACKGROUND

Facial deformities in syndromic craniosynostosis are not only functionally, psychosocially, and aesthetically impairing but also notoriously challenging to reconstruct. Whether facial suture synostosis plays a significant role in the pathogenesis of these deformities is inadequately studied in human patients.

METHODS

The MEDLINE database was queried using a methodologically generated search term inventory. Article inclusion was adjudicated by 2 authors after independent review. Articles provided insight into facial suture involvement in either syndromic craniosynostosis patients or animal models of disease.

RESULTS

Comprehensive review yielded 19 relevant articles meeting inclusion criteria. Mid-20th century craniofacial biologists characterized how patent facial sutures are essential for normal postnatal facial development. They also posited that premature ossification disrupts growth vectors, causing significant dysmorphologies. Recently, facial suture synostosis was found to cause midfacial deformities independent of cranial base pathology in mouse models of syndromic craniosynostosis. Few recent studies have begun exploring facial suture involvement in patients, and although they have paved the way for future research, they bear significant limitations.

CONCLUSIONS

The hypothesis that facial suture synostosis acts in conjunction with cranial base pathology to produce the prominent, multifocal facial deformities in syndromic craniosynostosis may fundamentally alter surgical management and warrants further investigation. Methodically evaluating the literature, this review synthesizes all basic science and human clinical research thus far on the role of facial sutures in syndromic craniosynostosis and elucidates important topics for future research. We ultimately identify the need for rigorous imaging studies that longitudinally evaluate facial osteology across patients with various craniosynostosis syndromes.

Apert Syndrome Outcomes: Comparison of Posterior Vault Distraction Osteogenesis Versus Fronto Orbital Advancement

BACKGROUND

Presenting a wide clinical spectrum and large variety of clinical features, successful treatment of Apert syndrome necessitates performance of sequential multiple surgeries before a patient's facial skeleton growth is complete.The objective of this study is to compare forehead contour asymmetry and clinical outcomes between Apert patients who underwent either fronto-orbital advancement (FOA) or posterior vault distraction osteogenesis (PVDO).

METHODS

A retrospective study was performed on consecutive patients with Apert syndrome who underwent either FOA or PVDO between 2007 and 2019, and participated in at least 6 months of follow-up care. Forehead contour asymmetry and surgical outcomes for each of the included patients were verified through medical records, clinical photographs, and interviews with the parents of the patients. The need for additional craniofacial procedures based on the surgical outcomes of each patient was graded from I to IV utilizing the Whitaker outcome classification system.

RESULTS

Forehead contour asymmetry for all included patients was rated under the Whitaker grading scale as type II (n = 4) 44.4%, type III (n = 2) 22.2%, and type IV (n = 3) 33.3% for FOA, and type I (n = 5) 35.7%, type II (n = 7) 50%, and type III (n = 2) 14.3%, for PVDO (P < 0.05). The average transfused blood volume was 47.77 ± 9.42 mL/kg for patients who underwent FOA, and 22.75 ± 10.31 mL/kg for patients who underwent PVDO (P < 0.05).

CONCLUSIONS

Patients who underwent PVDO had lower forehead contour asymmetry as per the Whitaker outcome grading scale than patients who underwent FOA.

Morphological Basis for Airway Surgical Intervention in Apert Syndrome

OBJECTIVE

Previous studies have explored the restricted nasopharyngeal airway in Apert syndrome patients. This study aims to investigate the segmented airway volume changes with age and directly analyze their correlations with subcranial dimensions and angulations.

METHODS

Ninety-seven preoperative computed tomography scans (Apert, n = 44; control, n = 53) were included in this study, and divided into 5 age-related subgroups. Computed tomography scans were measured using Mimics and 3-matics software.

RESULTS

Before 6 months of age, the nasal cavity in Apert syndrome is reduced by 47% (P = 0.002), which gradually approximates normal thereafter; however, there remained a 30% reduction, compared with controls. It is highly correlated with the anteroposterior length of subcranial space, and the position of maxilla and palate. The pharyngeal airway volume in Apert syndrome patients, younger than 6 months, was larger than normal by 129% (P = 0.013). However, between 2 and 6 years of age, the pharyngeal airway becomes smaller than normal, with a 57% (P = 0.010) reduction in childhood and 52% (P = 0.005) in adolescence. It is closely correlated with the intercondylar and intergonial widths.

CONCLUSIONS

Airway compromise in Apert syndrome patients is attributable more to the nasal cavity in infants, but in the older child, it is the pharyngeal region. The restricted nasal airway in Apert syndrome is correlated with the subcranial space length and width, but independent of cranial base flexion. The pharyngeal airway volume in Apert syndrome is not as highly correlated with craniofacial morphology. Rather, it is impacted by the growth of mandible, which often requires surgical intervention later in childhood.

Le Fort II Distraction with Simultaneous Zygomatic Repositioning

Severe midface hypoplasia is often managed by Le Fort III distraction. Le Fort II distraction with zygomatic repositioning is a modification of the Le Fort III distraction operation aimed to correct abnormal facial ratios of patients with greater central than lateral midface deficiency. The operation starts with Le Fort III osteotomies and is followed by separation and fixation of bilateral zygomas. The central nasomaxillary Le Fort II segment is then distracted to achieve independent movements of the central and lateral midface. The Le Fort II zygomatic repositioning operation has become our procedure of choice for patients with Apert facial dysmorphology.

Distraction Osteogenesis: Mandible and Maxilla

Mandibular and maxillary deformities commonly require surgical intervention. Prior to distraction osteogenesis, traditional modalities involving single-staged translocation and rigid fixation were used to correct these craniofacial anomalies. Distraction osteogenesis has evolved as a compelling alternative for treating aesthetic and functional dentofacial defects. The process of distraction osteogenesis involves three phases-latency, activation, and consolidation-which allow for appropriate translation of the affected craniofacial skeleton. This review will cover the role of distraction for managing congenital and acquired deformities of the mandible and maxilla. This novel technique can be performed at numerous anatomical sites along the craniofacial skeleton to treat a variety of anomalies, which serves as a testament to its adaptability and efficacy. Importantly, distraction osteogenesis also has the ability to simultaneously increase bone length and the overlying soft tissue envelope. This advantage results in larger advancements with reduced relapse rates and improved patient satisfaction. While complications remain a concern, it stands to reason that the measurable benefits observed underscore the power and versatility of distraction osteogenesis.

Magnitude of Horizontal Advancement is Associated With Apnea Hypopnea Index Improvement and Counter-Clockwise Maxillary Rotation After Subcranial Distraction for Syndromic Synostosis

PURPOSE

Subcranial midface distraction is used to treat central midface deficiency in syndromic synostosis. Our aim was to determine which maxillary movements were associated with improvement in measures of obstructive sleep apnea.

METHODS

This was a retrospective cohort study that reviewed patients with syndromic midface retrusion and documented sleep apnea who underwent subcranial midface distraction via either Le Fort 3 osteotomy or Le Fort 2 osteotomy with zygomatic repositioning. The predictor variables measured on cephalograms were the magnitude and direction of midface and mandibular movements. The primary outcome was the change in the apnea hypopnea index (AHI) from polysomnography before and after surgery. The secondary outcomes were volumes of upper airway containing bone spaces calculated from computed tomography scans. Data analysis included linear regression to estimate the effect of distraction vectors on bone space volumes and AHI changes.

RESULTS

We included 18 patients primarily with Crouzon or Apert syndrome. The magnitude of distraction in a horizontal direction was the most significant factor for AHI improvement and primarily expanded the nasopharyngeal space, but with a smaller impact on the oral cavity space. Clockwise palate rotation was most influenced by a downward direction of distraction, with 24° below horizontal creating a neutral advancement. The greater the magnitude of advancement, the more likely a counterclockwise rotation was observed.

CONCLUSIONS

Horizontal magnitude of advancement had the greatest impact on AHI improvement. Vertical lengthening and closure of anterior open bite deformities can be done without compromising airway results as long as total advancement is not compromised. Palate rotation is best controlled by a downward distraction vector, but counterclockwise rotation increases with greater advancement.

Analysis of Airway and Midface in Crouzon Syndromes

BACKGROUND

Crouzon syndrome is associated with severe respiratory impairment of the upper airway due in part to midfacial dysmorphology. We calculated the distinctive nasal diameter and pharyngeal airway volume in patients with Crouzon syndrome and compared them with age-matched control subjects.

METHODS

Children with computed tomography scans in the absence of surgical intervention were included. Computed tomography scans were digitized and manipulated using Surgicase CMF (Materialise). Craniometric data relating to the midface and airway were collected. For all linear measurements, mean percent increases or decreases were calculated relative to the size of control subjects, and volumetric assessment of the airway was tabulated. Statistical analysis was performed using t test.

RESULTS

Twenty-six computed tomography scans were included (control n = 17, Crouzon n = 9). All children were in early mixed dentition. Pharyngeal airway volume was decreased in patients with Crouzon syndrome relative to control subjects by 46% (P = 0.003). The distance from the posterior tongue to the posterior pharyngeal wall decreased 31% when comparing the Crouzon group versus the control (P = 0.04).

CONCLUSIONS

Three-dimensional analysis revealed notably decreased pharyngeal and nasal airway volumes in patients with Crouzon syndrome, but nasal bone tissue and soft tissue measurements showed very little change between patients and control subjects.

Surgical-Orthodontic Considerations in Subcranial and Frontofacial Distraction

Subcranial and frontofacial distraction osteogenesis have emerged as powerful tools for management of hypoplasia involving the upper two-thirds of the face. The primary goal of subcranial or frontofacial distraction is to improve the orientation of the upper face and midface structures (frontal bone, orbitozygomatic complex, maxilla, nasal complex) relative to the cranial base, globes, and mandible. The various techniques used are tailored for management of specific phenotypic differences in facial position and may include segmental osteotomies, differential vectors, or synchronous maxillomandibular rotation.