Maxillary Changes Following Facial Bipartition - A Three-Dimensional Quantification

Skeletal changes after midface surgery in patients with craniofacial deformities: a three-dimensional quantification method

To determine the skeletal changes after midface surgery in patients with syndromic craniosynostosis who underwent Le Fort III (LFIII), monobloc (MB), or facial bipartition (FB). This was a retrospective study including 75 patients: 33 treated by LFIII, 29 by MB, and 13 by FB. Twenty-five had a diagnosis of Apert, 39 Crouzon, and 11 craniofrontonasal syndrome. A three-dimensional mesh was created from the preoperative scan and registered to the postoperative scan to visualise the advancement. LFIII at age 7-12 years effectuated a higher mean advancement in the maxillary (15.5 mm) and zygomatic (7.6 mm) regions when compared to ≥13 years (10.2 mm and 5.5 mm). After MB, mean advancement of the fronto-orbital region was higher at <7 years (16.4 mm), and similarly lower at ages 7-12 (13.8 mm) and ≥13 (12.5 mm). The mean preoperative inter-dacryon distance (34.4 ± 4.4 mm) was reduced by 8.7 ± 4.2 mm after FB without distraction (n = 10). More advancement was seen when midface surgery was performed at a younger age, due to more severe cases and a desire for overcorrection. The highest mean advancement was observed in the fronto-orbital region. Antero-inferior rotational movement was seen after all three techniques.

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.