Three-dimensional Analysis of the Temporal Bone Morphology in Patients with Craniofacial Microsomia

Two-step cluster analysis based on three-dimensional CT measurements of craniofacial structures in severe craniofacial microsomia

BACKGROUND

The Pruzansky-Kaban and OMENS classifications do not provide additional details on temporomandibular joint deformities. The aim of this study was to classify and quantitatively define severe forms of craniofacial microsomia based on three-dimensional maxillofacial measurements, focusing on deformities in the zygomatic, temporal, and mandibular bones.

METHODS

Maxillofacial computed tomography (CT) scans of children with severe types of craniofacial microsomia (CFM) from 2010 to 2020 were collected. Three-dimensional measurements of zygomatic arch length, height of mandibular ramus, height of maxilla, and occlusal cant were performed. A two-step cluster analysis was conducted based on zygomatic arch continuity, occlusal cant, and the ratio of the affected side to the unaffected side (A/U ratio) for zygomatic arch length, mandibular ramus height, and maxillary height.

RESULTS

Fifty patients (32 male, 18 female) were included in the study. They were classified into 2 clusters through cluster analysis. Cluster 1 comprised subjects (44% of patients) with continuous zygomatic arches. Cluster 2 comprised subjects (39% of patients) with discontinuous zygomatic arches. The zygomatic arch A/U ratio in cluster 1 was greater than that in cluster 2, with statistical significance observed. Additionally, the maxilla height A/U ratio in cluster 1 was lower than in cluster 2, also with statistical significance. There was no statistically significant difference observed in the ramus height A/U ratio and occlusal cant between clusters 1 and 2.

CONCLUSIONS

Based on craniofacial measurements, severe CFM can be categorized into two types: continuous zygomatic arch and discontinuous zygomatic arch. This cluster analysis complemented the OMENS classification and could assist in the selection and design of prosthetic joints for patients with CFM.

Integrating Virtual Surgical Planning and 3D-Printed Tools with Iliac Bone Grafts for Orbital and Zygomatic Reconstruction in Hemifacial Microsomia Patients

Hemifacial Microsomia (HFM) is the second most common congenital craniofacial malformation syndrome, and the complexity of HFM makes its treatment challenging. The present study aimed to introduce a new approach of utilization of virtual surgical planning (VSP) and 3D-printed surgical adjuncts for maxillofacial reconstruction. Five HFM patients were included in this study. All participants were provided with a full VSP, including the design of osteotomy lines, the design and fabrication of 3D-printed cutting guides, fixation plates, and titanium mesh for implantation. With the assistance of 3D-printed cutting guides and fixation plates, the orbital deformities were corrected, and a 3D-printed titanium mesh combined with iliac cancellous bone graft was applied to reconstruct the zygomatic arch. The surgical accuracy, effectiveness, and bone absorption rate were evaluated. All patients completed the entirely digital treatment process without experiencing severe complications. The surgical adjuncts were effective in aligning the movement of the bone segments with the surgical plan, resulting in mean 3D deviations (1.0681 ± 0.15 mm) and maximum 3D deviations (3.1127 ± 0.44 mm). The image fusion results showed that the patients' postoperative position of the maxilla, zygoma, and orbital rim was consistent with the virtual surgical plan, with only a slight increase in the area of bone grafting. The postoperative measurements showed significant improvement in the asymmetry indices of Er (AI of Er: from 17.91 ± 3.732 to 5.427 ± 1.389 mm, p = 0.0001) and FZ (AI of FZ: from 7.581 ± 1.435 to 4.070 ± 1.028 mm, p = 0.0009) points. In addition, the observed bone resorption rate at the 6-month follow-up across the five patients was 45.24% ± 3.13%. In conclusion, the application of VSP and 3D-printed surgical adjuncts demonstrates significant value in enhancing the precision and effectiveness of surgical treatments for HFM. A 3D-printed titanium mesh combined with iliac cancellous bone graft can be considered an ideal alternative for the reconstruction of the zygomatic arch.