Evaluation of post-activation mandibular remodelling in children with craniofacial microsomia treated with distraction osteogenesis.

OBJECTIVE: Patients with type IIA craniofacial microsomia (CFM) may benefit from mandibular distraction osteogenesis (MDO) treatment during childhood; however, remodelling of the mandible during the consolidation phase, which may affect the short-term outcomes of MDO, has not yet been quantitatively analysed using computed tomography. Therefore, we aimed to investigate bone remodelling of the mandible in children with type IIA CFM treated with MDO before distractor removal and the factors that influence ramus vertical elongation efficiency. MATERIALS AND METHODS: Twenty-three children with unilateral CFM were studied between 2020 and 2024. Longitudinal computed tomography data (preoperative, end of active phase and at pre-distractor removal) were analysed. Condyle positions and the mandibular cant were analysed using a paired-sample t test. The relapse rates of vertical lengthening and mandibular cant were calculated. The correlation between distraction efficiency and preoperative craniofacial morphology was analysed. RESULTS: The condyle on the affected side moved upwards and backwards by 28.84 ± 4.08 and 2.85 ± 4.33 mm, respectively during the active phase but lost 7.66 ± 2.64 mm of vertical extension during the consolidation phase. The relapse rates for vertical extension of the condyle and occlusal plane were 27% and 35%, respectively. The ratio of mandibular ramus height was positively related to EV. CONCLUSIONS: In children with CFM, attention should be paid to vertical elongation instability and relapse of mandibular inclination during consolidation. Severe mandibular ramus hypoplasia is a preoperative risk factor for vertical skeletal relapse during consolidation. Further efforts are required to reduce the stress that leads to relapse.

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

OBJECTIVE: To characterise the morphology of temporal bone in patients with craniofacial microsomia (CFM). DESIGN: A retrospective study. SETTING: A craniofacial centre. PATIENTS: Ninety-four patients with unilateral craniofacial microsomia. INTERVENTIONS: Mimics 21.0 (Materialise Inc., Belgium) was used to locate temporal bone landmarks on preoperative computed tomography data. The spatial Cartesian coordinate system was established in 3-matic 13.0 (Materialise Inc., Belgium). The coordinates of each landmark and the distances and angles between the landmarks were calculated. A classification system was used to quantify the severity of the zygomatic arch deformity. MAIN OUTCOME MEASURE(S): The bilateral differences in coordinates, linear and angular measurements, and the severity of temporal bone deformity (TTL δ, Psag δ, Paxiδ, and Tsag δ) among the groups were compared using the paired t-test and Kruskal-Wallis test, respectively. RESULTS: Compared to those of the unaffected side, the landmarks of the inner ear and petrous part on the affected side showed a decrease in the Z-coordinate or an increase in the X-coordinate. A superolateral rotation tendency of the temporal bone on the affected side was found. There were no significant differences in the linear and angular measurements between the groups. The degree of zygomatic arch deformation was lower in the mild group; however, no significant difference was found between the moderate and severe groups. CONCLUSIONS: In patients with CFM, asymmetry of the temporal bone and its inner organs (vestibulocochlear organ, facial nerve, and vessels) exists in multiple dimensions; its severity is not completely consistent with the degree of mandibular involvement.

Morphologic Changes of the Temporomandibular Joint in Pruzansky-Kaban Type IIa Hemifacial Microsomia Postmandibular Distraction Osteogenesis.

OBJECTIVE: Mandibular distraction osteogenesis (MDO) is a powerful tool for the correction of hemifacial microsomia (HFM). The temporomandibular joint (TMJ) is the focus of attention in the diagnosis and treatment of HFM. This observational retrospective cross-sectional study aimed to investigate morphologic changes in TMJ post-MDO in type IIa HFM. METHODS: We recruited 48 patients with unilateral type IIa HFM who had completed MDO and mandibular distractor extraction (MDE). Data relating to the length, distance, angle, and volume of the TMJ were measured on 3-dimension models created by the analysis of computed tomography data. Normality analysis was performed by using the Shapiro-Wilk test. Data were compared with the paired t test and Wilcoxon signed-ranks test. RESULTS: The spaces between the affected condyle and the affected glenoid fossa before MDO were all significantly larger than before MDE (P<0.05). The breadth of the affected glenoid fossa before MDO was significantly longer than before MDE (P<0.001). The height of the affected condyle before MDO was significantly longer than before MDE (P<0.001). The volume of the affected condyle before MDO was significantly larger than before MDE (P<0.001). The ratio between the volume of the affected condyle and unaffected condyle before MDO was 0.20±0.13. The ratio between the volume of the affected condyle before MDE and MDO was 0.65±0.32. The resorption rate of the affected condyle post-MDO was 0.35±0.32. CONCLUSION: Herein, we characterized anatomic changes of the TMJ in type- IIa HFM post-MDO. Condylar resorption and the compression of space between the condyle and the glenoid fossa on the affected side were 2 typical manifestations. Our findings enhanced the understanding of the application of MDO on HFM.

Bone Density of the Condyle of Children with Craniofacial Microsomia and its Correlation with Condylar Resorption After Mandible Distraction Osteogenesis.

OBJECTIVE: To investigate condylar bone density (BD) in children with craniofacial microsomia (CFM) and identify factors that contribute to early stage condylar resorption (CR) after mandibular distraction osteogenesis (MDO). DESIGN: Retrospective study. SETTING: Craniofacial department of a plastic surgery hospital. PATIENTS: Fifty-one children with CFM classified as Pruzansky IIa based on complete pre-(T0) and post-MDO (T1) computed tomography (CT) data. INTERVENTION AND MAIN OUTCOME MEASUREMENTS: Mimic 21.0 (Materialise Inc., Belgium) was used to measure bilateral BD and condylar height (CH) and volume (CV) of affected side. Children were split into groups based on either affected side BD or the distraction length (DL,25 mm as cutoff) .Bilateral BD was compared using a paired t-test in each group. The CH and CV of affected side at T0 and T1 were compared. The relative values of the CH and CV (CH ratio) and the volume (CV ratio) of the affected side were compared across the groups. RESULTS: The BD was lower on affected side than on unaffected side. Regarding BD, CH and CV decreased after MDO in group I, while the CH ratio and CV ratio of group I was lower than that of groups II and III. Regarding DL, the CV ratio was lower in Group L than Group S. CONCLUSIONS: The condylar bone quality on affected side is compromised in type IIa CFM. A low BD in combination with a larger distraction distance may increase the risk of CR; therefore, MDO in patients with such characteristics should be postponed.

Condylar resorption post mandibular distraction osteogenesis in craniofacial microsomia: A retrospective study.

The aim of this study was to investigate the characteristics of condylar resorption in craniofacial microsomia (CFM) patients following mandibular distraction osteogenesis (MDO). Patients with unilateral type-IIa and type-IIb CFM, who had completed MDO and mandibular distractor extraction (MDE), were recruited. The height and volume of the condyle were measured on three-dimension models created by the analysis of computed tomography (CT) data. Normality analysis was performed using the Shapiro-Wilk test. Data for the affected and unaffected sides were compared using the paired t-test or Wilcoxon signed-rank test. Data for both type-IIa and type-IIb CFM were compared using the independent-samples t-test or Mann-Whitney U test. The Pearson or Spearman correlation was used to determine the correlations of condylar resorption rate with related measurements. In total, 48 type-IIa and 48 type-IIb CFM patients were included. The condylar resorption rate in type-IIa CFM (0.35 ± 0.32) was significantly associated with the height of the condyle (r = 0.776, p < 0.001) and distraction distance (r = 0.447, p = 0.001), while the condylar resorption rate in type-IIb CFM (0.49 ± 0.46) was significantly associated with the height of the condyle (r = 0.924, p < 0.001). However, there was no significant difference in condylar resorption rate between type-IIa and type-IIb CFM (p = 0.075). In addition to occlusal changes, no other negative symptoms of the TMJ were observed with condylar resorption. Condylar resorption was evident in CFM patients following mandibular distraction osteogenesis, and the condylar resorption rate showed a relationship with distraction distance and condylar height.