Mandibular hypoplasia in hemifacial microsomia: A cross-sectional study

Background

Hemifacial microsomia (HFM) results from the malformation of facial structures derived from the first and second pharyngeal arches. The ramus of the mandible is the most deformed part of the mandible in HFM, which subsequently affects the linear measurements of the different parts of the mandible. This study evaluated the anatomical differences between the affected and contralateral mandibular ramus and body (MRB) in a select cohort of HFM patients in South Africa.

Methods

This is a serial retrospective study of 20 HFM patients. They were categorised into mild or severe groups by the Pruzansky-Kaban grading and into three age-dependent groups (1–5, 6–12 and 13–19 years old). Linear and angular measurements of the MRB components were recorded from preoperative computed tomography scans to compare severity, age groups, ramus and body index (RBI), and the affected to contralateral (A/C) sides ratio.

Result

Significant differences existed in the linear and angular measurements of the mandible and RBI between affected and contralateral sides, except for the MBL. The mean differences between the mild and severe RBI deformities were insignificant. The A/C ratio was insignificantly smaller in the severe group than in the mild group. Age grouping did not significantly affect the A/C ratio in the mandible ramus and body.

Conclusion

Mandibular asymmetry is more noticeable in HFM patients between 13 and 19 years old. The A/C ratio of the MRB did not worsen with different age groups and severity grading in this study. Hence, clinicians should postpone surgery until HFM patients attain skeletal maturity.