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.