A Range of Condylar Hypoplasia Exists in Treacher Collins Syndrome

Purpose: Temporomandibular joint malformation is a complex deformity in Treacher-Collins syndrome (TCS); however, it is not well characterized. This study aimed to better clarify this pathology by volumetrically assessing the mandibular condyle in patients with TCS compared with normal controls and the relative contribution of the condyle to hemimandibular volume. Materials and Methods: A retrospective, cross-sectional analysis of pediatric patients with TCS and unaffected controls was performed. The study sample was comprised of Treacher Collins patients. The predictor variable in this study was disease status (TCS diagnosis vs control), and the outcome variable was condylar volume. Demographic information was collected, and 3-dimensional computed tomographic data were analyzed by computerized segmentation (Materialise). Volumes were obtained for TCS condyles and compared with age-matched controls using the Student t test. Results: Three-dimensional computed tomographic scans were identified in 10 patients with TCS (20 sides) and 14 control subjects (28 sides). The TCS group included 4 female and 6 male patients (age, 0.3 to 213 mo; average age, 66.5 mo). The control cohort included 7 female and 7 male subjects (average age, 68.8 mo). Evaluation of the mandibular condyle showed that patients with TCS had a significantly smaller condylar volume than control patients (TCS, 178.28 +/- 182.74 mm(3); control, 863.55 +/- 367.20 mm(3); P < .001). Additional intragroup analysis showed no significant differences between the left and right condylar volumes in the TCS group (P = .267). In addition, the condyle for patients with TCS represented a smaller proportion of hemimandibular volume compared with controls (1.37% vs 4.19%, respectively; P < .001). Conclusions: The results of the this study suggest that condylar volumes are significantly smaller in patients with TCS compared with age-matched controls, and the condyle represents a smaller fraction of the total mandibular volume for patients with TCS than in unaffected children. In addition, there is considerable variability of condylar size in patients with TCS. These facts portend treatment decisions because a functional temporomandibular joint is necessary and may need to be reconstructed as a first stage before effective implementation of distraction procedures. c 2013 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 71:393-397, 2013