Surgical Classification of the Mandibular Deformity in Craniofacial Microsomia Using 3-Dimensional Computed Tomography

BACKGROUND: Grading systems of the mandibular deformity in craniofacial microsomia (CFM) based on conventional radiographs have shown low interrater reproducibility among craniofacial surgeons. We sought to design and validate a classification based on 3-dimensional CT (3dCT) that correlates features of the deformity with surgical treatment. METHODS: CFM mandibular deformities were classified as normal (T0), mild (hypoplastic, likely treated with orthodontics or orthognathic surgery; T1), moderate (vertically deficient ramus, likely treated with distraction osteogenesis; T2), or severe (ramus rudimentary or absent, with either adequate or inadequate mandibular body bone stock; T3 and T4, likely treated with costochondral graft or free fibular flap, respectively). The 3dCT face scans of CFM patients were randomized and then classified by craniofacial surgeons. Pairwise agreement and Fleiss' κ were used to assess interrater reliability. RESULTS: The 3dCT images of 43 patients with CFM (aged 0.1–15.8 years) were reviewed by 15 craniofacial surgeons, representing an average 15.2 years of experience. Reviewers demonstrated fair interrater reliability with average pairwise agreement of 50.4 ± 9.9% (Fleiss' κ = 0.34). This represents significant improvement over the Pruzansky–Kaban classification (pairwise agreement, 39.2%; P = 0.0033.) Reviewers demonstrated substantial interrater reliability with average pairwise agreement of 83.0 ± 7.6% (κ = 0.64) distinguishing deformities requiring graft or flap reconstruction (T3 and T4) from others. CONCLUSION: The proposed classification, designed for the era of 3dCT, shows improved consensus with respect to stratifying the severity of mandibular deformity and type of operative management.