Mandibular transformations in prepubertal patients following treatment forcraniofacial microsomia: Thin-plate spline analysis

To analyze correction of mandibular deformity using an inverted L osteotomy and autogenous bone graft in patients exhibiting unilateral craniofacial m icrosomia (CFM), thin-plate spline analysis was undertaken. Preoperative, e arly postoperative, and similar to 3.5-year postoperative posteroanterior c ephalographs of 15 children (age 10 +/- 3 years) with CFM were scanned, and eight homologous mandibular landmarks digitized. Average mandibular geomet rics, scaled to an equivalent size, were generated using Procrustes superim position. Results indicated that the mean pre- and postoperative mandibular configurations differed statistically (P < 0.05). Thin-plate spline analys is indicated that the total spline (Cartesian transformation grid) of the p re- to early postoperative configuration showed mandibular body elongation on the treated side and inferior symphyseal displacement. The affine compon ent of the total spline revealed a clockwise rotation of the preoperative c onfiguration, whereas the nonaffine component was responsible for ramus, bo dy, and symphyseal displacements. The transformation grid for the early and late postoperative comparison showed bilateral ramus elongation. A superio r symphyseal displacement contrasted with its earlier inferior displacement , the affine component had translocated the symphyseal landmarks towards th e midline. The nonaffine component demonstrated bilateral ramus lengthening , and partial warps suggested that these elongations were slightly greater on the nontreated side. The affine component of the pre- and late postopera tive comparison also demonstrated a clockwise rotation. The nonaffine compo nent produced the bilateral ramus elongations-the nontreated side ramus len gthening slightly more than the treated side. It is concluded that an inver ted L osteotomy improves mandibular morphology significantly in CFM patient s and permits continued bilateral ramus growth. (C) 2000 Wiley-Liss, Inc.