Craniofacial growth in rabbits after rigid or semi-rigid fixation of the frontonasal suture.

Treatment of craniofacial dysostosis involves complex remodeling of the cranium and facial bones. Maintenance of the newly positioned segments may be achieved by rigid fixation using plates; however, there is concern that, over time, these plates may interfere with normal growth. The purpose of this study was to test a method of "semi-rigid" fixation of an osteotomy of the frontonasal suture in juvenile rabbits by comparing standardized parameters of craniofacial growth after conventional suture plating with the experimental plating method and with growth after sham operation. Forty-five, 6-week-old, weanling rabbits were divided into three groups of 15 each (12 for cephalometry, 3 for histological examination): (group 1) control, sham operated; (group 2) rigid fixation; (group 3) semi-rigid fixation. Rabbits were maintained for 14 weeks. Craniofacial growth was assessed using three-dimensional image analysis techniques. Measurements were subjected to statistical analysis (one-way analysis of variance) to compare the three treatment groups. Pairwise comparison of means between the treatment groups was done using Bonferroni's method at the 0.05 significance level. Semi-rigid fixation permitted significantly more normal growth of the developing rabbit head than rigid fixation in total snout length, total vault length, left and right midface height, and left orbital length. Both semi-rigid and rigid fixation significantly restricted growth compared with sham operated animals in left and right posterior midface height, right orbital length, right and left nasal bone length, and left parietal width. There were no significant differences in the growth of all other parameters measured.