Effects of resorbable fixation on craniofacial skeletal growth: a pilot experimental study

The effects of fixation composed of resorbable polymers on craniofacial development was investigated in an animal model. Fourteen rabbits had amalgam markers placed bilaterally at the lambdoid, coronal, and frontonasal sutures at 28 days of age. Seven animals (group I) were not plated and served as controls. The other 7 animals (group II) were fixed across the left coronal suture with a 4-hole, compressive resorbable plate. After 6 months, intermarker distances (growth) were measured radiographically, and the amount of fixation degradation was determined by extracted plate weights. Resorbable plating across the coronal suture resulted in local marker constriction adjacent to fixation. Compensatory lengthening of the distal aspect of the frontal bone occurred, however resulting in unaltered total cranionasal lengths compared with that of control animals. Plate degradation occurred with a mean decrease of 7% from their original weights. Molecular weight analysis of the plate differences, however, was not done. This initial study indicates that a large plate size and slow resorption properties of polymer fixation can have a similar restrictive effect on bone growth as that of metal fixation. Whether thinner plates or more rapidly resorbing polymers will permit normal growth in this animal model awaits further testing.