THE EFFECTS OF RIGID FIXATION ON CRANIOFACIAL GROWTH OF RHESUS-MONKEYS

A male infant rhesus monkey model was used to examine the growth effect on the craniofacial skeleton caused by osteotomy and three types of fixation: interfragmentary wiring, microplate and screw fixation, and ''extensive'' microplate and screw fixation. The animals (n=12) were allowed to mature until cranial growth was at least 95 percent complete. Direct craniometric measurements were obtained and analyzed for differences in the three treated groups. A group of unoperated male animal skulls also was analyzed as controls (n=5). A subtle visible and measurable restriction of growth in the operated area occurred in all treatment groups. Significant differences (p<0.05) were found in only 4 of the 39 craniometric chords measured. Interfragmentary wiring showed fewer growth-restrictive effects than standard use of microfixation plates. Extensive use of rigid fixation devices caused the greatest degree of growth disturbance. Osteotomy and fixation in the infant rhesus monkey affect craniofacial growth, with the degree of growth restriction increasing with the amount of fixation hardware.