Experimental calvarial growth disturbance by micro-plate and screw fixation.

A study was designed to help ascertain the effects of rigid internal fixation in the growing skull. Five piglets underwent plating of the left coronal suture at 3 weeks of age. At the time of surgery metal markers were placed to follow bone growth. Cephalometric radiographs, direct osteometry at sacrifice, gross pathological examination and specimen radiography revealed a localized disturbance of growth. There was a restriction of sutural displacement and appositional bone growth at the site of the plate. Local restriction of sutural growth was almost complete during the experimental period. There was an alteration to a 'mature' suture morphology, without synostosis, of the suture on the plated side not seen on the control side. A plagiocephalic pig was not produced nor was there an orbital deformity. A large local contour deformity developed and by the end of the experimental period the plate had become completely incorporated in bone. These effects were statistically significant as well as clinically significant. The clinical use of this type of fixation in reconstructive surgery of the infant craniofacial skeleton is questioned in light of the result.