Biodegradable and titanium plating in experimental craniotomies: a radiographic follow-up study

Plain film radiography and computed tomography (CT) were evaluated in assessing the consolidation of experimental craniotomy lines covered with titanium miniplates or biodegradable self-reinforced poly-L-lactide (SR-PLLA) plates. Two sagittal (2.3-2.5 mm wide and 22 mm long) symmetrical craniotomy lines were made in the skulls of eight young sheep. One craniotomy line was covered with a biodegradable SR-PLLA plate and the other with a titanium miniplate. Both plates were fixed with four titanium miniscrews. Consolidation of the osteotomies was studied using plain film radiography and CT 6, 12, 20, and 52 weeks postoperatively. Microradiography and histology were used for reference. Plain film was not reliable in assessing osseous consolidation because false-positive results were obtained in three osteotomies. Osseous consolidation was more reliably assessed by CT, which showed consolidation on the SR-PLLA side within 20 weeks, whereas none of the titanium-plated lines was consolidated by 52 weeks. Superior consolidation under the resorbable plate was confirmed in histology and microradiography. The radiolucent SR-PLLA plates did not interfere with CT, whereas the titanium plates caused minor CT artifacts.