[Experimental anterior interbody fusion of the cervical spine. Comparative study between autograft and Al2O3 ceramic implantation]

The purpose of this paper is to compare autograft and Al2O3 ceramic implantation as grafting interbody fusion of the cervical spine of rabbits. Fifty six rabbits were used. In 36 rabbits, Al2O3 ceramic spacers were inserted into the level of C4-5. The spacer is hexahedronic in shape, measuring 6 X 4 X 3 mm. In 20 rabbits, autologous bones, same size as the spacer, were inserted under the same procedure. Animals were killed at 2, 4, 8 and 12 weeks after the procedure. Each material was evaluated radiologically, histologically and biomechanically. The main results found in this study were as follows: Radiologically, periodic anteroposterior and lateral X-rays were taken for the duration of 12 weeks after the procedure. Although the animals with Al2O3 ceramics showed extrusion at higher rate as compared with autografts, they didn't show any collapse and local kyphosis in the procedure site except for extrusive cases. Histologically, new bone formation was observed around Al2O3 ceramics at 4 weeks. And it is clear that Al2O3 ceramics have good histocompatibility. Biomechanically, the maximum resistance to bending or the rigidity of each fixed intervertebrae was measured with the Tensiron testing machine. In the resistance, Al2O3 ceramics were inferior to autograft, but almost equal to the normal motion segment. According to these results, Al2O3 ceramics have many advantages, and results as favourable as those obtained by native bone may be obtained with a proper shape of the implant.