VERTEBRAL BODY REPLACEMENT USING A POROUS-SURFACED APATITE-WOLLASTONITE GLASS CERAMIC PROSTHESIS IN A SHEEP MODEL: A HISTOLOGIC STUDY

A porous-surfaced AWGC has been developed to offer a superior bioactivity and the initial strength with the high surface friction. Using seven male sheep, spinal defects created at L2/3 and L4/5 were reconstructed anteriorly with two types of AWGC and Kaneda SR. The animals were euthanized at six months after operation and spinal column was obtained. The interface between the AWGC and vertebral body was examined radiologically and histologically. In all cases of porous-surfaced AWGC, the bony union was observed radiologically between the porous surface of AWGC and vertebral body. Five of seven dense AWGC showed a complete displacement of prosthesis despite the rigid fixation. In only one case in which some displacement had occurred, the bone bonding was observed radiologically and histologically. Consequently, the porous-surfaced AWGC showed higher fusion rate compared with the dense AWGC. The high rate of dense AWGC dislodgment substantiates the mechanical superiority of high friction in poroussurfaced AWGC, increasing the initial interface stability.