Interbody lumbar fusion using a carbon fiber cage implant versus allograft bone. An investigational study in the Spanish goat.

STUDY
DESIGN: A carbon fiber-reinforced polymer implant, designed to aid interbody lumbar fusion, was tested biologically in an experimental surgical model. Twenty-seven Spanish goats had interbody lumbar fusion surgery in a randomized protocol. Seventeen goats were implanted with the carbon fiber-reinforced polymer cage packed with autologous bone, and 10 goats were implanted with ethylene oxide-sterilized allograft bone.
OBJECTIVES: To determine fusion success, biocompatibility of the carbon polymer material, and possibility of carbon wear debris at intervals after surgical implantation.
METHODS: Goats were killed at 6 months, 12 months, and 24 months and full-body autopsies were done. Spine specimens were studied by plain radiography, three-dimensional reformatted computed tomography studies, and histology.
RESULTS: At 6 months, one of three allograft implantations showed histologic and radiographic fusion, whereas five of five carbon fiber-reinforced polymer cage fusions showed at least partial fusion. At 12 months, two of three allograft implantations and five of five carbon fiber-reinforced polymer cage fusions were solidly fused. At 24 months, five of five allograft implantations and three of three carbon fiber-reinforced polymer cage implantations were solidly fused.
CONCLUSIONS: Interbody fusion using a carbon cage implant packed with autologous bone achieved a quicker and more reliable fusion compared with ethylene oxide-sterilized allograft bone. There were no adverse effects from the implant material.