A unidirectional porous beta-tricalcium phosphate material (Affinos®) for reconstruction of bony defects after excision of fibular bone for spinal surgery graft

The aim of this study was to elucidate the bone regeneration-inducing capability of Affinos (R), a newly developed, high-porosity unidirectional porous beta-TCP artificial bone. We compared the ability of Affinos (R) and OSferion (R), a commercially available beta-TCP product, to induce bone regeneration following implantation into bony defects left after fibula harvesting for spinal fusion surgery. Study subjects underwent surgery to harvest non-vascularized fibula grafts for spinal fusion surgery and were implanted with either Affinos (R) (19 patients) or OSferion (R) (15 patients, control group) at the defect site. The minimal and mean follow up periods were 6 and 11 months after surgery, respectively. X-rays of the lower leg taken 1-2 weeks after surgery and at the final follow-up visit were used to evaluate fibular-beta-TCP continuity and fibula defect filling ratio. There was no significant difference in radiographic continuity in the fibula between the two groups. The fibula defect filling ratio for the Affinos (R) group decreased from 0.94 +/- 0.17 at 1-2 weeks to 0.77 +/- 0.14 at 10 months. For the OSferion (R) control group, the fibula defect filling ratio decreased from 0.94 +/- 0.14 at 1-2 weeks to 0.52 +/- 0.27 at final follow-up. The Affinos (R) group showed a significantly higher fibula defect filling ratio compared to that for the OSferion (R) group (p = 0.003). These results indicate that Affinos (R) has slow absorption rates and significant defect filling activity compared with OSferion (R). Thus, Affinos could be a suitable substitute to fill bony defects induced by fibula harvesting for spinal reconstruction surgery. (C) 2019 Elsevier Ltd. All rights reserved.