Adjustable Polyurethane Foam as Filling Material for a Novel Spondyloplasty: Biomechanics and Biocompatibility

OBJECTIVE: To investigate the biomechanics and biocompatibility of polyurethane (PU) foam with adjustable stiffness as a filling material for a novel spondyloplasty that is designed to reduce the risk of postoperative adjacent level fractures. METHODS: Sixty individual porcine lumbar vertebrae were randomly split into 4 groups: A, B, C, and D. Group A served as unmodified vertebral body controls. Groups B, C, and D consisted of hollowed vertebral bodies. Vertebrae of groups C and D were filled with adjustable PU foams of different stiffness. The compressive strength and stiffness of vertebrae from groups A-D were recorded and analyzed. 3T3 mouse fibroblasts were cultured with preformed PU foams for 4 days to test biocompatibility. RESULTS: The strength and stiffness of the hollowed groups were lower than in group A. However, the differences were not statistically significant between group A and group C (P > 0.05), and were obviously different be- tween group A and group B or group D < 0.01 and <0.05, respectively). Moreover, the strength and stiffness after filling foams in group C or group D were significantly greater than in group B (P < 0.01 and