Mechanical evaluation of novel spinal interbody fusion cages made of bioactive, resorbable composites

Osteoconductive and totally bioresorbable spinal/cervical interbody fusion cages were fabricated from a forged composite of raw particulate hydroxyapatite/poly -lactide (u-HA/PLLA) with an u-HA 40 wt% fraction (F-u-HA 40). The mechanical strengths of three types of cages, designed for open-box, screw and cylinder constructs, were compared with those of existing metal and carbon-fiber/polymer cages. Compressive strengths of these composite cages surpassed those of existing metal and carbon-fiber cages. Fatigue resistance to alternate and static compressive loading persisted for longer than the minimum period (6 months) necessary for spinal devices in simulated body fluid (SBF) at 37°C. These novel interbody fusion cages await clinical application in humans.