Novel Biodegradable Composite of Calcium Phosphate Cement and the Collagen I Mimetic P-15 for Pedicle Screw Augmentation in Osteoporotic Bone.

Osteoporotic vertebral fractures often necessitate fusion surgery, with high rates of implant failure. We present a novel bioactive composite of calcium phosphate cement (CPC) and the collagen I mimetic P-15 for pedicle screw augmentation in osteoporotic bone. Methods involved expression analysis of osteogenesis-related genes during osteoblastic differentiation by RT-PCR and immunostaining of osteopontin and Ca deposits. Untreated and decalcified sheep vertebrae were utilized for linear pullout testing of pedicle screws. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry (DEXA). Expression of ALPI II ( < 0.0001), osteopontin ( < 0.0001), RUNX2 ( < 0.0001), and osteocalcin ( < 0.0001) was upregulated after co-culture of MSC with CPC-P-15. BMD was decreased by 28.75% ± 2.6%. Pullout loads in untreated vertebrae were 1405 ± 6 N ( < 0.001) without augmentation, 2010 ± 168 N ( < 0.0001) after augmentation with CPC-P-15, and 2112 ± 98 N ( < 0.0001) with PMMA. In decalcified vertebrae, pullout loads were 828 ± 66 N ( < 0.0001) without augmentation, 1324 ± 712 N ( = 0.04) with PMMA, and 1252 ± 131 N ( < 0.0078) with CPC-P-15. CPC-P-15 induces osteoblastic differentiation of human MES and improves pullout resistance of pedicle screws in osteoporotic and non-osteoporotic bone.