Development and optimization of biodegradable calcium phosphate-based nanocomposite for the application of spinal fixation

ABSTRACT

Clinical practices in spinal surgery have shown that pedicle screw fixation augmented by polymethyl methacrylate (PMMA) bone cement has improved outcomes for osteoporotic patients, Here, a biodegradable calcium phosphate-based nanocomposite (CPN) exhibiting better anti-pullout ability but similar fluidity and dispersing ability compared to clinically-used polymethyl methacrylate (PMMA) was developed. The present study showed that the axial pullout strength of cement-augmented pedicle screws was increased as the liquid/solid ratio (L/S) of CPN decreased. Mechanical evaluation using ASTM-standard Sawbones showed that the axial pullout force of CPN could reach ∼720 N at the L/S ratio of 0.4 mL/g, while PMMA cannot be injected through the screw. In vitro evaluation in decalcified sheep vertebral models showed that the axial pullout forces of CPN and PMMA were similar, both reaching ∼800 N. The excellent anti-pullout property of CPN clearly suggests its potential for replacing PMMA in the application of cannulated pedicle-screw fixation, worth further study and development for clinical uses.

KEYWORD:

• Calcium phosphate
• nanocomposite
• injectable
• biodegradable
• kyphoplasty

Additional information

Funding

Sponsored by National Natural Science Foundation of China (Project No.81622032 and 51672184), Jiangsu Innovation and Entrepreneurship Program, the Priority Academic Program Development of Jiangsu High Education Institutions (PAPD).