A novel calcium phosphate–based nanocomposite for the augmentation of cement-injectable cannulated pedicle screws fixation: A cadaver and biomechanical study

• Published in: Journal of orthopaedic translation 2020-01, Vol.20, p.56-66
• Main Authors: Sun, Haolin, Liu, Chun, Li, Xuwen, Liu, Huiling, Zhang, Weiguang, Yang, Huilin, Li, Chunde, Yang, Lei
• Format: Article
• Language: English
• Subjects: Calcium phosphate–based cement; Injectable; Original; Osteoporosis; Pedicle screw; PMMA
• ISSN: 2214-031X; 2214-0328
• DOI: 10.1016/j.jot.2019.08.001

Both polymethylmethacrylate (PMMA) and traditional calcium phosphate–based cements have some deficiencies as augmentation materials for pedicle screw fixation. Here, a novel calcium phosphate–based nanocomposite (CPN) for the augmentation of pedicle screw fixation was developed based on previous study, and the handling properties, biomechanical performance, and biodegradation behaviour of CPN were evaluated and compared with clinical PMMA by means of a cadaver study and animal tests. Bone mineral density of the lumbar vertebrae was tested. Pedicle screws were placed into the lumbar vertebrae under the guidance of three dimensionally printed templates; each of which was designed based on computed tomography (CT) reconstruction of each vertebrae ​and augmented with either PMMA or CPN. X-ray and CT scan were used to evaluate the accuracy of screw placement and dispersion as well as interdigitation of bone cement. The axial pull-out strength and maximum torque were tested using a mechanical testing machine. Degradation behaviour of CPN was evaluated by in vitro immersion tests for 8 weeks and in vivo rabbit femur defect model for up to 6 months, respectively. Standard mechanical tests revealed that PMMA was much stronger than CPN after setting (compressive strength 95 vs. 49 ​MPa, respectively, p ​