Triphasic ceramic scaffold in paediatric and adolescent bone defects.

We evaluated novel triphasic hydroxyapatite tricalcium phosphate calcium silicate scaffold (HASi) in the management of paediatric bone defects. Their main advantage is considered to be adequate strength and stimulation of bone formation without resorting to autograft. A total of 42 children younger than 16 years of age were recruited over a period of 1 year and were treated with this synthetic bone substitute as a stand-alone graft for pelvic, femur, calcaneal and ulnar osteotomies, cystic bone lesions, subtalar arthrodesis and segmental bone defects. Forty children, 22 boys and 18 girls, mean age 8.3 years and a mean follow-up of 18.51 months, were available for evaluation. Analysis showed that younger age, cancellous defects and no internal fixation were associated with significantly faster healing. Partial incorporation was observed in 22.5% and complete incorporation in 77.5% of cases at 18 months of follow-up. Sex, type of defect, BMI and the shape of the ceramic graft did not significantly affect the rate of healing. Complications attributable to HASi included four nonunions, three of which were diaphyseal. HASi was found to be safe in children with cancellous or benign cavitatory defects. It is not suitable for diaphyseal and segmental bone defects as a stand-alone graft.

Surface-phosphorylated copolymer promotes direct bone bonding.

The bone bonding potential of surface-phosphorylated poly (2-hydroxyethyl methacrylate-co-methyl methacrylate) [poly (HEMA-co-MMA)] has been investigated and compared with commercially available poly (methyl methacrylate) bone cement (CMW1 radiopaque, Depuy; Johnson & Johnson, Blackpool, Lancashire, England, United Kingdom) as control. Poly (HEMA-co-MMA) is synthesized by free radical-initiated copolymerization and surface functionalized by phosphorylation. The X-ray photoelectron spectroscopy confirms the presence of surface-bound phosphate groups on poly (HEMA-co-MMA). The surface-phosphorylated poly (HEMA-co-MMA) promotes in vitro biomineralization, cell viability, cell adhesion, and expression of bone-specific markers such as osteocalcin and alkaline phosphatase. The bone implantation study performed in rabbits as per ISO 10993-6; 1994 (E) shows that surface-phosphorylated poly (HEMA-co-MMA) elicits bone bonding and new bone formation. New woven bone trabeculae are formed at the defect site of surface-phosphorylated poly (HEMA-co-MMA) within 1 week, while for control sample, inflammatory cells--predominantly, macrophages, fibroblasts, and fibrocytes--are present at the cortical margins around the defect. The 4 and 12 weeks postimplantation results show that the major part of the defects around the surface-phosphorylated poly (HEMA-co-MMA) implant is bridged with new woven bone, with significant remodeling (evident from resorption bays) along both the margins of the defect, but for control implants, the defects are only partially closed, with slight remodeling along the margins, but most of them are separated by fibrous tissue.