Osteoinductive bone substitutes are in their developmental infancy and a paucity of effective grafts options persists despite clinical demand. Bone mineral substitutes such as hydroxyapatite cause minimal biological activity when compared to osteoinductive systems present biological growth factors in order to drive bone regeneration. We have previously demonstrated the in-vitro efficacy of a bioengineered system at presenting growth factors at ultra low-doses. This study aimed to translate this growth factor delivery system towards a clinically applicable implant.

Osteoinductive surfaces were engineered using plasma polymerisation of poly(ethyl acrylate) onto base materials followed by adsorption of fibronectin protein and subsequently growth factor (BMP-2). Biological activity following ethylene oxide (EO) sterilisation was evaluated using ELISAs targeted against BMP-2, cell differentiation studies and atomic force microscopy. Scaffolds were 3D printed using polycaprolactone/hydroxyapatite composites and mechanically tested using a linear compression models to calculate stress/strain. In-vivo analysis was performed using a critical defect model in 23 mice over an 8 week period. Bone formation was assessed using microCT and histological analysis. Finally, a computer modelling process was developed to convert patient CT images into surface models, then formatted into 3D-printable scaffolds to fill critical defects.

Following EO sterilisation, there was no change in scaffold surface and persistent availability of growth factors. Scaffolds showed adequate porosity for cell migration with mechanical stiffness similar to cancellous bone. Finally, the in vivo murine model demonstrated rapid bone formation with evidence of trabecular remodelling in samples presenting growth factors compared to controls.

Introduction and objectives

Intramedullary nailing is indicated to stabilization of tibia shaft fractures. Intramedullary nailing through an infra-patellar incision is commonly the technique of choice. While intramedullary nailing of simple diaphyseal fracture patterns is relatively easy, proximal tibia fractures, extremely comminuted/segmental tibia fractures, politrauma with multiple fractures in both extremities and reconstruction of bone loss segment with stiffness of the knee joint can be very challenging to treat.

A novel technique for intramedullary tibia nailing through the patella-femoral joint is described. This technique allow extension tibia during intervention time and it supplies easier reduction of the pattern of fracture above. The purpose of our investigation was to evaluate the use of this new technique in described above pattern fracture and patient situation; because we have thought that new technique can perform better outcomes in this situations.