Synthetic hydroxyapatite is therapeutically used as bone graft substitute, bone filler, or as coatings to support attachment of bone to metal implants. Here I will present some data on how our group have used hydroxyapatite nanoparticles in combination with various polymers and fabrication techniques to support bone cell differentiation and matrix formation in both static and mechanically stimulated culture conditions. However, the slow degradation rate of hydroxyapatite compromises its osteogenic activities so recently we have collaborated with industrial partners to create a multisubstituted HAP (sHAP) with Magnesium and Strontium. We used a continuous flow method and a Design of Experiments approach to optimise the method and amounts of magnesium and strontium in the hydroxyapatite to increase its solubility, osteogenic integrity and bioactivity. The powders were tested using immortalised human mesenchymal stem cells Y201 in serum-free media and shown to support osteogenesis with no cytotoxicity at any dose tested. A particular need for improved orthopaedic devices is in spine repair where 50% of spinal fusion surgeries need revision partly due to poor osseointegration. Therefore we employed our substituted hydroxyapatite in two spine repair devices 1) Spinal fusion cages: as a coating on a titanium oxide base on a PEEK spinal cage 2) Bone graft substitute: as a particulate phase within a sHAP polycaprolactone composite use as an ink to print an insert for spinal cages which can be used in place of bone graft. Materials containing sHAP were tested for their ability to support osteogenesis and their potential to accelerate the fusion process in spine repair.