Fig. 3From: The ‘diamond concept’ for long bone non-union managementDiagrammatic representation of ossification: a Intramembranous ossification. Osteoinductive mediators induce osteogenic MSCs to differentiate into osteoblasts, which lay down osteoid (collagen-1 rich); this mineralises to form an ossification centre, whence mineralisation extends. There is terminal differentiation into osteocytes, becoming entombed in the bone matrix. b Endochondral ossification. Osteoinductive mediators induce osteogenic MSCs to differentiate into chondrocytes; a cartilage matrix is secreted which forms the template for endochondral bone formation. Chondrocytes then undergo hypertrophic differentiation and mineralise the surrounding matrix. They eventually undergo apoptosis—resulting in vascular invasion. Invading blood vessels convey osteoblasts which form bone on the cartilage template [46]Back to article page