Broken bones may not heal or do not appear to heal in the customary time are called nonunions.  Pain, weakness and stiffness ensue. 

Reconstructive surgery and immobilization generally help bones to heal.  Internal fixation devices, e.g., pins, screws, metal plates in conjunction with bone grafts – autogenous, allo-, synthetic, or vascularized – aid new bone formation and the union of fractures. Bone Morphogenetic Protein (BMP) and Bone Marrow Aspirate Concentrate (BMAC) are available as bone-growth, stimulating additives to the bony nonunion site.