Abstract: Nonunion of longbones is a significant consequence in treating fractures, which is not easy to treat. Thes reviewed the basic knowledge and main progress regarding the cause, pathogenesis, pathophysiology of nonunion, and the methods that may be applied to the treatment of nonunion especially those non-operative one.

Key words: nonunion, fracture repair, treatment, bone mesenchymal stem cells (BMSCs), extracorporeal shock wave treatment (ESWT), pulsed low-intensity ultrasound, review