Abstract: Objective To investigate the causes of postoperative complications of femoral shaft fracture treated with intramedullary interlocking nails Methods A total of 34 patients with femoral shaft fractures admitted to our hospital from 2009 to 2010 were retrospectively studied. They were all treated with intramedullary interlocking nails. The locking nails were removed from 6 patients with delayed union and 3 patients with nonunion to dynamise the fracture. For 1 patient with bone nonunion, the intramedullary interlocking nails were removed, and a larger one and bone grafts were applied. Results Followed up for more than 10 months, the fractures of 6 patients with delayed union and 4 patients with nonunion were completely healed. Conclusions The femoral shaft fracture healing treated with intramedullary interlocking nails depend mainly on intramembranous ossification so that periosteum invasion should be avoided during operations. Dynamisation of the fracture in time can reduce bone nonunion through endochondral ossification.

Key words: Femoral fractures, Nonunion, Intramembranous ossification, Endochondral ossification, Intramedullary interlocking nails