Table 1.

Mechanical and biological factors.

Mechanical Factors [5,6]

Insufficient immobilization Nonoperative treatment Poor internal or external fixation

Excessive motion at the fracture site Malreduction or an unbalanced osteosynthesis system

Biological Factors [5,6]

Local: bone defects, open fracture, infection, soft tissue injuries, segmental fractures, pathological and comminuted fractures, and inter-fragmentary gap Systemic: neuropathy, diabetes, chronic smoking, chronic alcoholism, drugs, and radiation therapy