Why does a fracture become a non-union?

Although the exact causes are unknown, several local and systemic factors contribute to the development of a non-union.

Systemic factors: age, metabolic conditions, nutritional conditions, general health condition, smoking, alcohol consumption, drug use, diabetes, genetics.

Local factors: exposed fracture, infected fracture, bone segment with poor vascularisation, unstable synthesis, immobilisation for an insufficient amount of time.