Delayed union and nonunion of a fracture

What it is

Two terms, and time separates them. Delayed union is failure to consolidate within the normally expected time for the fracture type and location. Nonunion is incomplete healing of a fracture where the cortices of the bone fragments do not reconnect 6 months after injury.

Nonunion has two main categories, and it is important to rule out infection: infected, that is septic, nonunion; and aseptic nonunion.

How it presents

Pain on loading the limb; abnormal movement at the fracture site; implants failure; or incidental on follow up x-rays.

Causes and risk

Local factors: a large gap between bone ends; disruption of blood supply, by trauma or by surgery; soft tissue interposition; drainage of the fracture haematoma; and inappropriate fixation, whether too unstable or too rigid.

General factors: poor health, such as DM, IHD or vascular disease; smoking; malnutrition; and a noncompliant patient, over or underloading the limb.