External fixation

External fixation is a method for stabilizing open limb fractures and other complex limb injuries (e.g. extensive soft tissue or vessel injuries). It is mostly a temporary measure until definitive surgical treatment (open reduction and internal fixation) can be safely performed 1. It is also used for fracture management in children (where pins could damage the growth plate), during limb-lengthening procedures, and after corrective osteotomies 2.

Radiographic features

External fixators are made of intraosseous metallic pins and/or wires, and are thus well depicted on either plain film and CT. The pins are connected by external steel or carbon fiber rods. Assessment of pin placement is essential, ideally, the pins should penetrate both the near and far cortex of the bone being stabilized, without significantly protruding into soft tissues on the far side. Intraarticular placement should be avoided 2. Signs of hardware failure or loosening should be commented upon. On plain film summation of different parts of the hardware often requires additional views.

Practical points

External fixators are prone to superinfection as they are partly extracorporeal. Without appropriate care, the entry point of the pins, rapid infection of the pin-track can ensue 2.