The purpose of an external fixator (“ex-fix”) is to provide a temporizing measure to hold broken bones (usually the femur or tibia) in a reasonable position until further surgery can be performed. The ex-fix provides stability to bones that is particularly important in transfer situations in a combat zone, takes pressure off the surrounding soft tissue and joints, and provides pain relief to the patient.
There are two main types of external fixator constructs:
- Both sets of pins go in the same bone segment.
- Joint-spanning external fixator: one set of pins goes in one bone, and the other set goes into the adjacent bone (e.g. knee-spanning external fixator consists of pins in the femur and the tibia). These are typically performed when the fracture occurs near a joint.
The basic construct consists of the following components:
- Pins: stainless steel pins that are drilled into bone, either on power or by hand. The tips of the pins are threaded to prevent them from backing out of bone.
- 5mm pins are typically used for the femur and tibia.
- The drill tip (circled) of the pin should be advanced through the bone to allow full engagement of the threads.