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:

1. Both sets of pins go in the same bone segment.
2. 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:

1. 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.
   1. 5mm pins are typically used for the femur and tibia.
   2. The drill tip (circled) of the pin should be advanced through the bone to allow full engagement of the threads.