External fixation is a surgical treatment used to set bone fractures in which a cast would not allow proper alignment of the fracture. In this kind of reduction, holes are drilled into uninjured areas of bones around the fracture and special bolts or wires are screwed into the holes. Outside the body, a rod or a curved piece of metal with special ball-and-socket joints joins the bolts to make a rigid support. The fracture can be set in the proper anatomical configuration by adjusting the ball-and-socket joints. Since the bolts pierce the skin, proper cleaning to prevent infection at the site of surgery must be performed. Installation of the external fixator is performed in an operating room, normally under general anesthesia. Removal of the external frame and bolts usually requires special wrenches and can be done with no anesthesia in an office visit. External fixation is usually used when internal fixation is contraindicated- often to treat open fractures, or as a temporary solution.

External fixation is also used in limb lengthening. People with short limbs can have, for example, legs lengthened. In most cases the thigh bone (femur) is cut diagonally in a surgical procedure under anesthesia. External fixator pins or wires (as above) are placed each side of the 'man made fracture' and the external metal apparatus is used to very gradually push the two sides of the bone apart millimetre by millimetre day by day and week by week. Bone is extremely clever tissue and will gradually grow into the small gap created by this 'distraction' technique. Such a process can take many months. In most cases it may be necessary for the external fixator to be in place for many weeks or even months. Most fractures heal in between 6 and 12 weeks. However, in complicated fractures and where there are problems with the healing of the fracture this may take longer still. It is known that bearing weight through fracture by walking on it, for example, with the added support of the external fixator frame actually helps fractures to heal.