2.2.1 Open fractures

External fixation is one option for the temporary or definitive skeletal stabilization of open fractures, in particular those with severe soft-tissue injury [1].

It is also useful in cases where there is a higher risk of infection, eg, delayed treatment and/or wound contamination. It has long been a useful device for managing such injuries and remains the gold standard for several reasons.

External fixation can be applied with minimal trauma, avoiding additional damage to soft tissues and bone vascularity.

2.2.2 Closed fractures

In closed fractures, external fixation is indicated for temporary bridging in severe polytrauma [2, 3] and severe closed soft-tissue contusions or degloving.

Delayed open reduction is recommended for some closed fractures with severe soft-tissue injury and polytrauma. In these cases, a temporary external fixator may be applied outside the zone of injury and, ideally, outside the zone of potential surgery to maintain the alignment of the limb while treating the soft tissues.

2.2.3 Polytrauma

External fixation should be considered for damage-control surgery in polytrauma. It can be performed rapidly and, because it is a minimally invasive technique, it will minimize any additional surgical insult to the patient [2, 3].

External fixation can be used for almost every long bone and large joint fracture. The main advantage of this approach is the rapid achievement of relative stability that helps to control pain, decrease bleeding, lessen systemic inflammatory response syndrome [3], and facilitate nursing care.

2.2.4 Articular fractures

Perfect joint reconstruction with interfragmentary compression and absolute stability, allowing early pain-free motion, is the treatment goal for articular fractures. This goal can be achieved by ORIF or, for simple fracture patterns, by a combination of interfragmentary lag screw fixation with an external fixator. This is generally a temporary measure designed to protect delicate soft-tissues associated with an unstable or complex articular fracture, or to cope with joint dislocations that do not permit primary definitive internal fixation or ligament repair. Any major joint can be bridged in this way [4, 5] but it is most common in the wrist, knee and ankle.

2.2.5 Bone or soft-tissue loss

External fixators provide the surgeon with the unique opportunity to manage major soft tissue and bone loss by primary shortening of the limb followed by secondary distraction osteogenesis to restore limb length. In some cases this will avoid the need for major plastic surgical reconstruction.

2.2.6 External fixator as a tool for indirect reduction

The external fixator can be used as a tool to perform indirect reduction during minimally invasive osteosynthesis [6]. Once the fracture has been reduced, the position is maintained by locking the external fixator while the internal fixation plate or intramedullary nail is inserted and secured. In some situations, when the internal fixation does not provide adequate stability, the external fixator can be left in situ for a short period to provide additional support.

One way to achieve minimally invasive intraoperative reduction is to apply the modular external fixator as an external reduction device.

External fixators or femoral distractors have proven their value for intramedullary nailing of the tibia. Steinmann pins are inserted in the proximal tibial, posterior to the entry point for the intramedullary nail, and in the calcaneus, and joined by long tubes. This achieves well-balanced local traction with which length, alignment, and rotation can be adjusted; the intramedullary nailing can be performed without obstruction, with the knee joint in flexion or extension ( Video 3.3.3-1 ).

3.2.1 Diaphysis

It is essential to avoid thermal damage to the bone when inserting a pin or Schanz screw into hard cortical bone.

The sharper the drill bits or screws, the less heat is generated. The temperature rises as the insertion speed increases. Burning the bone can be a serious problem and may result in early loosening due to ring sequestrum formation and/or infection. A correctly inserted pin or screw should find purchase in the opposite cortex but not protrude too far beyond it.

3.2.2 Metaphysis

In metaphyseal bone, heat generation is not such a problem. It may be safer to use self-drilling screws since it is easy to miss the predrilled hole. Joint penetration must be avoided because of the danger of pin-track infection spreading into a joint. The surgeon must be aware of the insertion of the joint capsule.

3.2.3 Safe zones

To avoid injuries to nerves, vessels, tendons, and muscles, the surgeon must be familiar with the anatomy of the different cross-sections [8] of the limb and make use of the safe zones for pin placement ( Fig 3.3.3-2 ).

In the tibia, it is not necessary to place the Schanz screws at the anterior tibial crest in a uniplanar application. Stability in the tibial crest is high due to the thick cortex. However, excessive purchase in the cortex is usually not required because of the adequate thickness of the anteromedial tibial wall and bicortical anchorage of the Schanz screws. The drilling of a hole in the thick tibial crest may be associated with excessive heat generation and subsequent necrosis of the bone. Insertion of a Schanz screw at the tibial crest may be difficult as the tip of the drill bit may slip medially or laterally, damaging the soft tissues. In the distal tibia, there is a risk of damage to the tendons of the tibialis anterior and extensor digitorum muscles and the most distal pin sites also have the highest infection rate. There is, however, a safe zone on the anteromedial aspect of the tibia, where Schanz screws can remain for a long period without infection.

4.1.1 Schanz screws

Schanz screws are partially threaded pins. These are available in different diameters and lengths (shaft, threaded part) and with different tips. Standard Schanz screws have trocar-shaped tips ( Fig 3.3.3-3a ). They always require predrilling.

Self-drilling and self-tapping Schanz screws have a sharp and specially designed tip that drills and cuts the thread in one pass: they are designed for use in metaphyseal bone ( Fig 3.3.3-3b ), Schanz screws are available in steel, titanium, or with a hydroxyapatite coating. The hydroxyapatite allows bone growth right up to the pin (osseo-integration) and reduces the incidence of pin loosening. These pins are used in cases where the external fixator is likely to be in place for a prolonged period.