External Fixation

1. Due to logistical constraints and concern for infection, internal fixation is not recommended in most austere settings where evacuation to higher levels of care is possible. Surgeons should be well versed on external fixator placement for long bone and periarticular fractures.

In the setting of concomitant vascular injuries requiring repair or shunting, the orthopaedic surgeon and general surgeon should discuss the sequence of external fixation application (before or after the vascular procedure) considering the following:

- Ischemia time
- Degree of deformity in the fractured extremity, specifically the amount of shortening, angulation, mal-rotation, and instability across the fracture site
- Surgeon comfort level and experience affecting speed of external fixation application
- Indications to proceed directly to arterial repair versus need for initial shunting

Benefits of early vascular shunting or repair include reduced ischemia time and possibly reduced need for distal limb fasciotomies, while early fracture stabilization helps re-establish limb and vascular length across the site of injury as well as restore tissue planes for dissection and exposure. The treating surgeons should be mindful of the effects of restoring limb length and alignment on the vascular shunt/repair and plan their interventions to avoid disruption of restored blood flow while effectively stabilizing the limb.

2. External fixation affords adequate fracture stabilization to minimize additional soft tissue trauma and can provide easier access for wound care and re-evaluation for neurovascular injury and ACS. Early fracture stabilization may blunt inflammatory mediators associated with fractures in poly-trauma12,18 and can be rapidly applied in the multiple injured patient or in a mass casualty situation. Stability afforded by external fixation is also beneficial for pain control and ease of transport, and minimizes the need to manipulate the injured limb during transport and at each higher role of care.

3. External fixation in the austere environment is performed within the constraints of limited equipment and the lack of available fluoroscopy. Surgeons should be familiar with extremity bone and neurovascular anatomy in order to safely apply an external fixator for initial stabilization without the aid of fluoroscopy. Otherwise, splinting should be used for temporary stabilization. Specific portable external fixation kits designed for military use include self-drilling and self-tapping pins that use hand-powered drills for advancement into the bone. External fixation has been shown to be safe in the austere environment when performed at Role 2 and Role 3 facilities.20 However, caution is advised in attempting external fixation when no basic radiographic imaging is available to identify the fracture pattern, particularly for closed fractures where the facture pattern cannot be visualized or palpated through an open wound. In this case the limb should be splinted without traction and the patient moved to a level of care that has X-Ray capability.

4. External fixator stability is improved by increasing bony apposition at the fracture site, placing the connecting bars as close to the skin as is deemed safe, increasing the distance between pins in each fracture fragment, and using the largest diameter pin possible (typically, 5.0 mm pins in long bones). Two appropriately placed pins; above and below fracture fragment should provide sufficient stability and will allow receiving surgeons the most options for definitive fixation. Consider the skin incisions for future internal fixation plans when choosing pin sites.

5. The following guidelines allow the safe and effective placement of fixation pins in the austere environment, without the assistance of fluoroscopy but with some basic imaging of the fracture pattern available prior to pin placement.21 Pins should be placed both “near and far” from the fracture in both major bone fragments. The fracture ends in a closed fracture can be estimated by palpation/manipulation of the bone. One pin in each main fracture fragment should be placed typically 2-3 cm away from the fracture end to improve stability. Pins placed too near the fracture can decrease the external fixator’s ability to maintain stability if the pin only captures one bone cortex or is placed in fracture lines that are not grossly apparent. To place each pin, make a longitudinal incision approximately 1 cm in length at the planned pin site and bluntly dissect down to bone. The incision should be generous enough to accommodate the entire width of the pin, as trapped or tented skin contributes to skin irritation and pin tract infection, ultimately leading to pin loosening. Load the pin in either a powered drill or manual driver and place the pin into the incision until the pin meets bone. The pin tip can be used to palpate the edges or curve of the bone so that the central portion may be identified. After broaching the near cortex, hand advancement of the pin should be used to allow the surgeon to feel the far cortex, which is identified by encountering increased resistance while turning the pin. Engaging pin threads across the far cortex provides ideal stability. If intraoperative imaging is available, pins should be advanced until the drill tip is fully past the far cortex. If fluoroscopy is not available, manual advancement 6-8 full turns after reaching the inner surface the far cortex should provide sufficient engagement of the pin. Surgeons must always be aware of limb anatomy as excessive pin advancement can put neurovascular structures at risk.

6. The “far” pins should be placed as far from the fracture site as deemed safe. Intercalary fragments of segmental long bone fractures typically do not require pin fixation, and single pin fixation in these smaller fragments likely does not add to construct stability. Clamps designed to connect the pins and bars are available in the equipment sets, and the pin clamp may be used as a drill guide for appropriate placement of incisions between pin sites. However, using these clamps limits the potential distance between pins in a fracture segment and off-axis pins may not engage in the clamp sufficiently to the detriment of construct stability. External fixators may be placed to span joints if the fractures is near a joint or extends into the articular surface (knee, elbow). (Figures 1, 5, 6)

7. After placing pins, the pins in each fragment can be secured to each other with a pin clamp and tightened. Modified bars are then secured into each pin clamp, and long bars connect to the modified bars of each pin clamp/fracture fragment by using “bar-to-bar” connectors. One bar spanning each fracture fragment is often sufficient for fracture stability. If bar length is too short to span the fracture site, then 2 bars can be connected by a “bar-to-bar” clamp to gain the necessary length. The overall goal of any construct is to restore length and overall alignment of the limb by establishing a provisional reduction of the fracture (thus improving stability), reduce intracompartmental volume to allow tamponade of bleeding, and to restore vascular flow by “unkinking” vessels. Without fluoroscopy, simple longitudinal traction while grossly restoring coronal and sagittal alignment is sufficient for initial stabilization. When spanning the knee, the fixator should be tightened with slight knee flexion. (See Figure 1 below.)

8. Pins can be dressed with Xeroform or similar material and gauze, with Kerlex wrapping of the pins to provide stability to the skin. No formal pin care is recommended, especially in this acute phase, as formal cleaning protocols have failed to demonstrate improvement in pain, stability, or complications.22