High-energy injuries are often associated with other injuries, both in the foot and the rest of the body. The images show a severy injury of the foot with complete disorganization of the anatomy.
In the event of severe soft-tissue injury, possibly with vascular compromise, or co-morbidities (diabetes, etc.), external fixation may be the only treatment choice available, at least in the short term. Much later, reconstruction may be possible.
Plain x-rays will often show the injury pattern. CT with sagittal and coronal reconstruction is useful in obtaining a three-dimensional understanding of the injury. CT protocol should be thin cuts with large overlap.
Talonavicular joint function
The talonavicular (TN) joint allows for hindfoot motion in all planes. Loss of TN motion results in loss of complex hindfoot circumduction. It is therefore extremely important to retain TN function as it has a protective function for the adjacent joints. Loss of TN motion leads to adjacent joint degeneration (DJD). Retaining even a small amount of motion is thought to be protective for the adjacent joint function. The TN joint, because of its extensive range of motion, is also known as the “coxa pedis”.
The delicate leash of small vessels around the midfoot is often injured at the time of the original trauma. The vessels and soft tissue must be given time to recover. Soft-tissue defects also need to be addressed.
Maintain columnar length and relationship
Medial column length is crucial in maintaining the shape of the medial arch of the foot. If the navicular injury has resulted in comminution with loss of length, in reconstruction we must regain length, as well as normal geometry. Bridging the hardware distally and using bone graft will assure proper length of the medial column, overall shape and alignment of the foot. The form and function of the foot is dependent on the normal relationship between the medial and lateral columns. If the relative lengths of the medial and lateral columns are not maintained, foot deformity such as cavus or planus results. Relative shortening of the medial column leads to cavus whereas relative shortening of the lateral column leads to flat foot.
3. Soft-tissue considerations
External fixation as a temporizing measure
Blisters and soft-tissue injury are more common in higher-energy injuries and severe injuries to the underlying bone. Usually surgery is delayed to allow soft tissues to settle before definitive surgical care. Soft tissues must take priority over the bony injury and once the “wrinkle sign” is present, indicating soft-tissue relative recovery, the incidence of soft-tissue complication from bony surgery is decreased.
External fixation as definitive treatment
In higher-energy injuries and severe injuries to the soft tissue and underlying bone open reconstruction may not be possible. In such cases external fixation is used to stabilize the foot. This will maintain columnar bony alignment and allow soft-tissue reconstruction. Perhaps at a later date bony reconstruction may be possible. The goal of treatment in these injuries is often to maintain a foot that will fit into a shoe and allow ambulation. After severe injuries such as this, the foot may change size and shape. The overall alignment should, however, allow for function.
4. External fixation
Medial and lateral external fixation (with distractor device to restore columnar length) should be applied as soon after the injury as possible to stabilize the foot and decrease further injury to the soft tissues. The soft-tissue injuries can then be addressed. Antibacterial non-adherent dressings and vacuum assisted closure (VAC) can be used as needed.
Pearl If such a distractor device is not available a tube system with a distraction clamp can be used to achieve the same distraction.
Dressing Non-adherent antibacterial dressing is applied as a first layer in areas not covered by a VAC dressing. Hospital protocols are followed for pin care.
The patient should be counseled to keep the leg on a cushion and elevated. The level of elevation should be between the waist and the heart to decrease swelling. If the foot is elevated too high (above the heart), it may impede inflow. E.g. while seated on a couch, the foot should be on a cushion on the couch or small table.
Please note that in the very high-velocity injury we frequently have other components to consider. In this configuration of the external fixator we have combined external fixation of the foot with external fixation of the distal tibia and hindfoot and have added an anterior bar to prevent equinus deformity.