Anterior Process Fracture of the Calcaneus
Edited by Samuel Dellenbaugh, MD
The anterior process of the calcaneus is a prominence on the heel bone (calcaneus) that is located in front and to the outside of the ankle (Figure 1). Fractures of the anterior process of the calcaneus occur following an acute injury to the foot. The way it occurs is often similar to that of an ankle sprain, where the foot is flexed in an inward and downward direction. The fracture occurs when the calcaneus and cuboid bones that make up the calcaneocuboid joint hit against each other, knocking off a rim of the top part of the calcaneus. In some instances, a ligament attached to the anterior process of the calcaneus is stretched with the foot in this position and pulls off a portion of the bone (avulsion fracture). Usually, the fracture often does not shift significantly. Patients typically report pain and swelling in front of and to the outside of the ankle. Although the injury is quite painful, patients may be able to walk with limp. These fractures are often misdiagnosed as ankle sprains, because the presentation is so similar.
Figure 1: Anterior Process of the Calcaneus
On examination, there will be tenderness and swelling over the injured area. The injured area is similar to that of an ankle sprain, although it is located closer to the toes than a standard ankle sprain (Figure 2). The skin and sensation is usually normal, although occasionally this injury can cause the nerve that runs on the outside of the foot (sural nerve) to be irritated, leading to burning or numbness over the outside of the foot.
Figure 2: Anterior Process Fracture of the Calcaneus: Location of Injury
A fracture of the anterior process of the calcaneus can usually be seen on a plain x-ray lateral view of the foot (Figure 3). This is a view taken from the side. However, this injury can often be quite subtle and can easily be missed. It can be confirmed by a CT or an MRI, which will show the small fracture fragment (Figure 4).
Figure 3: X-Ray Anterior Process Fracture of the Calcaneus
Figure 4: MRI Anterior Process Fracture of the Calcaneus
Most anterior process fractures of the calcaneus can be treated non-surgically. If the fracture fragment is not interfering with the function of the calcaneal cuboid joint, non-operative treatment is indicated. This consists of immobilization in a walker boot for typically six weeks, until the soft tissue injury and fracture have healed. In some incidences, the fracture will not completely heal, which is only problematic if it interferes with the joint function.
Surgical treatment of anterior calcaneal process fractures are reserved for fractures that interfere with the function of the calcaneal cuboid joint. For example, if the fracture is in such a position that the bone is irritating the calcaneocuboid joint, then surgical removal of this fragment is indicated.
In addition, patients that have persistent symptoms following an anterior process fracture of the calcaneus may benefit from surgical removal and cleaning out of the calcaneal cuboid joint. Recovery from surgery involves protecting the foot until the soft tissues have healed, and then gradually mobilizing the joint. This can take six weeks or more.
Complications that are specific to the removal of an anterior process of the calcaneus fracture include:
- Injury to the sural nerve – The sural nerve runs on the outside of the foot and can lead to numbness or a persistent burning sensation in this area.
- Arthritis of the calcaneal cuboid joint – Arthritis affecting the calcaneocuboid joint can occur, although this is unusual.
- Persistence of symptoms – The injured area may have ongoing pain.
Edited on May 30, 2020
Previously edited by Daniel Cuttica, DO and Stephen Pinney, MD