Calcaneal Avulsion Fracture -Calcaneal Tuber Fracture

Summary

Calcaneal avulsion fractures occur when the calf muscle contracts strongly causing the Achilles tendon to pull off (avulse) a section of the bone at the back of the heel. This injury is relatively uncommon compared to more typical calcaneal fractures. However, older individuals with weaker bone from osteoporosis are at higher risk for this injury. The injury usually occurs after a sudden movement with the calf muscle contracting strongly and the foot fixed on the ground or being forced upward. Patients will have pain and will usually not be able to bear any weight. If the fracture is significantly displaced it may be necessary to reposition the fracture on an urgent basis in order to avoid skin breakdown (necrosis) at the fracture site. Surgery to reposition displaced fractures back to their original position and stabilize it with screws is often required. Immobilization to allow the fracture to heal followed by therapy to regain strength and balance is need to ensure an optimal recovery.

Background

Calcaneal avulsion fractures are relatively uncommon fractures that occur when the strong Achilles tendon pulls a fragment of bone off the heel bone (calcaneus) at the point where the tendon attaches to the bone.  This fracture is also called a calcaneal tuber fracture, or a calcaneal tuberosity fracture. It is technically a calcaneus (heel bone) fracture, but it is much less common than a typical calcaneus fracture which often occurs following a loading injury to the heel such as falling from a height.  

There are a variety of activities that may cause an avulsion fracture of the calcaneal tuberosity including a sudden aggressive change of direction during a sporting activity. The actual mechanism causing this injury is a strong contraction of the calf muscle that applies considerable force to the Achilles tendon which in turn applies force and breaks the heel bone where the tendon attaches. Commonly the foot is fixed on the ground, or the ankle is being forced upwards while the Achilles tendon is applying force to the heel bone. Older individuals with weaker bone due to osteoporosis are more likely to suffer a calcaneal avulsion fracture.

Signs and Symptoms of a Calcaneal Avulsion Fracture

After this acute injury there will be considerable pain and swelling in the back of the heel where the Achilles tendon attaches to the heel bone. The injured individual usually will not be able to bear any weight due to the pain. There is often a notable deformity in this area with the skin being stretched (tented). This skin tenting can be problematic as breakdown of the skin from pressure necrosis may occur if it is left in this position for too long. 

Imaging Studies

X-rays will demonstrate the avulsion fracture. The view from the side of the ankle (lateral view) will identify the fracture. It will also demonstrate the extent of displacement of the calcaneal bone fragment that has been pulled off the main part of the heel bone.

If the extent of the fracture is unclear on plain x-ray, it may be necessary to obtain a CT scan. This gives a more detailed view of the heel bone and the extent of the fracture.

Treatment of Calcaneal Avulsion Fractures

There are two primary goals when treating a calcaneal avulsion fracture. The first is to take pressure off of the skin at the back of the heel. This is to avoid breakdown of the skin (necrosis) over the injured area. The second goal is to reposition the fracture so that it will heal optimally.

For some patients with a non-displaced or minimally displaced calcaneal avulsion fracture the skin will not be at risk -and the fracture will not need to be repositioned. This injury can be treated without surgery by protecting the fracture until the fracture has healed.

However, for most displaced calcaneal avulsion fractures surgery will be required. If the skin around the fracture fragment is under pressure this surgery should be performed expeditiously to remove the pressure from the skin and prevent any skin breakdown. If there is just swelling, but the skin around the fracture is fine, some delay prior to surgical fixation may be OK. The surgery itself involves repositioning the displaced fracture fragment of the heel bone (calcaneus) back where it originally was. This bone then needs to be stabilized with a few screws in order to keep it reduced in position until it heals adequately.

Typically, a period of relative immobilization in a cast for boot, combined with non-weightbearing or very limited weight-bearing through the heel is required for 6–8 weeks after the surgery in order to allow for adequate healing. At that time, a graduated increase in activity can be started. Therapy to work on range of motion, strengthening, gait retraining, and mobilizing the soft tissues around the injured area can be very helpful. It is often a number of months before the patients are walking reasonably normally, and a year or more before they have reached their point of maximum improvement.

Edited January 19, 2024