Calcaneal fractures are the most common tarsal fractures. They are caused by axial loading, most commonly from a fall or MVA. The fracture is created primarily by the driving force of the talus into the calcaneus; this crack can propagate into so called secondary fracture lines.
The calcaneus has two primary articulations (talus and cuboid) and multiple named processes. The posterior aspect of the calcaneus is called the tuberosity. Distally is an articulation with the cuboid. There is also a groove laterally under which the peroneus longus tendon passes. Superiorly there are 3 weight bearing facets, forming the articulation with the talus: the anterior, middle and posterior facets.
There are two important angles. The first is the Bohler angle. Bohler's angle is the compliment of the angle at the apex of the posterior facet. To construct Bohler's angle a line is drawn from the superior aspect of the anterior process to the superior aspect of the posterior facet. A second line is drawn from the superior aspect of the posterior facet to the superior most point of the calcaneal tuberosity. Bohler's angle is the angle formed between these two lines. A normal Bohler's angle is approximately 25 to 40 degrees. It should be obvious that this angle decreases as the height of the calcaneus is lost; as this angle shrinks as the height of the posterior facet decreases. The second angle is the angle of Gissane. This is drawn on a lateral radiograph representing the intersection of the downward slope of the posterior facet, with the upward slope going anterior. This is normally approximately 100 degrees. Medially is the sustentaculum tali. This is, one might say, a cantilevered ledge on which the medial talus rests. Ligamentous attachments to the calcaneus include the calcaneal fibular ligament laterally, an intraosseous talo calcaneal ligament, and the deltoid ligament medially.
Extra articular: (25-30%)
mostly avulsion type fractures: anterior process, sustentaculum tali, calcaneal tuberosity
Intra articular: (70-75%)
Rowe Classification: Types I-III do not involve the subtalar joint. Type I (20%) the fracture line may be through the tuberosity, the sustentaculum tali, or the anterior process of the calcaneus. Type II or beak fractures are uncommon. Type III (20%) are oblique fractures. Types IV and V(60%) involve the subtalar joint. Type V fractures are comminuted fractures with a centrally depressed fragment.
Essex-Lopresti classification: There are two fracture lines in this classification and based on the location of the secondary fracture line, there are two types of fracture:
• Tongue-type fx : The secondary fracture line extends directly posteriorly, producing a large superior, posterior, and lateral fragment, with the rest of the body forming the inferior fragment.
• Joint depression fx: The secondary fracture line begins at the crucial angle, extends posteriorly and exit the bone just posterior to the posterior articular facet.
Sanders classification: Based on coronal CT image at the level of posterior facet
• Type I: nondisplaced posterior facet
• Type II: one fx line in posterior facet (two fragments)
• Type III: two fx lines in posterior facet (three fragments)
• Type IV: three fx lines in posterior facet (four and more fragments)
Patients with calcaneal fractures have often sustained high energy injuries. Because of axial transmission of force, these patients must be examined for spinal and visceral injuries.
Radiographic studies should include an AP view, a lateral view (which would show Bohler's angle well), and a dedicated calcaneal view (also known as the Harris view). The Harris view is obtained with the ankle in dorsiflexion and a facet posteriorly along the course of the Achilles tendon. The x-ray beam is aimed from a position slightly distal to the foot, with an angle of incidence to the plantar surface of the foot of approximately 30 degrees. In general, however, precise definition of the calcaneus is best obtained via CT scanning.
Patients must be examined for concomitant injuries. Compresion fractures of the spine and fractures of the proximal femur are commonly caused by the same mechanism so beware!
It is helpful to image the contralateral foot even if you think it is not injured--as in many instances there is a bilateral injury. Besides, it can be helpful to image the contralateral (normal) foot to recognize idiosyncratic anatomical features of the given patient.
Extra-articular fractures can be treated non-operatively, unless the fragments are large, or, the case of the calcaneal tuberosity fracture, that the Achilles insertion disrupts the fracture further. In that case, a large screw fixation can be helpful.
Treatment of intra articular fractures runs a gamut from immobilization in situ to fully open approaches. The goals of treatment are anatomic restoration, if possible, or at least a recognition that a non-anatomic configuration is still compatible with function. Limited internal fixation and so called "semi open techniques" have been used. Typically an open approach into a lateral incision is used. It is essential that when approaching from the lateral side the fracture is properly excavated, and the fragments are restored to the anatomic position. Bone grafting is sometimes added. Most patients are not taken to the operating room acutely, and hence have some issues with soft tissue edema and skin blistering, which may influence the surgical technique. Surgery is thus timed, in many instances, to allow the soft tissue to be controlled, all the while not having the fracture fragments so sticky that they cannot be mobilized. The goals of surgery are to reduce the posterior facet and correct the loss of height. Additionally, attention must be paid to restoration of the articulations of the calcaneus.
Postoperative management includes immobilization and non-weight bearing.
Skin blistering and slough is possible. Some calcaneus fractures are associated with foot compartment syndromes and ultimate clawing of the toes. A complex regional pain syndrome also may ensue from a calcaneal fracture.
Complications from surgical treatment itself include problems with wound healing. In some patients the risk of infection is particularly high, even without a wound problem. There may be iatrogenic injury to the sural nerve or to the posterior neurovascular bundle, especially with a medial approach.
The calcaneus, of course, can heal in a non-united position with widening of the heel or loss of height. There may be entrapment of the peroneal tendons. Subtalar arthritis may form, along with the possibility of calcaneal cuboid arthritis as well. Non-unions are rare, but described.
Salvage of complications may involve subtalar or triple arthrodesis. Osteotomy or exostectomy may be needed.
Red Flags and Controversies
Which fracture needs to be fixed? Is this a case for referral to a traumatologist?