Practice Essentials
Fractures of the calcaneus (or os calcis) have been observed and documented for centuries. However, a true consensus regarding the management of these fractures has long eluded practitioners. [1]
Norris correctly described a compression mechanism in calcaneus fractures in 1839, and in 1843, Malgaigne described two types of calcaneal fractures; this description formed the first rudimentary classification system. With the advent of radiographic evaluation, several authors developed classification systems, including Bohler (in 1931), Essex-Lopresti (in 1951-2), Rowe et al (in 1963), and others. [2, 3] Essex-Lopresti first sought to distinguish intra-articular fractures of the calcaneus from extra-articular ones, correctly associating the intra-articular variety with a poorer long-term prognosis. [4]
The poor correlation of these comprehensive classification systems with functional outcomes hindered their widespread acceptance. [5, 6, 7] Only with the advent of computed tomography (CT) was the capability to evaluate accurately complex calcaneus injuries realized. Subsequently developed classification systems based on CT appearances, such as the one Sanders described, appear to provide more reliable indicators of prognosis and are better able to select injuries that are particularly amenable to surgical intervention. [8, 9, 10]
Despite improvements in imaging, as well as a better understanding of the patterns of injury in complex fractures of the calcaneus, opinions on the management of such injuries continue to differ. [11, 12] Prospective studies have attempted to show benefit either with early operative intervention or with nonoperative measures. [13, 14, 15] Each modality has at times enjoyed more attention and enthusiasm in the literature. A frustrating factor that perpetuates this disagreement is the subset of calcaneus fractures with poor long-term outcomes, regardless of management. Cotton commented in 1916 that "the man who breaks his heel bone is done so far as his industrial future is concerned." [16]
Extra-articular fractures, with some exceptions, are generally treated in a closed manner. Intra-articular fractures may be treated in a closed fashion but are more commonly treated with a combination of open reduction, ostectomy, osteotomy, internal fixation, and/or arthrodesis of the subtalar and calcaneocuboid joints. Nondisplaced intra-articular fractures are generally treated in a closed fashion. Severely comminuted intra-articular fractures may be treated with a combination of open reduction and internal fixation (ORIF) and arthrodesis of the subtalar joint.
Anatomy
The calcaneus (os calcis) is the largest of the tarsal bones. The calcaneus has four articular facets, which allow it to articulate with the talus superiorly and the cuboid anteriorly. The three subtalar facets (anterior, middle, and posterior) must function as a unit, and any fracture that interrupts their alignment is, by definition, an intra-articular fracture. The posterior facet is a major weightbearing surface, though the anterior and middle facets bear more weight per unit area.
The calcaneal composition has a significant influence on preoperative planning. The body of the calcaneus is composed primarily of cancellous bone, having a comparatively thin cortex. There are, however, several important areas of increased bony density that are particularly amenable to screw placement, including the following:
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Angle of Gissane
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Plantar posterior tubercle
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Anterior aspect of the anterior process
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Sustentaculum tali
The tibial artery, nerve, posterior tibial tendon, and flexor hallucis longus tendon course along the medial wall of the calcaneus, though they are rarely damaged in calcaneus fractures caused by blunt force. These structures are thought to be shielded by the medial projection of the sustentaculum tali, which is held in place by the medial talocalcaneal interosseous ligaments during fracture of the calcaneus. Laterally, the peroneal tubercle provides a groove for the peroneal tendons (the brevis superiorly and the longus inferiorly). (See Ankle Joint Anatomy.)
Pathophysiology
The mechanism of injury in calcaneus fractures typically involves a high-energy axial load applied to the heel, which drives the talus downward onto the calcaneus. The resultant primary fracture line extends from the lateral aspect of the angle of Gissane in a posteromedial direction, initiating an oblique, primary fracture line. It is from this point that multiple secondary fracture lines may develop. The subtalar joint is involved 75% of the time.
Essex-Lopresti described the following two calcaneus fracture subtypes [4] :
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Joint-depression fractures
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Tongue-type fractures
Both of these describe the primary fracture line. In the tongue-type fracture, the secondary fracture line directly extends in a posterior direction, producing a large superior, posterior, and lateral fragment, with the remainder of the calcaneal body forming the inferior fragment. In the more frequent joint-depression fracture, the secondary fracture line begins at the angle of Gissane and extends posteriorly but deviates dorsally to exit the bone just posterior to the posterior articular facet. This fracture fragment contains most of the posterior facet.
Etiology
Nearly all intra-articular fractures of the calcaneus are caused by an axial loading mechanism, which is directed through the laterally situated (in relation to the weightbearing axis of the lower extremity) plantar tuberosity of the calcaneus. Causes of fractures include the following:
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Fall from height (usually ≥6 ft [~1.8 m])
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Motor vehicle collisions
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Impact on a hard surface while running or jumping
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Extra-articular fracture of the calcaneal body and plantar tuberosity caused by blunt-force injury
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Avulsion injuries with abrupt contraction of the Achilles tendon
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Overuse injury, or stress fracture, in athletes
Extra-articular injuries are more likely to occur with a sudden twisting force applied to the hindfoot than with other mechanisms.
Epidemiology
Calcaneus injuries represent 2% of all fractures seen in adults. The os calcis is the most frequently fractured tarsal bone, accounting for more than 60% of tarsal fractures. Calcaneus fractures are most commonly seen in young men.
Extra-articular fractures account for 30% of all calcaneus fractures in adults. The most common extra-articular fracture is a calcaneal body fracture. Fractures of the anterior process represent 10-15% of extra-articular injuries; these are the only type of calcaneus fractures that are more common in women than in men. Fractures of the superior tuberosity beak or avulsion fractures represent 10% of extra-articular injuries. Sustentaculum tali fractures are rarely seen as isolated injuries.
Intra-articular fractures constitute 70% of all calcaneus fractures in adults.
Calcaneus fractures are rarely encountered as open fractures. Open injuries that have been reported have occurred in only 2% of cases.
Prognosis
As has long been known, intra-articular fractures of the calcaneus result in morbidity figures substantially higher than those of extra-articular fractures.
Zhang et al prospectively compared a minimally invasive lateral approach with a conventional sinus tarsi approach for displaced intra-articular (Sanders type II, III, and IV) fractures of the calcaneus. [17] Whereas the minimally invasive approach resulted in a lower postoperative complication rate for Sanders type II and III injuries, functional outcomes were similar. The sinus tarsi approach yielded statistically significant improvements in functional outcomes over the minimally invasive approach, but this was limited to patients with Sanders type IV injuries.
Schuberth et al performed a retrospective study of 24 cases of minimally invasive ORIF of intra-articular calcaneal fractures. [18] Postoperatively, there were significant changes in articular stepoff of the posterior facet, medial-wall displacement, and the Böhler angle. No soft-tissue complications occurred, and none of the 18 patients followed for more than 1 year progressed to subtalar fusion. The authors concluded that a minimally invasive approach can improve radiographic parameters consistent with the goals of restoration of articular congruity, calcaneal morphology, and calcaneal height and can achieve satisfactory results with minimal risk of wound complication.
Grala et al reported on two groups of patients (N = 42) who underwent operative treatment for articular fractures of the calcaneus, one (n = 23) treated by standard reconstruction and the other (n = 19) treated with a large bone distractor. [19] Patients in whom the distractor was used had shorter operating times, and less effort was required in performing the surgery. The bone distractor apaprently retracted the soft-tissue flap, helped reduce the articular and tuberosity fragment, and improved visualization by distracting the posterior talocalcaneal joint. All fractures healed well or very well.
Dhillon et al performed a prospective evaluation (N = 16) comparing results in patients who had open fractures treated with minimally invasive surgery (MIS; group 1; n = 16) and patients who had closed fractures treated with ORIF (group 2; n = 9). [20] At 1 year, group 1 had a mean Maryland Foot Score (MFS) of 79 and an American Orthopaedic Foot and Ankle Society (AOFAS) score of 77.37, whereas group 2 had an MFS of 84.4 and and AOFAS score of 86.1. The authors concluded that MIS can achieve acceptable fracture reduction and that it can serve as the primary definitive treatment option for open fractures of the calcaneus.
Eckstein et al reported long-term (≥20-y) follow-up of 22 patients who underwent surgical treatment of displaced calcaneal fractures. [21] Assessment involved a combination of radiography with Short Form (SF)-36 and AOFAS questionnaires. At follow-up, only 12 of the 22 patients (55%) of the patients had very good or good clinical results; four had average results, and six had poor results. The results of this study did not lend support to the view that ORIF yields better outcomes than conservative therapy for these fractures.
Chen et al investigated a combination of minimally invasive dual incision and internal fixation with mini plates as an alternative to ORIF in 20 patients with Sanders type III intra-articular calcaneal fractures and a posterior subtalar articular displacement greater than 2 mm. [22] The Böhler angle, the Gissane angle, and the height and length of the calcaneus were increased after treatment. Outcomes according to the AOFAS score were excellent or good in 80% of cases. Mean postoperative pain score on the Visual Analogue Scale (VAS) was 1.6. Complications (eg, malunion or screw positioning deviation) occurred in six patients and delayed wound healing in one. There were no wound infections.
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Calcaneus fractures. Comminuted fracture of calcaneus sustained in motorcycle accident. Note loss of Böhler angle.
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Calcaneus fractures. Axial radiograph reveals comminuted fracture of calcaneal body.
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Calcaneus fractures. Avulsion-type fracture of calcaneus, sustained when patient fell 6 ft from ladder onto solid ground. Because of distraction of fracture fragments, injury was treated with open reduction and internal fixation.
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Calcaneus fractures. Status post open reduction and internal fixation.
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Calcaneus fractures. Bilateral calcaneus fractures sustained in motor vehicle collision. Compare minimally displaced calcaneal tuberosity fracture on patient's left side with comminuted intra-articular (Sanders type III) fracture on right.
